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Sample records for crystal nickel superalloys

  1. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  2. Anisotropy of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.; Dreshfield, R. L.

    1980-01-01

    The effects of crystal orientation on the mechanical properties of single crystals of the nickel-based superalloy Mar-M247 are investigated. Tensile tests at temperatures from 23 to 1093 C and stress rupture tests at temperatures from 760 to 1038 C were performed for 52 single crystals at various orientations. During tensile testing between 23 and 760 C, single crystals with high Schmid factors were found to be favorably oriented for slip and to exhibit lower strength and higher ductility than those with low Schmid factors. Crystals which required large rotations to become oriented for cross slip were observed to have the shortest stress rupture lives at 760 C, while those which required little or no rotation had the longest lives. In addition, stereographic triangles obtained for Mar-M247 and Mar-M200 single crystals reveal that crystals with orientations near the -111 had the highest lives, those near the 001 had high lives, and those near the 011 had low lives.

  3. Compositional Effects on Nickel-Base Superalloy Single Crystal Microstructures

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Garg,Anita; Rogers, Richard B.; Nathal, Michael V.

    2012-01-01

    Fourteen nickel-base superalloy single crystals containing 0 to 5 wt% chromium (Cr), 0 to 11 wt% cobalt (Co), 6 to 12 wt% molybdenum (Mo), 0 to 4 wt% rhenium (Re), and fixed amounts of aluminum (Al) and tantalum (Ta) were examined to determine the effect of bulk composition on basic microstructural parameters, including gamma' solvus, gamma' volume fraction, volume fraction of topologically close-packed (TCP) phases, phase chemistries, and gamma - gamma'. lattice mismatch. Regression models were developed to describe the influence of bulk alloy composition on the microstructural parameters and were compared to predictions by a commercially available software tool that used computational thermodynamics. Co produced the largest change in gamma' solvus over the wide compositional range used in this study, and Mo produced the largest effect on the gamma lattice parameter and the gamma - gamma' lattice mismatch over its compositional range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had a significant impact on their concentrations in the gamma matrix and, to a smaller extent, in the gamma' phase. The gamma phase chemistries exhibited strong temperature dependencies that were influenced by the gamma and gamma' volume fractions. A computational thermodynamic modeling tool significantly underpredicted gamma' solvus temperatures and grossly overpredicted the amount of TCP phase at 982 C. Furthermore, the predictions by the software tool for the gamma - gamma' lattice mismatch were typically of the wrong sign and magnitude, but predictions could be improved if TCP formation was suspended within the software program. However, the statistical regression models provided excellent estimations of the microstructural parameters based on bulk alloy composition, thereby demonstrating their usefulness.

  4. SOLIDIFICATION OF NICKEL-BASED SINGLE CRYSTAL SUPERALLOY BY ELECTRIC FIELD

    Institute of Scientific and Technical Information of China (English)

    Y.S. Yang; X.H. Feng; G.F. Cheng; Y.J. Li; Z.Q. Hu

    2005-01-01

    The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al,Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ'phase is smaller with the electric field than that without the electric field.

  5. Recrystallization of Single Crystal Nickel-Based Superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing; TAO Chun-hu; LU Xin; LIU Chang-kui; HU Chun-yan; BAI Ming-yuan

    2009-01-01

    A series of experiments of investigating the recrystallization of single crystal DD3 superalloy were carried out. The threshold temperature for recrystallization and the effect of annealing temperature on recrystaUization were studied. The results show that the threshold temperature for recrystallization of the shot-peened DD3 samples is be-tween 1 000 ℃ and 1 050℃ under the condition of annealing for 2 h, and the recrystallization depth increases with the rise of the annealing temperature. Below 1 150 ℃, the recrystallization depth increases slowly with the tempera-ture climbing, while above 1 150 ℃, the recrystallization depth increases quickly with the rise of the temperature. The solution of the γ' phase is a critical factor of the recrystallization behavior of DD3 superalloy. In addition, the ki-netics and microstructural evolution of recrystallization at 1 200 ℃ were also studied. It is found that the recrystalli-zation progresses rapidly at 1 200℃ through the growth of fully developed recrystallized grains, and the recrystalli-zation process on the shot-peened surface is similar to that of wrought materials, including nucleation of reerystalliza-tion, growth of new grains into the matrix, and growth of new grains by swallowing up each other.

  6. Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Ming; Zhuo, Longchao [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China); Liu, Zhanli [Applied Mechanics Lab, School of Aerospace, Tsinghua University, Beijing 100084 (China); Lu, Xiaogang [School of Materials Science and Engineering, Shanghai University, Shanghai (China); Shi, Zhenxue; Li, Jiarong [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhu, Jing, E-mail: jzhu@mail.tsinghua.edu.cn [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, The State Key Laboratory of New Ceramics and Fine Processing, Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084 (China)

    2015-07-29

    The mechanical properties of nickel-based single crystal superalloys deteriorate with increasing misorientation, thus the finished product rate of the casting of single crystal turbine airfoils may be reduced due to the formation of grain boundaries especially when the misorientation angle exceeds to some extent. To this day, evolution of the microstructures at the grain boundaries with misorientation and the relationship between the microstructures and the mechanical properties are still unclear. In this work a detailed characterization of the misorientation related microstructure at the grain boundary in DD6 single crystal superalloy has been carried out using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques; the elemental distribution at the grain boundaries has been analyzed by energy dispersive (EDS) X-ray mapping; and the effect of precipitation of μ phases at the grain boundary on the mechanical property has been evaluated by finite element calculation. It is shown that the proportion of γ phase at the grain boundaries decreases, while the proportion of γ′ phase at the grain boundaries increases with increasing misorientation; the μ phase is precipitated at the grain boundaries when the misorientation angle exceeds about 10° and thus it could lead to a dramatic deterioration of the mechanical properties, as well as that the enrichment of Re and W gradually disappears as the misorientation angle increases. All these factors may result in the degradation of the mechanical properties at the grain boundaries as the misorientation increases. Furthermore, the finite element calculation confirms that precipitation of μ phases at the grain boundary is responsible for the significant deterioration of the mechanical properties when the misorientation exceeds about 10°. This work provides a physical imaging of the microstructure for understanding the relationship between the mechanical properties and the misorientation

  7. Microstructure-property relationships in directionally solidified single-crystal nickel-base superalloys

    Science.gov (United States)

    Mackay, Rebecca A.; Nathal, Michael V.

    1988-01-01

    This paper discusses some of the microstructural features which influence the creep properties of directionally solidified and single-crystal nickel-base superalloys. Gamma prime precipitate size and morphology, gamma-gamma (prime) lattice mismatch, phase instability, alloy composition, and processing variations are among the factors considered. Recent experimental results are reviewed and related to the operative deformation mechanisms and to the corresponding mechanical properties. Special emphasis is placed on the creep behavior of single-crystal superalloys at high temperatures, where directional gamma (prime) coarsening is prominent, and at lower temperatures, where gamma (prime) coarsening rates are significantly reduced. It can be seen that very subtle changes in microstructural features can have profound effects on the subsequent properties of these materials.

  8. Rafting in single crystal nickel-base superalloys — An overview

    Indian Academy of Sciences (India)

    M Kamaraj

    2003-02-01

    Currently nickel-base single crystal (SX) superalloys are considered for the manufacture of critical components such as turbine blades, vanes etc., for aircraft engines as well as land-based power generation applications. Microstructure and high temperature mechanical properties are the major factors controlling the performance of SX superalloys. Rafting is an important phenomenon in these alloys which occurs during high temperature creep. It is essential to understand the rafting mechanism, and its characteristics on high temperature properties before considering the advanced applications. In this review article, the thermodynamic driving force for rafting with and without stress is explained. The nature and influence of rafting on creep properties including pre-rafted conditions are discussed. In addition, the effect of stress state on $\\gamma /\\gamma'$ rafting, kinetics and morphological evolution are discussed with the recent experimental results.

  9. Prediction of recrystallisation in single crystal nickel-based superalloys during investment casting

    Directory of Open Access Journals (Sweden)

    Panwisawas Chinnapat

    2014-01-01

    Full Text Available Production of gas turbines for jet propulsion and power generation requires the manufacture of turbine blades from single crystal nickel-based superalloys, most typically using investment casting. During the necessary subsequent solution heat treatment, the formation of recrystallised grains can occur. The introduction of grain boundaries into a single crystal component is potentially detrimental to performance, and therefore manufacturing processes and/or component geometries should be designed to prevent their occurrence. If the boundaries have very low strength, they can degrade the creep and fatigue properties. The root cause for recrystallisation is microscale plasticity caused by differential thermal contraction of metal, mould and core; when the plastic deformation is sufficiently large, recrystallisation takes place. In this work, numerical and thermo-mechanical modelling is carried out, with the aim of establishing computational methods by which recrystallisation during the heat treatment of single crystal nickel-based superalloys can be predicted and prevented prior to their occurrence. Elasto-plastic law is used to predict the plastic strain necessary for recrystallisation. The modelling result shows that recrystallisation is most likely to occur following 1.5–2.5% plastic strain applied at temperatures between 1000 ∘C and 1300 ∘C; this is validated with tensile tests at these elevated temperatures. This emphasises that high temperature deformation is more damaging than low temperature deformation.

  10. Mapping single-crystal dendritic microstructure and defects in nickel-base superalloys with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Husseini, Naji S. [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States)], E-mail: najihuss@umich.edu; Kumah, Divine P. [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States); Yi, Jian Z.; Torbet, Christopher J. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Arms, Dohn A.; Dufresne, Eric M. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Pollock, Tresa M.; Wayne Jones, J. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Clarke, Roy [Applied Physics Program, University of Michigan, Ann Arbor, MI 48109 (United States)

    2008-10-15

    Solidification of single-crystal nickel-base superalloys introduces large-scale segregation of constituent elements and defects such as dislocations and mosaicity. By exploiting the energy tunability and interference capabilities of high-brilliance X-ray radiation, key structural features of the dendritic single crystals were mapped over large areas. Interference and diffraction of synchrotron X-rays revealed significant misorientations between individual dendrites in the as-solidified state. For the first time this mosaic structure was quantified for an array of dendrites and correlated with the density of 'grown-in' dislocations whose density ranged from 10{sup 7} to 10{sup 8} cm{sup -2}. Absorption contrast permitted simultaneous mapping of the distribution of refractory metal additives (e.g. rhenium and tungsten), which segregated preferentially to the dendrite cores with a linear composition gradient toward the interdendritic regions. The results demonstrate that synchrotron X-ray imaging is promising for in situ studies of single-crystal structure and defects in nickel-base superalloys.

  11. Changes in the microstructure occurring during the creep of single crystal nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, P.; Komenda, J. [Institutet foer Metallforskning, Stockholm (Sweden)

    1996-12-01

    Nickel-base superalloy single crystal components are now being introduced into industrial gas turbines as first row turbine blades report and in the future methods of remaining life assessment will be required. In this report an introduction to single crystal alloys is given and the effects of service exposure and principles of remaining life assessment of nickel-base superalloys have been reviewed. During creep (in cast Ni-base superalloys) cavities appear at grain boundaries and shape changes occur in the {gamma}` particles. Interrupted and full length creep tests have been performed at 750 and 950 deg C on the Ni-base single crystal alloy CMSX-4 and the resulting changes in microstructure have been quantified using a wide variety of parameters. The solidification process results in interdendritic porosity and the {gamma}` particles are initially cuboidal in shape. At 750 deg C no changes in the particles or porosity could be detected. At 950 deg C the volume fraction and number per sq.mm of measured cavities increased during creep. The smallest cavities measured by optical microscopy were 2-3 {mu}m in diameter, which was the limit of resolution of the system. The increase in cavity numbers is caused by the growth of cavities originally under 2 {mu}m. At 950 deg C the {gamma}` particles coalesced during creep to form a network of rafts, containing isolated plates of matrix and the volume percent of {gamma}` increased from ca 50 to ca 75%. The rafts reached their maximum length before 2% strain, but continued to thicken throughout the test. Although of different dimensions, the aspect ratio (length-to-width ratio as measured by the intersection of chords) of the {gamma}` rafts and the matrix plates were similar at the same levels of strain, reaching a maximum before 2% strain. These changes at 950 deg C were strain- and not time-dependent. Based on these findings, a way forward for the remaining life assessment of single crystal components has been proposed.

  12. Microstructure Evolution of a Single Crystal Nickel-Base Superalloy During Heat Treatment and Creep

    Institute of Scientific and Technical Information of China (English)

    YANG Da-yun,JIN Tao; ZHAO Nai-ren; WANG ZHi-hui; SUN Xiao-feng; GUAN Heng-rong; HU Zhuang-qi

    2004-01-01

    Microstructure evolution of a single crystal nickel-base superalloy during heat treatment and tensile creep at1010℃ and 248 MPa for 30h was observed and analyzed. Internal stresses because of lattice mismatch between γ and γphase provided the driving force for γ shape evolution during heat treatment. More than 65 vol. % distorted cubic γ phase keeping coherency with the γ matrix precipitated after solution at 1295 ℃ for 32h. The shape of γ phase was perfectly cubic with increasing precipitate size during the two-step aging treatment. Due to the applied stress and internal stress field the continuous γ-γ lamellar structure perpendicular to the applied stress was formed after 30h tensile creep.

  13. On Post-Weld Heat Treatment of a Single Crystal Nickel-Based Superalloy Joint by Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    T. J. Ma

    2015-09-01

    Full Text Available Three types of post-weld heat treatment (PWHT, i.e. solution treatment + primary aging + secondary aging (I, secondary aging (II, and primary aging + secondary aging (III, were applied to a single crystal nickel-based superalloy joint made with linear friction welding (LFW. The results show that the grains in the thermomechanically affected zone (TMAZ coarsen seriously and the primary γ' phase in the TMAZ precipitates unevenly after PWHT I. The primary γ' phase in the TMAZ and weld zone (WZ precipitates insufficiently and fine granular secondary γ' phase is observed in the matrix after PWHT II. After PWHT III, the primary γ' phase precipitates more sufficiently and evenly compared to PWHTs I and II. Moreover, the grains in the TMAZ have not coarsened seriously and fine granular secondary γ' phase is not found after PWHT III. PWHT III seems more suitable to the LFWed single crystal nickel-based superalloy joints when performing PWHT.

  14. Influence of composition on microstructural parameters of single crystal nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    MacKay, R.A., E-mail: Rebecca.A.MacKay@nasa.gov [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Gabb, T.P. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); Garg, A. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States); University of Toledo, 2801 W. Bancroft, Toledo, Ohio 43606 (United States); Rogers, R.B.; Nathal, M.V. [NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, Ohio 44135 (United States)

    2012-08-15

    Fourteen nickel-base superalloy single crystals containing a range of chromium (Cr), cobalt (Co), molybdenum (Mo), and rhenium (Re) levels, and fixed amounts of aluminum (Al) and tantalum (Ta), were examined to determine the effect of bulk composition on basic microstructural parameters, including {gamma} Prime solvus, {gamma} Prime volume fraction, topologically close-packed (TCP) phases, {gamma} and {gamma} Prime phase chemistries, and {gamma}-{gamma} Prime lattice mismatch. Regression models describing the influence of bulk alloy composition on each of the microstructural parameters were developed and compared to predictions by a commercially-available software tool that used computational thermodynamics. Co produced the largest change in {gamma} Prime solvus over the wide compositional range explored and Mo produced the biggest effect on the {gamma} lattice parameter over its range, although Re had a very potent influence on all microstructural parameters investigated. Changing the Cr, Co, Mo, and Re contents in the bulk alloy had an impact on their concentrations in the {gamma} matrix and to a smaller extent in the {gamma} Prime phase. The software tool under-predicted {gamma} Prime solvus temperatures and {gamma} Prime volume fractions, and over-predicted TCP phase volume fractions at 982 Degree-Sign C. However, the statistical regression models provided excellent estimations of the microstructural parameters and demonstrated the usefulness of such formulas. - Highlights: Black-Right-Pointing-Pointer Effects of Cr, Co, Mo, and Re on microstructure in new low density superalloys Black-Right-Pointing-Pointer Co produced a large change in {gamma} Prime solvus; Mo had a large effect on lattice mismatch. Black-Right-Pointing-Pointer Re exhibited very potent influence on all microstructural parameters was investigated. Black-Right-Pointing-Pointer {gamma} and {gamma} Prime phase chemistries both varied with temperature and alloy composition. Black

  15. DENDRITE REFINING AND EUTECTIC TRANSFORMATION BEHAVIOR OF NICKEL-BASE SINGLE CRYSTAL (NBSC) SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Because of the low temperature gradient and growth rate, the microstructure of the conventional single crystal superalloy made by HRS processing is coarse dendrite with well developed sidebranches and has serious segregation. With the help of the high temperature gradient directional solidification equipment (HGDS), the solidification cooling rate is greatly increased. Study on microstructure of the Ni-base single crystal superalloy solidified at much higher cooling rate shows that the dendrite arm spacing is highly refined, of which the primary dendrite arm spacing can be made to be 38μm, just as 1/10 as that by conventional HRS processing. With the increase of the cooling rate, the amount of the eutectic increases and then decreases. In the superfine columnar dendrite, the amount of γ/γ′eutectic is much fewer and its size is very small. This is useful to homogenize the microsegregation and improve the property of the material.

  16. Influences of processing parameters on microstructure during investment casting of nickel-base single crystal superalloy DD3

    Directory of Open Access Journals (Sweden)

    Gao Sifeng

    2012-05-01

    Full Text Available The effects of solidification variables on the as-cast microstructures of nickel-base single crystal superalloy DD3 have been investigated by using the modified Bridgman apparatus. The experiments were performed under a thermal gradient of approximately 45 K·cm-1 and at withdrawal rates ranging from 30 to 200 m·s-1. The experimental results show that the primary and secondary dendritic arm spacings (PDAS and SDAS decrease when the withdrawal rate is increased. Compared with the theoretical models of PDAS, the results are in good agreement with Trivedi’s model. The relationships of PDAS and SDAS with withdrawal rates can be described as l1 = 649.7V -0.24±0.02 and l2 = 281V -0.32±0.03, respectively. In addition, the size of the γ′ phase significantly decreases with increasing withdrawal rate.

  17. Effects of Microstructural Parameters on Creep of Nickel-Base Superalloy Single Crystals

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Nathal, Michael V.

    2013-01-01

    Microstructure-sensitive creep models have been developed for Ni-base superalloy single crystals. Creep rupture testing was conducted on fourteen single crystal alloys at two applied stress levels at each of two temperatures, 982 and 1093 C. The variation in creep lives among the different alloys could be explained with regression models containing relatively few microstructural parameters. At 982 C, gamma-gamma prime lattice mismatch, gamma prime volume fraction, and initial gamma prime size were statistically significant in explaining the creep rupture lives. At 1093 C, only lattice mismatch and gamma prime volume fraction were significant. These models could explain from 84 to 94 percent of the variation in creep lives, depending on test condition. Longer creep lives were associated with alloys having more negative lattice mismatch, lower gamma prime volume fractions, and finer gamma prime sizes. The gamma-gamma prime lattice mismatch exhibited the strongest influence of all the microstructural parameters at both temperatures. Although a majority of the alloys in this study were stable with respect to topologically close packed (TCP) phases, it appeared that up to approximately 2 vol% TCP phase did not affect the 1093 C creep lives under applied stresses that produced lives of approximately 200 to 300 h. In contrast, TCP phase contents of approximately 2 vol% were detrimental at lower applied stresses where creep lives were longer. A regression model was also developed for the as-heat treated initial gamma prime size; this model showed that gamma prime solvus temperature, gamma-gamma prime lattice mismatch, and bulk Re content were all statistically significant.

  18. The influence of cobalt, tantalum, and tungsten on the elevated temperature mechanical properties of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-10-01

    The influence of composition on the tensile and creep strength of [001] oriented nickel-base superalloy single crystals at temperatures near 1000 °C was investigated. Cobalt, tantalum, and tungsten concentrations were varied according to a matrix of compositions based on the single crystal version of MAR-M247.* For alloys with the baseline refractory metal level of 3 wt pct Ta and 10 wt pct W, decreases in Co level from 10 to 0 wt pct resulted in increased tensile and creep strength. Substitution of 2 wt pct W for 3 wt pct Ta resulted in decreased creep life at high stresses, but improved life at low stresses. Substitution of Ni for Ta caused large reductions in tensile strength and creep resistance, and corresponding increases in ductility. For these alloys with low Ta plus W totals, strength was independent of Co level. The effects of composition on properties were related to the microstructural features of the alloys. In general, high creep strength was associated with high levels of γ' volume fraction, γ-γ' lattice mismatch, and solid solution hardening.

  19. Interfacial Dislocation Networks and Creep in Directional Coarsened Ru-Containing Nickel-Base Single-Crystal Superalloys

    Science.gov (United States)

    Carroll, L. J.; Feng, Q.; Pollock, T. M.

    2008-06-01

    Mechanisms of creep deformation in nickel-base superalloy single crystals in the directional coarsening regime have been studied in alloys with large variations in γ- γ' lattice misfit and phase composition, achieved by Ru additions and variable levels of Cr and Co. Interfacial dislocation spacings established by long-term annealing experiments under no externally applied stress indicate that the experimental alloys have high-temperature lattice misfits ranging from near-zero to as large as -0.65 pct. Variation in misfit influences the stress-induced directional coarsening (rafting) behavior during creep deformation at 950 °C and 290 MPa. In postcreep deformed material, the density of excess dislocations (defined as the dislocations beyond those necessary to relieve the lattice misfit) at the γ- γ' interfaces varied with alloy composition, with the most creep-resistant alloy containing the highest excess interfacial dislocation density. In the directional coarsening creep regime, continued deformation requires shearing of the γ' rafts and is strongly influenced by the resistance of the precipitates to shearing as well as the interfacial dislocation structure. A preliminary model for creep in the rafting regime is developed.

  20. The influence of cobalt, tantalum, and tungsten on the microstructure of single crystal nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1985-10-01

    The influence of composition on the microstructure of single crystal nickel-base superalloys was investigated. Co was replaced by Ni, and Ta was replaced by either Ni or W, according to a matrix of compositions based on MAR-M247. Substitution of Ni for Co caused an increase in γ' solvus temperature, an increase in γ-γ' lattice mismatch, and the precipitation of W-rich phases in the alloys with high refractory metal levels. Substitution of Ni for Ta caused large decreases in γ' solvus temperature, γ' volume fraction, and γ-γ' lattice mismatch, whereas substitution of W for Ta resulted in smaller decreases in these features. For the alloys with γ' particles that remained coherent, substitution of Ni for Co caused an increase in γ' coarsening rate. The two alloys with the largest magnitude of lattice mismatch possessed γ' particles which lost coherency during unstressed aging and exhibited anomalously low coarsening rates. Creep exposure at 1000 °C resulted in the formation of γ' lamellae oriented perpendicular to the applied stress axis in all alloys.

  1. Creep properties of the single crystal nickel-base superalloy CMSX-4

    Energy Technology Data Exchange (ETDEWEB)

    Linde, L.; Henderson, P

    1998-10-01

    Creep testing has been performed on the nickel based single crystal alloy CMSX-4 at 750, 982 and 1050 deg C. The crystals had been hot isostatically pressed before testing. At 750 deg C the material exhibited primary creep which was not present at the higher temperatures. A tensile pre-creep at 750 deg C and 250 MPa for 4400 hours reduced the amount of primary creep and the minimum creep rate during creep at 750 deg C and 600 MPa. The pre-crept specimen also failed prematurely at an extensometer ridge. At 982 deg C and 206.9 MPa, tests were interrupted at 0.98, 1.96 and 7.5% strain for investigation of the microstructural changes during a test. Quantitative metallography of specimens after testing showed that at 750 deg C the {gamma}/{gamma}` microstructure was practically unchanged with cuboidal {gamma}` particles in a {gamma} matrix. At the higher temperatures, a transformation of the structure occurred where rafts of {gamma}` phase were formed and the rafts became shorter and thicker as the creep strain increased. Porosity measurements of tested material showed a large increase in porosity up to 2% strain, thereafter the increase was less. One specimen failed in an unexpected manner and was studied using electron back scatter patterns (EBSP). The EBSP investigation revealed the presence of an isolated grain in the gauge length where the fracture occurred 7 refs, 26 figs, 3 tabs

  2. Influence of precipitate morphology on intermediate temperature creep properties of a nickel-base superalloy single crystal

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.; Miner, R. V.

    1989-01-01

    The relative creep behavior of cuboidal (as-heat treated) and rafted (precrept at 1000 C) gamma-prime microstructures in the single-crystal Ni-based superalloy NASAIR 100 at 760 C was investigated using SEM and TEM examinations of materials at various stages of creep. It was found that, at high applied stresses, the crystals with cuboidal gamma-prime structure had both lower minimum creep rates and longer rupture lives than the crystals with lamellar gamma-prime. At lower stress levels, the initially cuboidal gamma-prime microstructure maintained a lower creep rate, but exhibited a similar rupture life compared to the prerafted crystals.

  3. Measurements of γ/γ' Lattice Misfit and γ' Volume Fraction for a Ru-containing Nickel-based Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    X.P. Tan; J.L. Liu; X P Song; T. Jin; X.F. Sun; Z.Q. Hu

    2011-01-01

    A conventional X-ray difFractometer has been used to determine the -y/y' lattice misfit and γ' volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by w-20 scan were used to determine the γ/γ' lattice misfit and γ' volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ' lattice misfit and ~/r volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ' lattice misfit and γ' volume fraction of the experimental alloy are approximately-0.2% and 70%, respectively. Furthermore, the γ' volume fraction calculated by atom microprobe (AP) data is also basically consistent with the experimental results.

  4. The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Maier, R. D.

    1982-01-01

    Constant load creep rupture tests were performed on MAR-M247 single crystals at 724 MPa and 774 C where the effect of anisotropy is prominent. The initial orientations of the specimens as well as the final orientations of selected crystals after stress rupture testing were determined by the Laue back-reflection X-ray technique. The stress rupture lives of the MAR-M247 single crystals were found to be largely determined by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited the shortest stress rupture lives, whereas crystals requiring little or no rotations exhibited the lowest minimum creep rates, and consequently, the longest stress rupture lives.

  5. Orientation dependence of the stress rupture properties of Nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.

    1981-01-01

    The influence of orientation of the stress rupture behavior of Mar-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because steady-state creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently a short stress rupture life. A unified analysis was attained for the stress rupture behavior of the Mar-M247 single crystals tested in this study at 774 C and that of the Mar-M200 single crystals tested in a prior study at 760 C. In this analysis, the standard 001-011-111 stereographic triangle was divided into several regions of crystallographic orientation which were rank ordered according to stress rupture life for this temperature regime. This plot indicates that those crystals having orientations within about 25 deg of the 001 exhibited significantly longer lives when their orientations were closer to the 001-011 boundary of the stereographic triangle than to the 001-111 boundary.

  6. Orientation dependence of the stress rupture properties of Nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.

    1981-05-01

    The influence of orientation of the stress rupture behavior of Mar-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because steady-state creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently a short stress rupture life. A unified analysis was attained for the stress rupture behavior of the Mar-M247 single crystals tested in this study at 774 C and that of the Mar-M200 single crystals tested in a prior study at 760 C. In this analysis, the standard 001-011-111 stereographic triangle was divided into several regions of crystallographic orientation which were rank ordered according to stress rupture life for this temperature regime. This plot indicates that those crystals having orientations within about 25 deg of the 001 exhibited significantly longer lives when their orientations were closer to the 001-011 boundary of the stereographic triangle than to the 001-111 boundary.

  7. The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, Rebecca A.; Maier, Ralph D.

    1982-10-01

    The influence of orientation on the stress rapture properties of MAR-M247 single crystals was studied. Stress rupture tests were performed at 724 MPa and 774 °C where the effect of anisotropy is prominent. The mechanical behavior of the single crystals was rationalized on the basis of the Schmid factors for the operative slip systems and the lattice rotations which the crystals underwent during deformation. The stress rupture lives at 774 °C were found to be greatly influenced by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited a large primary creep strain, a large effective stress level at the onset of steady-state creep, and consequently, a short stress rupture life. Those crystals having orientations within about 25° of the [001] exhibited significantly longer lives when their orientations were closer to the [001]-[011] boundary of the stereographic triangle than to the [001]-[1l 1] boundary, because they required smaller rotations to produce intersecting slip and the onset of second-stage creep. Thus, the direction off the [001], as well as the number of degrees off the [001], has a major influence on the stress rapture lives of single crystals in this temperature regime.

  8. Influence of molybdenum on the creep properties of nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Nathal, M. V.; Pearson, D. D.

    1990-01-01

    The Mo content of an alloy series based on Ni-6 wt pct Al-6 wt pct Ta was systematically varied from 9.8 to 14.6 wt pct, in order to ascertain the influence of Mo on the creep properties of single crystals. The optimum initial gamma-gamma prime microstructure for raft development and creep strength was established in each alloy before testing. It was found that, as the Mo content increased from 9.8 to 14.0 percent, the magnitude of the lattice mismatch increased; upon reaching 14.6 percent, a degradation of mechanical properties occurred due to the precipitation of a third phase. These results suggest that small refractory metal content and initial gamma-prime variations can profoundly affect mechanical properties.

  9. Effect of Surface Preparation on the 815°C Oxidation of Single-Crystal Nickel-Based Superalloys

    Science.gov (United States)

    Sudbrack, Chantal K.; Beckett, Devon L.; MacKay, Rebecca A.

    2015-11-01

    A primary application for single-crystal superalloys has been jet engine turbine blades, where operation temperatures reach well above 1000°C. The NASA Glenn Research Center is considering use of single-crystal alloys for future, lower temperature application in the rims of jet engine turbine disks. Mechanical and environmental properties required for potential disk rim operation at 815°C are being examined, including the oxidation and corrosion behavior, where there is little documentation at intermediate temperatures. In this study, single-crystal superalloys, LDS-1101+Hf and CMSX-4+Y, were prepared with different surface finishes and compared after isothermal and cyclic oxidation exposures. Surface finish has a clear effect on oxide formation at 815°C. Machined low-stress ground surfaces after exposure for 440 h produce thin Al2O3 external scales, which is consistent with higher temperature oxidation, whereas polished surfaces with a mirror finish yield much thicker NiO external scales with subscale of Cr2O3-spinel-Al2O3, which may offer less reliable oxidation resistance. Additional experiments separate the roles of cold-work, localized deformation, and the extent of polishing and surface roughness on oxide formation.

  10. In Situ Imaging of High Cycle Fatigue Crack Growth in Single Crystal Nickel-Base Superalloys by Synchrotron X-Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Liu; Husseini, Naji S.; Torbet, Christopher J.; Kumah, Divine P.; Clarke, Roy; Pollock, Tresa M.; Jones, J.Wayne (Michigan)

    2008-05-01

    A novel X-ray synchrotron radiation approach is described for real-time imaging of the initiation and growth of fatigue cracks during ultrasonic fatigue (f=20 kHz). We report here on new insights on single crystal nickel-base superalloys gained with this approach. A portable ultrasonic fatigue instrument has been designed that can be installed at a high-brilliance X-ray beamline. With a load line and fatigue specimen configuration, this instrument produces stable fatigue crack propagation for specimens as thin as 150 {mu}m. The in situ cyclic loading/imaging system has been used initially to image real-time crystallographic fatigue and crack growth under positive mean axial stress in the turbine blade alloy CMSX-4.

  11. Recent breakthroughs in nickel base superalloys

    OpenAIRE

    Honnorat, Y.

    1993-01-01

    Meanwhile the considerable amount of results acquired since more than sixty years in the study of this class of materials, the pre-eminence of nickel base superalloys in the gas turbine engineering, which is a domain in constant evolution, drives the significant progresses accomplished along the five last years. The knowledge, each day more precisely known, of the working conditions of the parts, the continuous increase of the computer capacity and the progressive sophistication of the design...

  12. Factors which influence directional coarsening of Gamma prime during creep in nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined as a function of time during creep at 982 C in 001 oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80 pct., the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The effects of initial microstructure and alloy composition of raft development and creep properties were investigated. Directional coarsening of gamma prime begins during primary creep and continues well after the onset of second state creep. The thickness of the rafts remains constant up through the onset of tertiary creep a clear indication of the stability of the finely-spaced gamma/gamma prime lamellar structure. The thickness of the rafts which formed was equal to the initial gamma prime size which was present prior to testing. The single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma/gamma prime interfaces per unit volume of material. Reducing the Mo content by only 0.73 wt. pct. increased the creep life by a factor of three, because the precipitation of a third phase was eliminated.

  13. Factors which influence directional coarsening of gamma-prime during creep in nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined as a function of the time during creep at 982 C in 001 oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80 pct., the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The effects of initial microstructure and alloy composition of raft development and creep properties were investigated. Directional coarsening of gamma prime begins during primary creep and continues well after the onset of second state creep. The thickness of the rafts remains constant up through the onset of tertiary creep, a clear indication of the stability of the finely-spaced gamma/gamma prime lamellar structure. The thickness of the rafts which formed was equal to the initial gamma prime size which was present prior to testing. The single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma/gamma prime interfaces per unit volume of material. Reducing the Mo content by only 0.73 wt. pct. increased the creep life by a factor of three, because the precipitation of a third phase was eliminated.

  14. NUMERICAL STUDY OF THE NOTCH EFFECT ON THE CREEP BEHAVIOR AND LIFE OF NICKEL-BASE SINGLE CRYSTAL SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    Q.M. Yu; Z.F. Yue

    2004-01-01

    Numerical calculations of creep damage development and life behavior of circular notched specimens of nickel-base single crystal had been performed. The creep stress distributions depend on the specimen geometry. For a small notch radius, von Mises stress has an especial distribution. The damage distribution is greatly influenced by the notch depth, notch radius as well as notch type. The creep crack initiation place is different for each notched specimen. The characteristics of notch strengthening and notch weakening depend on the notch radius and notch type. For the same notch type,the creep rupture lives decrease with the decreasing of notch radius. A creep life model has been presented for the multiaxial stress states based on the crystallographic slip system theory.

  15. The contrasting roles of creep and stress relaxation in the time-dependent deformation during in-situ cooling of a nickel-base single crystal superalloy.

    Science.gov (United States)

    Panwisawas, Chinnapat; D'Souza, Neil; Collins, David M; Bhowmik, Ayan

    2017-09-11

    Time dependent plastic deformation in a single crystal nickel-base superalloy during cooling from casting relevant temperatures has been studied using a combination of in-situ neutron diffraction, transmission electron microscopy and modelling. Visco-plastic deformation during cooling was found to be dependent on the stress and constraints imposed to component contraction during cooling, which mechanistically comprises creep and stress relaxation. Creep results in progressive work hardening with dislocations shearing the γ' precipitates, a high dislocation density in the γ channels and near the γ/γ' interface and precipitate shearing. When macroscopic contraction is restricted, relaxation dominates. This leads to work softening from a decreased dislocation density and the presence of long segment stacking faults in γ phase. Changes in lattice strains occur to a similar magnitude in both the γ and γ' phases during stress relaxation, while in creep there is no clear monotonic trend in lattice strain in the γ phase, but only a marginal increase in the γ' precipitates. Using a visco-plastic law derived from in-situ experiments, the experimentally measured and calculated stresses during cooling show a good agreement when creep predominates. However, when stress relaxation dominates accounting for the decrease in dislocation density during cooling is essential.

  16. Nickel-Based Superalloy Resists Embrittlement by Hydrogen

    Science.gov (United States)

    Lee, Jonathan; Chen, PoShou

    2008-01-01

    A nickel-based superalloy that resists embrittlement by hydrogen more strongly than does nickel alloy 718 has been developed. Nickel alloy 718 is the most widely used superalloy. It has excellent strength and resistance to corrosion as well as acceptably high ductility, and is recognized as the best alloy for many high-temperature applications. However, nickel alloy 718 is susceptible to embrittlement by hydrogen and to delayed failure and reduced tensile properties in gaseous hydrogen. The greater resistance of the present nickel-based superalloy to adverse effects of hydrogen makes this alloy a superior alternative to nickel alloy 718 for applications that involve production, transfer, and storage of hydrogen, thereby potentially contributing to the commercial viability of hydrogen as a clean-burning fuel. The table shows the composition of the present improved nickel-based superalloy in comparison with that of nickel alloy 718. This composition was chosen to obtain high resistance to embrittlement by hydrogen while maintaining high strength and exceptional resistance to oxidation and corrosion. The most novel property of this alloy is that it resists embrittlement by hydrogen while retaining tensile strength greater than 175 kpsi (greater than 1.2 GPa). This alloy exhibits a tensile elongation of more than 20 percent in hydrogen at a pressure of 5 kpsi (approximately equal to 34 MPa) without loss of ductility. This amount of elongation corresponds to 50 percent more ductility than that exhibited by nickel alloy 718 under the same test conditions.

  17. Deformation and Damage Mechanism of a 4.5% Re-containing Nickel-based Single Crystal Superalloy During Creep at 980℃

    Directory of Open Access Journals (Sweden)

    SHU De-long

    2017-01-01

    Full Text Available By means of creep property measurements and microstructure observations,an investigation has been made into creep behaviors,deformation and damage mechanism of a 4.5%(mass fraction,the same below Re-containing,nickel-based single crystal superalloy at 980℃.Results show that,under the condition of 980℃/300MPa,the creep life of 4.5% Re alloy is 169h.In the initial stage of creep,the cubical γ'phase in alloy is transformed into the N-type rafted structure perpendicular to the stress axis.During the steady stage creep,the deformation mechanism of the alloy is dislocations slipping in γ matrix and climbing over the rafted γ'phase.In the last stage of creep,the deformation mechanism of alloy is dislocations slipping in γ matrix and shearing into the rafted γ'phase.On the one hand,the γ matrix channels with narrower feature increases the resistance of dislocations slipping;on the other hand,the super-dislocations shearing into the rafted γ'phase may cross-slip from{111}plane to{100}plane to form the dislocation configuration of K-W locks,which may restrain the slipping and cross-slipping of dislocations to improve the creep resistance of alloy.Moreover,the alternate activation of the primary/secondary slipping dislocations results in the twisting of the rafted γ'phase to promote the initiation of the cracks on the γ'/γ interfaces,and as the creep goes on,the cracks propagate along the direction perpendicular to the direction of stress axis,up to creep fracture,which is thought to be the fracture mechanism of the alloy during creep.

  18. Synthesis of alpha-aluminum oxide and hafnium-doped beta-nickel aluminide coatings on single crystal nickel-based superalloy by chemical vapor deposition

    Science.gov (United States)

    He, Limin

    Thermal barrier coatings (TBCs) are widely used for air-cooled turbine components in advanced aircraft engines and power generation systems. The dominant failure mode observed in TBCs is progressive fracture of the metal-oxide interface upon oxidation and thermal cycling. Two potential coating methods for improving TBC performance were studied: (1) preparing a high-quality alpha-Al 2O3 coating layer on the surface of a single crystal Ni-based superalloy (Rene N5) to extend the oxidative stability of the interface and (2) doping beta-NiAl bond coating with a small amount of Hf to improve the adhesion of thermally grown oxide (TGO) at the interface. In the first coating method, a novel chemical vapor deposition (CVD) procedure was developed using AlCl3, CO2 and H 2 as precursors. A critical part of this procedure was a short-time pre-oxidation step (1 min) with CO2 and H2 in the CVD chamber, prior to introducing the AlCl3, vapor. Without this pre-oxidation step, extensive whisker formation was observed on the alloy surface. Characterization results showed that the pre-oxidation step resulted in the formation of a continuous oxide layer (˜50 nm) on the alloy surface. The outer part of this layer (˜20 nm) appeared to contain mixed oxides whereas the inner part (˜30 nm) consisted of alpha-Al2O3 as a dominant major phase and theta-Al2O3 as a minor phase. It appeared that the preferential nucleation of beta-Al2O3 in the pre-oxidized layer was promoted by: (1) rapid heating (˜10 sec) of the alloy surface to the temperature region, where alpha-Al 2O3 was expected to nucleate instead of metastable Al 2O3 phases, (2) the low oxygen pressure environment of the pre-oxidation step which kept the rate of oxidation low, and (3) contamination of the CVD chamber with HfCl4. It appeared that the role of HfCl 4 was to enhance the preferential nucleation of alpha-Al2O 3 in the pre-oxidized layer. In our second coating method, we utilized the dynamic versatility of CVD as an avenue

  19. Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy

    Science.gov (United States)

    Adebajo, O. J.; Ojo, O. A.

    2017-01-01

    Electrochemical analysis of corrosion performance of a transient liquid phase (TLP) bonded nickel-based superalloy was performed. The TLP bonding process resulted in significant reduction in corrosion resistance due to the formation of non-equilibrium solidification reaction micro-constituents within the joint region. The corrosion resistance degradation is completely eliminated through a new application of composite interlayer that had been previously considered unusable for joining single-crystal superalloys. The effectiveness of the new approach becomes more pronounced as the severity of environment increases.

  20. Influence of composition on the microstructure and mechanical properties of a nickel-base superalloy single crystal

    Science.gov (United States)

    Nathal, M. V.; Ebert, L. J.

    1984-01-01

    The effects of cobalt, tantaium, and tungsten contents on the microstructure and mechanical properties of single crystal Mar-M247 were investigated. Elevated temperature tensile and creep-rupture properties of 001 oriented single crystals were related to microstructural features of the alloys. Substitution of Ni for Co in the high refractory metal alloys increased the lattice mismatch, which was considered to be the cause of the increases in tensile and creep strength. Substitution of Ni for Ta caused large decreases in tensile strength and creep life, consistent with decreases in gamma prime volume fraction, lattice mismatch, and solid solution hardening. Substitution of W for Ta resulted in decreased life at high stresses, which was related to small decreases in mismatch and volume fraction. However, the W substitution resulted in improved life at low stresses, which was related to solid solution strengthening by W.

  1. Hot Corrosion of Coated Single Crystal Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Simms, N. J.; Encinas-Oropesa, A.; Nicholls, J.R. [Cranfield University, Power Generation Technology Centre, Cranfield, Beds, MK43 0AL (United Kingdom)

    2004-07-01

    Gas turbines are at the heart of many modern power systems, with combined cycle power generation utilising natural gas being an effective way of reducing environmental emissions compared to conventional pulverized coal fired plants. The development of gas turbine technology has been focused on increasing its efficiency. However, the lives of the hot gas path components within these gas turbines are also critical to the viability of the power systems. Single crystal superalloys have been developed for use with clean fuel/air but are now being used in industrial gas turbines that may need to run with dirtier fuel/air. Indeed, gas turbine based power systems are being evaluated in which solid fuels (e.g. coal and/or biomass) are gasified to produce fuel gases, which introduces the potential for significant corrosive and erosive damage to gas turbine blades and vanes. The performance of these materials, with coatings, has to be determined before they can be used with confidence in dirtier fuel environments. This paper reports results from a series of laboratory tests carried out using the 'deposit replenishment' technique to investigate the sensitivity of candidate materials to exposure conditions anticipated in such gas turbines. The materials investigated have included CMSX-4 and SC{sup 2}-B (both bare and with Pt-Al and Amdry 997 coatings) as well as conventional nickel based superalloys such as IN738LC for comparison. The exposure conditions within the laboratory tests have covered ranges of SO{sub x} (50 and 500 vpm) and HCl (0 and 500 vpm) in air, as well as 4/1 (Na/K){sub 2}SO{sub 4} deposits, with deposition fluxes of 1.5, 5 and 15 {mu}g/cm{sup 2}/h, for periods of up to 500 hours at 700 and 900 deg. C. Data on the performance of materials has been obtained using dimensional metrology: pre-exposure contact measurements and post-exposure measurements of features on polished cross-sections. These measurement methods allow distributions of damage data to

  2. Automated Identification and Characterization of Secondary & Tertiary gamma’ Precipitates in Nickel-Based Superalloys (PREPRINT)

    Science.gov (United States)

    2010-01-01

    METHODOLOGY A nickel-based superalloy sample (Rene88DT) was cut from a forged disc developed under a Defense Advanced Research Projects Agency funded...AFRL-RX-WP-TP-2010-4064 AUTOMATED IDENTIFICATION AND CHARACTERIZATION OF SECONDARY & TERTIARY γ’ PRECIPITATES IN NICKEL-BASED SUPERALLOYS ...AUTOMATED IDENTIFICATION AND CHARACTERIZATION OF SECONDARY & TERTIARY γ’ PRECIPITATES IN NICKEL-BASED SUPERALLOYS (PREPRINT) 5a. CONTRACT NUMBER In

  3. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-04-01

    Full Text Available The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possibility of using certainmixtures as potential inoculating additives for the volume modification of nickel and cobalt superalloys. A characteristic feature of these alloys is the formation of a detrimental structure containing very large columnar crystal, present even in castings of a very high solidification rate. It has been proved that the inoculant most effective in the formation of the structure of equiaxial grains is the inoculant based on cobalt aluminate, colloidal silica and powdered aluminium.

  4. 元素Re对镍基单晶合金中温蠕变行为的影响%Influence of element Re on intermediate temperature creep behavior of single crystal nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    田素贵; 舒德龙; 曾征; 刘臣; 郭忠革

    2013-01-01

    通过对有/无元素Re合金进行蠕变曲线测定及组织形貌观察,研究了元素Re对镍基单晶合金中温蠕变行为的影响.结果表明:与无Re合金相比,4.5% Re合金在中温/高应力条件下具有良好的蠕变抗力.蠕变期间无Re合金中的γ'相转变成串状,而4.5Re合金中的γ'相仍保持立方体形貌,有/无元素Re合金在中温蠕变期间的变形机制均为超位错剪切γ'相,切入γ'相的超位错可在{111}面滑移,或在{111}面分解形成{112}超肖克莱不全位错+(SISF)的位错组态,抑制其交滑移;其中,4.5% Re合金中切入Y'相的超位错可由{111}面交滑移至(100)面,形成K-W锁,是使合金具有良好蠕变抗力的重要原因之一.%Influence of element Re on intermediate temperature creep behavior of the single crystal nickel-base superalloy was studied by means of creep curve measurement and microstructure observation.The results show that compared to free-Re superalloy,4.5% Re superalloy exhibits a better creep resistance under the conditions of medium temperature and high stress.During creep at intermediate temperature,the cubical γ' phase in free-Re superalloy is transformed into the bunch-like structure,and large numbers of γ' phase in 4.5% Re superalloy keep still the cubical configuration.The deformation mechanisms of the free/with Re superalloys during creep are that the slipping of (1/2) dislocations is activated in the γmatrix channels and super-dislocations shear into the γ' phase,and the super-dislocations shearing into the γ' phase both slip on {111} planes and decompose to form the configuration of (1/3) superShockleys partials plus the stacking fault,which may restrain the cross-slipping of dislocations.Therein,the super-dislocations shearing into the γ' phase in 4.5% Re superalloy may cross slip from { 111} to {100} planes to form K-W locks which may restrain the slipping of dislocations due to the non-plane core structure of them,this is

  5. Morphological changes of gamma prime precipitates in nickel-base superalloy single crystals. Ph.D. Thesis - Case Western Reserve Univ., May 1984

    Science.gov (United States)

    Mackay, R. A.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined during tensile creep at temperatures between 927 and 1038 C in 001-oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80%, the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The dimensions of the gamma and gamma prime phases were measured as directional coarsening developed in an attempt to trace the changing morphology under various stress levels. In addition, the effects of initial microstructure, as well as slight compositional variations, were related to raft development and creep properties. The results showed that directional coarsening of gamma prime began during primary creep, and under certain conditions, continued to develop after the onset of steady-state creep. The length of the rafts increased linearly with time up to a plateau region. The thickness of the rafts, however, remained equal to the initial gamma prime size at least up through the onset of tertiary creep; this is a clear indication of the stability of the finely-spaced gamma-gamma prime lamellar structure. It was found that the single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma-gamma prime interfaces per unit volume of material.

  6. Continuous Extraction of Nickel from Superalloy Scraps Using Zinc Circulation

    Science.gov (United States)

    Yagi, Ryohei; Okabe, Toru H.

    2017-02-01

    A novel technique for the continuous extraction of nickel (Ni) from Ni-based superalloy scraps using molten zinc (Zn) has been proposed, and its feasibility was experimentally demonstrated. The newly developed approach allows for extraction of Ni metal directly from superalloy scraps with simultaneous separation of the Zn from the resulting Zn-Ni alloy. The optimal conditions for the extraction of Ni and separation of valuable elements such as rhenium (Re), tantalum (Ta), and tungsten (W) were determined by varying major process parameters including the reaction time and configuration of the reaction chamber. The proposed method has been successfully utilized for the production of the superalloy containing 62.8 mass pct of Ni and 15.5 mass pct of refractory metals (Re, W, and Ta). Under certain conditions, 41 pct of the Ni contained in the superalloy could be extracted at 1173 K (900 °C) over 48 hours, producing an alloy containing 84.0 mass pct of Ni and 0.2 mass pct of the refractory metals.

  7. 3D imaging using X-Ray tomography and SEM combined FIB to study non isothermal creep damage of (111) oriented samples of γ / γ ′ nickel base single crystal superalloy MC2

    KAUST Repository

    Jouiad, Mustapha

    2012-01-01

    An unprecedented investigation consisting of the association of X-Ray tomography and Scanning Electron Microscopy combined with Focus Ion Beam (SEM-FIB) is conducted to perform a 3D reconstruction imaging. These techniques are applied to study the non-isothermal creep behavior of close (111) oriented samples of MC2 nickel base superalloys single crystal. The issue here is to develop a strategy to come out with the 3D rafting of γ\\' particles and its interaction whether with dislocation structures or/and with the preexisting voids. This characterization is uncommonly performed away from the conventional studied orientation [001] in order to feed the viscoplastic modeling leading to its improvement by taking into account the crystal anisotropy. The creep tests were performed at two different conditions: classical isothermal tests at 1050°C under 140 MPa and a non isothermal creep test consisting of one overheating at 1200°C and 30 seconds dwell time during the isothermal creep life. The X-Ray tomography shows a great deformation heterogeneity that is pronounced for the non-isothermal tested samples. This deformation localization seems to be linked to the preexisting voids. Nevertheless, for both tested samples, the voids coalescence is the precursor of the observed damage leading to failure. SEM-FIB investigation by means of slice and view technique gives 3D views of the rafted γ\\' particles and shows that γ corridors evolution seems to be the main creep rate controlling parameter. © 2012 Trans Tech Publications, Switzerland.

  8. Creep behavior of Re-free nickel-based single crystal superalloy at intermediate temperature%无Re镍基单晶合金的中温蠕变行为

    Institute of Scientific and Technical Information of China (English)

    田素贵; 薛永超; 曾征; 舒德龙; 郭忠革; 谢君

    2013-01-01

    通过中温蠕变性能测试、组织形貌观察及位错组态的衍衬分析,研究无 Re 镍基单晶合金的蠕变行为与变形机制。结果表明:在760℃、750 MPa条件下,合金具有良好的蠕变抗力及较长的蠕变寿命,蠕变期间,合金中的γ′相仅发生粗化,未发生筏形化转变。合金在蠕变初期的变形机制是(1/2)〈110〉位错在基体通道的{111}八面体滑移系中运动,蠕变位错可发生单取向滑移、双取向滑移和交滑移;随着蠕变进入后期,合金的应变增大,其变形机制是〈110〉位错在基体中运动和剪切进入γ′相,其中,基体中的位错发生扭曲,而部分剪切进入γ′相的〈110〉超位错发生分解,形成〈112〉肖克莱不全位错+层错的位错组态,可抑制位错的交滑移,使合金具有较好的蠕变抗力。%By means of creep property measurement at intermediate temperature, microstructure observation and contrast analysis of dislocation configuration, the creep behavior and deformation mechanism of Re-free nickel-based single crystal superalloy at intermediate temperature were investigated. The results show that the alloy displays a better creep resistance and long creep life at 760℃, 750 MPa. During creep at intermediate temperature, the coarsening of the cubicalγ′ phase occurs, and no rafting transformation of γ′ phase is detected. The deformation mechanism of the superalloy during initial creep is the slipping of (1/2) dislocations with single oriented, double oriented and cross-slipping features activated on the octahedral systems in theγmatrix channels. The strain of the alloy increases as the creep enters latter stage, the deformation mechanism of the superalloy is that 〈110〉 dislocations slipping in theγmatrix and shearing enter into the cubical γ′ phase. Thereinto, the twisting of dislocations in the matrix occurs, and some 〈110〉super-dislocations shearing into γ′ phase

  9. Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

    Science.gov (United States)

    Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

    2017-02-01

    Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

  10. Thermomechanical fatigue in single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Moverare Johan J.

    2014-01-01

    Full Text Available Thermomechanical fatigue (TMF is a mechanism of deformation which is growing in importance due to the efficiency of modern cooling systems and the manner in which turbines and associated turbomachinery are now being operated. Unfortunately, at the present time, relatively little research has been carried out particularly on TMF of single crystal (SX superalloys, probably because the testing is significantly more challenging than the more standard creep and low cycle fatigue (LCF cases; the scarcity and relative expense of the material are additional factors. In this paper, the authors summarise their experiences on the TMF testing of SX superalloys, built up over several years. Emphasis is placed upon describing: (i the nature of the testing method, the challenges involved in ensuring that an given testing methodology is representative of engine conditions (ii the behaviour of a typical Re-containing second generation alloy such as CMSX-4, and its differing performance in out-of-phase/in-phase loading and crystallographic orientation and (iii the differences in behaviour displayed by the Re-containing alloys and new Re-free variants such as STAL15. It is demonstrated that the Re-containing superalloys are prone to different degradation mechanisms involving for example microtwinning, TCP precipitation and recrystallisation. The performance of STAL15 is not too inferior to alloys such as CMSX-4, suggesting that creep resistance itself does not correlate strongly with resistance to TMF. The implications for alloy design efforts are discussed.

  11. Property Enrichment of Aged Nickel Base Superalloy Supercast 247A

    Directory of Open Access Journals (Sweden)

    Lavakumar Avala

    2013-12-01

    Full Text Available The commercial nickel-base superalloy Supercast 247A can be used for applications in which is required high mechanical strength and corrosion resistance at elevated temperatures, such as turbine blades and automotive turbocharger rotors. The mechanical properties are totally connected to the morphology, size and distribution of γ' phase and carbides. In order to improve the mechanical properties, the material is subjected to solution and aging heat treatment, to raise the volume fraction of γ' phase in the matrix and to form carbides at grain boundaries. In the present study the Supercast 247A superalloy was remelted and cast to obtain the desired polycrystalline test bars by controlling casting parameters, followed by the investigation of precipitation morphology and mechanical properties with respect to solution treatment and aging treatment. The experimental results show that by well controlled casting parameters the Supercast 247A owns excellent castability to form a superalloy with fine grain structure, resistance to indentation as well as superior strength.

  12. Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. Mills

    2009-03-05

    Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.

  13. Phase transformations and microstructure of IN-713C nickel superalloy

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-04-01

    Full Text Available The study presents the results of investigations of phase transformations taking place during melting and solidification and ofmicrostructural examinations carried out on the family of IN 713C nickel superalloys. Examinations were carried out by the method ofthermal analysis (ATD and differential scanning calorimetry (DSC. It has been concluded that the method of thermal analysis (ATDenables more precise assessment of the precipitation of the primary phases of a low value of the solidification enthalpy. The advantage ofDSC is the possibility of determination of the value of the heat (enthalpy of phase transformations during alloy melting and solidification. The measured parameters of Tlik and Tsol are comparable for both methods. Microstructural examinations have confirmed the phenomena accompanying phase transformations, i.e. the precipitation of primary carbides, the solidification of y' phase matrix and carbide eutectic, and the formation of y’ phase in solid state.

  14. Macro- and microhardness of IN-713C nickel superalloy constituents

    Directory of Open Access Journals (Sweden)

    F. Binczyk

    2009-10-01

    Full Text Available The results of investigations of the effect of modification and cooling rate on the macrohardness of castings and microhardness of phase constituents in IN-713C nickel superalloy were described. As an inoculant, cobalt aluminate CoAl2O4 in composition with aluminium powder and colloidal silica was used. Changes in the cooling rate were obtained using a cast stepped test piece with steps of 6, 11 and 17 mm thickness. Macrohardness of the cast test piece steps was measured by Brinell technique, while Vickers method was used to measure the microhardness of γ and γ’ phases present in the alloy matrix, as well as the hardness of eutectic carbide precipitates.A significant effect of the cooling rate and modification treatment on the results of the measurements was stated, and difficulties in performing correctly the microhardness measurements due to the precipitates dimensions, especially after the modification treatment, were highlighted.

  15. Creep curve modelling of a conventionally cast nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Lupinc, V.; Maldini, M. [CNR - IENI, Milan (Italy); Poggio, E.; Vacchieri, E. [Ansaldo Energia S.p.A., Genoa (Italy)

    2010-07-01

    Constant load creep tests on Rene 80, a nickel base superalloy for gas turbine blade application, were run in the temperature interval 800-950 C with applied stresses producing rupture times up to 1000 h. Creep curves are generally dominated by a long accelerating/tertiary creep that follows a relatively small decelerating/primary creep. No steady state stage has been observed. Analysis of the creep curves has shown that a single damage parameter can describe the long accelerating/tertiary state in the explored temperature range. The damage appears to be dependent on the accumulated creep strain and, as a first approximation, independent on the applied stress and temperature. The whole creep curve, primary and tertiary stages, has been modelled by a simple set of coupled differential equations obtained using the formalism of the Continuum Damage Mechanics. The proposed set of equations has an analytical solution, strain vs. time, for creep curves at constant temperature and stress. (orig.)

  16. Recovery of Nickel from Nickel-Based Superalloy Scraps by Utilizing Molten Zinc

    Science.gov (United States)

    Yagi, Ryohei; Okabe, Toru H.

    2017-02-01

    With the purpose of developing a new process for recycling nickel (Ni) directly from superalloy scraps, a fundamental study on the extraction and separation of Ni was carried out using molten zinc (Zn) as the extraction medium. In order to examine the reaction between molten Zn and the Ni-based superalloy, superalloy samples and Zn shots were heated at 1173 K (900 °C) for 6 hours. After heating, the superalloy samples fully reacted with Zn and dissolved in molten Zn. The Zn-alloyed sample obtained by slow cooling consisted of two separated upper and lower phases. In the upper part of the sample, only Zn and the Zn-Ni alloys were found; in the lower part, an intermetallic alloy consisting of refractory metals such as rhenium (Re) and tantalum (Ta) was found. This result shows that Ni and refractory metals contained in the scrap can be separated by utilizing the density differences between the Zn-Ni alloy and the refractory metals in molten Zn. Vacuum treatment of the upper part of the Zn-alloyed sample at 1173 K (900 °C) reduced the concentration of Zn in the sample from 97.0 to 0.4 mass pct. After Zn removal, a Ni alloy containing Ni with a purity of 85.3 to 86.1 mass pct and negligible quantities (scraps without the consumption of Zn or the generation of toxic wastes solutions.

  17. Microstructural studies of carbides in MAR-M247 nickel-based superalloy

    Science.gov (United States)

    Szczotok, A.; Rodak, K.

    2012-05-01

    Carbides play an important role in the strengthening of microstructures of nickel-based superalloys. Grain boundary carbides prevent or retard grain-boundary sliding and make the grain boundary stronger. Carbides can also tie up certain elements that would otherwise promote phase instability during service. Various types of carbides are possible in the microstructure of nickel-based superalloys, depending on the superalloy composition and processing. In this paper, scanning electron and scanning transmission electron microscopy studies of carbides occurring in the microstructure of polycrystalline MAR-M247 nickel-based superalloy were carried out. In the present work, MC and M23C6 carbides in the MAR-M247 microstructure were examined.

  18. The mechanisms and temperature dependence of superlattice stacking fault formation in the single-crystal superalloy PWA 1480

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1991-01-01

    The mechanism of the formation of superlattice staking faults in the single-crystal nickel-base superalloy PWA 1480 was investigated by observing deformation microstructures in the superalloy single crystals in the temperature range 20-1100 C. Results showed that, in addition to superlattice stacking faults observed after slow strain rate deformation at temperatures from 700 to 950 C, a high-density of superlattice staking faults formed after deformation at 200 C and below. The mechanisms of fault formation, which are different in the high- and the low-temperature regimes, are discussed.

  19. Dynamic precipitation of nickel-based superalloys undergoing severe deformation below the solvus temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nowotnik, Andrzej; Rokicki, Pawel; Mrowka-Nowotnik, Grazyna; Sieniawski, Jan [Rzeszow Univ. of Technology (Poland). Dept. of Material Science

    2015-07-15

    The authors performed uniaxial compression tests of nickel-based superalloys: single crystal CMSX-4, also precipitation hardened; Inconel 718 and X750, at temperatures below the γ' solvus, in order to study the effect of temperature and strain rate on their flow stress and microstructural development. On the basis of the obtained flow stress values, the activation energy of a high-temperature deformation process was estimated. Microstructural observations of the deformed samples at high temperatures, previously solution heat treated and aged CMSX-4 and Inconel alloys revealed non-uniform deformation effects. Distribution of either molybdenum- or niobium-rich carbides was found to be affected by localized flow within the investigated strain range at relatively low deformation temperatures, 720-850 C. Microstructural examination of the alloys also showed that shear banding and cavity growth were responsible for the decrease in flow stress and a specimen fracture at larger strains.

  20. Temperature dependence of gamma-gamma prime lattice mismatch in nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.; Garlick, R. G.

    1985-01-01

    High temperature X-ray diffraction techniques were used to determine the gamma-gamma prime lattice mismatch of three different nickel-base superalloys at temperatures between 18 and 1000 C. The measurements were performed on oriented single-crystal disks which had been aged to produce a semicoherent gamma-gamma prime structure. The thermal expansion of the lattice parameters of the gamma and gamma-prime phases was described by a second-order polynomial expression. The expansion of the gamma-prime phase was consistently smaller than that of the gamma phase, which caused the lattice mismatch to become more negative at higher temperatures. It was also shown that high values of lattice mismatch resulted in increased rates of directional gamma-prime coarsening during elevated temperature creep exposure.

  1. THE ROLE OF NIOBIUM IN NICKEL-BASED SUPERALLOYS AND CHARACTERIZATION OF PM ALLOY EP741NP

    Institute of Scientific and Technical Information of China (English)

    T. Carneiro; J. Radavich; D. Furrer

    2005-01-01

    The role of niobium in nickel-based superalloys is reviewed. The importance of niobium as a strengthener is discussed. New developments in nickel-based superalloys are also briefly mentioned, including some results that show improved resistance to sulfidation by niobium. Research results from a current program on the role of niobium in the Russian powder metallurgy alloy EP741NP are presented. Future research plans on the role of niobium in superalloys are also discussed.

  2. A Coupled Creep Plasticity Model for Residual Stress Relaxation of a Shot Peened Nickel-Base Superalloy (Postprint)

    Science.gov (United States)

    2008-09-01

    McLean, M. “Tension- Compression creep asymmetry in a turbine disc superalloy : roles of internal stress and thermal ageing,” Acta Materialia, 52, 2004...AFRL-RX-WP-TP-2009-4156 A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT...SUBTITLE A COUPLED CREEP PLASTICITY MODEL FOR RESIDUAL STRESS RELAXATION OF A SHOT PEENED NICKEL-BASE SUPERALLOY (POSTPRINT) 5a. CONTRACT NUMBER

  3. Gamma Prime Morphology and Creep Properties of Nickel Based Superalloys With Platinum Group Metal Additions (Preprint)

    Science.gov (United States)

    2008-04-01

    creep resistance. Polycrystalline superalloy MAR - M247 can sustain a creep rate of 10-8 s-1 at 982°C at a stress of 172 MPa [44], while the alloys...Nathal, R.D. Maier, and L.J. Ebert, “The Influence of Cobalt on the Tensile and Stress Rupture Properties of the Nickel-Base Superalloy MAR - M247 ,” Metallurgical Transactions A, 13 (A) (1982), 1767-1774.           10

  4. 镍基单晶合金C MS X-6的再结晶行为及热裂倾向∗%Recrystallization and hot cracking tendency of single crystal of nickel-based superalloy CMSX-6

    Institute of Scientific and Technical Information of China (English)

    张力; 赵玉涛; 贾志宏; 梁向锋

    2014-01-01

    The recrystallization behavior of nickel-based single crystal superalloy CMSX-6 at different heat treat-ment temperatures and different magnitude loads were investigated.The result shows that there is no recrystal-lization occurring below 1 150 ℃ for 4 h,while a large number ofγ'particles are precipitated around the eutectic because of the spontaneous segregation ofγ'form elements under the load;As the heat treatment temperature increases,recrystallization of the load influenced area includes three processes:cellular recrystallization around the indentation,recrystallization of the dendritical core and multiple equiaxed grain;When the heat treatment above 1 150 ℃ for 4 h,with the increasing of loading,the area of recrystallization increases distinctly;Last,as the cooling rate increases,the tendency of the heat cracking between the recrystallized grains turns larger and a lot of hot cracking distributed along the recrystallized grain boundary.%在不同热处理温度和载荷下,研究了 CM-SX-6单晶的再结晶现象。结果表明:在低于1150℃×4 h热处理后,没发现再结晶现象,但在载荷的作用下,单晶退火时γ'相形成元素自发偏析,造成大量的大颗粒γ'相在共晶周围析出;随着热处理温度升高,载荷影响区再结晶经历由压痕周围胞状再结晶、枝晶干再结晶、多个等轴再结晶三个阶段;在高于1150℃×4 h热处理时,单晶随着载荷的增加,再结晶的范围和深度明显增大;以及随冷却速率的增加,再结晶晶粒之间的热裂倾向增大,致使大量热裂沿晶界分布。

  5. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    Directory of Open Access Journals (Sweden)

    Sean Davies

    2017-04-01

    Full Text Available The realisation of employing Additive Layer Manufacturing (ALM technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD, each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  6. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Carlos Carvalho Engler-Pinto Júnior

    2014-06-01

    Full Text Available Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF and thermomechanical fatigue (TMF. Test temperatures range from 600°C to 1,000°C. The behavior of the alloy is strongly affected by the temperature variation, especially in the 800°C-1,000°C range. The Ramberg-Osgood equation fits very well the observed isothermal behavior for the whole temperature range. The simplified non-isothermal stress-strain model based on linear plasticity proposed to represent the thermo-mechanical fatigue behavior was able to reproduce the observed behavior for both in-phase and out-of-phase TMF cycling.

  7. Environmental effects of microstructure stability on nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Sah, In Jin

    2011-02-15

    Next generation nuclear reactor VHTR (Very High Temperature gas-cooled Reactor) wants to achieve higher thermal efficiency and hydrogen production. IHX (Intermediate Heat eXchanger) will be exposed to the highest temperature condition among lots of structural components. Solid-solution hardening nickel-base superalloys Alloy 617 and Haynes 230 are expected to use for this applications. Studies on oxidation test and time dependent deformation at 900 .deg. C were conducted before. This study is focused on the microstructure evolution and mechanical properties at other temperature ranges. Furthermore, considering heat treatment history especially cooling rate effects on microstructure evolution, those of two superalloys are cooled down to room temperature by air and furnace. Materials behavior at intermediation temperature ranges from 600-900 .deg. C and diffusion bonding condition (1150 .deg. C) were evaluated. Vicker's hardness test and small-size tensile test were carried out for each specimen at room temperature. Hardness number and tensile strength were higher than any other temperature condition at 700 .deg. C due to gamma prime phases for Alloy 617. As the aluminum contents of Haynes 230 is far less than Alloy 617, there is no big difference for Haynes 230 at intermediate temperature ranges. The value of mechanical property of alloys at 1150 .deg. C air cooling condition was severely decreased and fully ductile fracture was detected for both alloys. On the other hand, the values showed the tendency of return to the intermediate temperature ranges when the specimen was slowly cooled down. Characteristic precipitates along the grain boundaries were detected. There was no other singularity up to 700 .deg. C for Alloy 617. However, lots of tiny M{sub 23}C{sub 6} type carbide were formed after 800 .deg. C heat treatment, and those of carbide got bigger and bigger as the heat treatment temperature increased up to 900 .deg. C. For diffusion bonding temperature

  8. High temperature thermal diffusivity of nickel-based superalloys and intermetallic compounds

    OpenAIRE

    Hazotte, A.; Perrot, B.; Archambault, P

    1993-01-01

    By means of an installation developed in our laboratory, we measured the thermal diffusivity (α) as a function of temperature for several single and polycrystal nickel-based superalloys as well as for different intermetallic compounds with a L12 (Ni3Al, Ni3Si, Ni3Ge, Ni3Fe, Zr3Al, Co3Ti), L10 (TiAl) or B2 (NiAl) structure. In the case of nickel-based superalloys, the experiments pointed out an unexpected but reproductible slope change in the α=f(T) curves at about 750°C, which is not explaine...

  9. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Hamad ur

    2016-07-01

    Nickel and cobalt-based superalloys with a γ-γ{sup '} microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ{sup '} phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  10. Microstructural evolution and castability prediction in newly designed modern third-generation nickel-based superalloys

    Science.gov (United States)

    Naffakh-Moosavy, Homam

    2016-05-01

    The present research aims to establish a quantitative relation between microstructure and chemical composition (i.e., Ti, Al, and Nb) of newly designed nickel-based superalloys. This research attempts to identify an optimum microstructure at which the minimum quantities of γ/γ' and γ/γ″ compounds are achieved and the best castability is predicted. The results demonstrate that the highest quantity of intermetallic eutectics (i.e., 41.5wt%) is formed at 9.8wt% (Ti + Al). A significant quantity of intermetallics formed in superalloy 1 (with a composition of γ - 9.8wt% (Ti + Al)), which can deteriorate its castability. The type and morphology of the eutectics changed and the amount considerably decreased with decreasing Ti + Al content in superalloy 2 (with a composition of γ - 7.6wt% (Ti + Al), 1.5wt% Nb). Thus, it is predicted that the castability would improve for superalloy 2. The same trend was observed for superalloy 4 (with a composition of γ - 3.7wt% (Ti + Al), 4.4wt% Nb). This means that the amount of Laves increases with increasing Nb (to 4.4wt%) and decreasing Ti + Al (to 3.7wt%) in superalloy 4. The best castability was predicted for superalloy 3 (with a composition of γ - 5.7wt% (Ti + Al), 2.8wt% Nb).

  11. The effect of tantalum and carbon on the structure/properties of a single crystal nickel-base superalloy. M.S. Thesis. Final Report

    Science.gov (United States)

    Nguyen, H. C.

    1984-01-01

    The microstructure, phase chemistry, and creep and hot tensile properties were studied as a function of tantalum and carbon levels in Mar-M247 type single crystal alloys. Microstructural studies showed that several types of carbides (MC, M23C6 and M5C) are present in the normal carbon (0.10 wt % C) alloys after heat treatment. In general, the composition of the MC carbides changes from titanium rich to tantalum rich as the tantalum level in the alloy increases. Small M23C6 carbides are present in all alloys. Tungsten rich M6C carbides are also observed in the alloy containing no tantalum. No carbides are present in the low carbon (0.01 wt % C) alloy series. The morphology of gamma prime is observed to be sensitive to heat treatment and tantalum level in the alloy. Cuboidal gamma prime is present in all the as cast structures. After heat treatment, the gamma prime precipitates tend to have a more spheroidal like morphology, and this tendency increases as the tantalum level decreases. On prolonged aging, the gamma prime reverts back to a cuboidal morphology or under stress at high temperatures, forms a rafted structure. The weight fraction and lattice parameter of the spheroidal gamma prime increases with increasing tantalum content. Changes in the phase chemistry of the gamma prime matrix and gamma prime have also been analyzed using phase extraction techniques. The partitioning ratio decreases for tungsten and aluminum and increases for tantalum as the tantalum content increases for both alloy series; no significant changes occur in the partitioning ratios of the other alloying elements. A reduction in secondary creep rate and an increase in rupture time result from increasing the tantalum content and decreasing the carbon level.

  12. New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

    Institute of Scientific and Technical Information of China (English)

    Homam Naff akh Moosavy; Mohammad-Reza Aboutalebi; Seyed Hossein Seyedein; Meisam Khodabakhshi; Carlo Mapelli

    2013-01-01

    A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern II, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing diff erent amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with diff erent corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

  13. New approach for assessing the weldability of precipitation-strengthened nickel-base superalloys

    Science.gov (United States)

    Moosavy, Homam Naffakh; Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein; Khodabakhshi, Meisam; Mapelli, Carlo

    2013-12-01

    A new procedure was proposed for evaluating the weldability of nickel-base superalloys. The theory is on the basis of two microstructural patterns. In pattern I, the weld microstructure exhibits severe alloying segregation, many low-melting eutectic structures, and low weldability. The weld requires a weaker etchant and a shorter time for etching. In pattern II, the weld microstructure displays less alloying segregation, low quantity of eutectic structures, and high weldability. The weld needs a stronger etchant and a longer time for etching. Five superalloys containing different amounts of Nb and Ti were designed to verify the patterns. After welding operations, the welds were etched by four etchants with different corrosivities. The weldability was determined by TG-DSC measurements. The metallography and weldability results confirmed the theoretic patterns. Finally, the etchant corrosivity and etching time were proposed as new criteria to evaluate the weldability of nickel-base superalloys.

  14. The Effect of Forging Variables on the Supersolvus Heat-Treatment Response of Powder-Metallurgy Nickel-Base Superalloys

    Science.gov (United States)

    2014-12-01

    AFRL-RX-WP-JA-2015-0160 THE EFFECT OF FORGING VARIABLES ON THE SUPERSOLVUS HEAT-TREATMENT RESPONSE OF POWDER-METALLURGY NICKEL -BASE SUPERALLOYS...POWDER-METALLURGY NICKEL - BASE SUPERALLOYS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62102F 6. AUTHOR...of Powder-Metallurgy Nickel -Base Superalloys S.L. SEMIATIN, J.M. SHANK, A.R. SHIVELEY, W.M. SAURBER, E.F. GAUSSA, and A.L. PILCHAK The effect of

  15. Use of atomic force microscopy to quantify slip irreversibility in a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M.; Feaugas, X.; Guillemer-Neel, C.; Clavel, M

    2003-09-15

    Atomic force microscopy was used to study the evolution of surface deformation during cyclic loading in a nickel-base superalloy. Cyclic slip irreversibility has been investigated using quantitative evaluation of extrusion heights and inter-band spacing. This approach is applied to formulate a microscopic crack initiation law, compared to a classical Manson-Coffin relationship.

  16. Directional coarsening in nickel-base superalloys and its effect on the mechanical properties

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    During high temperature loading, the regular microstructure of nickel-base superalloys consisting of a γ-matrix (Ni) containing a large volume fraction of γ′-particles (Ni3Al) degrades. The cubic precipitates coarsen and elongate in a direction normal to the applied stress in a process called raftin

  17. Micromechanical Behavior of Single-Crystal Superalloy with Different Crystal Orientations by Microindentation

    Directory of Open Access Journals (Sweden)

    Jinghui Li

    2015-01-01

    Full Text Available In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001, (215, (405, and (605, microindentation test (MIT was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardness H, Young’s modulus E, yield stress σy, strain hardening component n, and tensile strength σb, can be obtained from load-displacement relations. H and E of four different crystal planes evidently decrease with the increase of h. The reduction of H is due to dislocation hardening while E is related to interplanar spacing and crystal variable. σy of (215 is the largest among four crystal planes, followed by (605, and (001 has the lowest value. n of (215 is the lowest, followed by (605, and that of (001 is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.

  18. A Coupled Creep-Plasticity Model for Residual Stress Relaxation of a Shot-Peened Nickel-Base Superalloy

    Science.gov (United States)

    2007-05-01

    Superalloys for Turbine Discs ,” Journal of the Minerals, Metals & Materials Society (JOM), January 1999, pp. 14-17. 48. Fecht, H., and Furrer, D...Processing of Nickel-Base Superalloys for Turbine Engine Disc Applications,” Advanced Engineering Materials, Vol. 2, No. 12, 2000, pp. 777-787. 49...and McLean, M. “Tension-Compression creep asymmetry in a turbine disc superalloy : roles of internal stress and thermal ageing,” Acta Materialia, 52

  19. Quantitative evaluation of carbides in nickel-base superalloy MAR-M247

    Science.gov (United States)

    Szczotok, A.

    2011-05-01

    It has been established that carbides in superalloys serve three functions. Fine carbides precipitated in the matrix give strengthening results. Carbides also can tie up certain elements that would otherwise promote phase instability during service. Grain boundary carbides prevent or retard grain-boundary sliding and strengthen the grain boundary, which depends significantly on carbide shape, size and distribution. Various types of carbides are possible, depending on superalloy composition and processing. In the paper optical and scanning electron microscopy investigations of carbides occurring in specimens of the polycrystalline nickel-base superalloy MAR-M247 were carried out. Conditions of carbides revealing and microstructure images acquisition have been described. Taking into consideration distribution and morphology of the carbides in matrix a method of quantitative description of Chinese script-like and blocky primary carbides on the basis of image analysis was proposed.

  20. Interfacial dislocation motion and interactions in single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Raabe, D. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Roters, F. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Arsenlis, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  1. Effect of Grinding Temperatures on the Surface Integrity of a Nickel-based Superalloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An experimental study was carried out to investigat e the influence of temperatures on workpiece surface integrity in surface grinding of a cast nickel-based superalloy with alumina abrasive wheels. Temperatur e response at the wheel-workpiece interface was measured using a grindable foil /workpiece thermocouple. Specimens with different grinding temperatures were obt ained through changing grinding conditions including depth of cut, workpiece fee d speed, and coolant supply. Changes in surface roughnes...

  2. Calorimetric examination of mixtures for modification of nickel and cobalt superalloys

    OpenAIRE

    F. Binczyk; J. Sleziona; R. Przeliorz

    2009-01-01

    The study presents the results of thermodynamic calculations and calorimetric examination of thermal reactions taking place at hightemperatures between the nanoparticle inoculants and metallic constituents of nickel and cobalt superalloys. The calculations andmeasurements were made for different compositions, containing cobalt aluminate CoAl2O4, cobalt oxide CoO*Co2O3, zircon flourZrSi2O4, powdered and metallic Al, powdered Ti, and IN-713C alloy. The obtained results have indicated the possib...

  3. Microstructurally sensitive crack nucleation around inclusions in powder metallurgy nickel based superalloys

    OpenAIRE

    Jiang, J; Yang, J; Zhang, T.; J Zou; Wang,Y.,; Dunne, F.P.E.; Britton, T. B.

    2016-01-01

    ? 2016 Acta Materialia Inc.Nickel-based superalloys are used in high strength, high-value applications, such as gas turbine discs in aero engines. In these applications the integrity of the disc is critical and therefore understanding crack initiation mechanisms is of high importance. With an increasing trend towards powder metallurgy routes for discs, sometimes unwanted non-metallic inclusions are introduced during manufacture. These inclusions vary in size from ?10??m to 200??m which is com...

  4. Factors affecting the corrosion fatigue life in nickel based superalloys for disc applications

    OpenAIRE

    Rosier Hollie; Perkins Karen; Girling Andrew; Leggett Jonathan; Gibson Grant

    2014-01-01

    The nickel based superalloy 720Li is employed in the gas turbine due to its mechanical performance at elevated temperature. A comprehensive assessment of the materials behaviour under representative service conditions is reported to address the drive for ever increasing temperatures and more arduous environmental exposure. Fatigue experiments have been performed in an air and air/SOx environment at 700 ∘C containing a mixed salt as a contaminant. There is an intimate relationship between loca...

  5. Use of Precious Metal-Modifed Nickel-Base Superalloys for Thin Gage Applications (Preprint)

    Science.gov (United States)

    2011-04-01

    Historically, sandwich construction MTPS (outer surface-Alloy 617 nickel-base superalloy honeycomb core and face sheets; inner surface titanium alloy honeycomb ...National Aeronautics and Space Administration ( NASA ) X-33 vehicle2, a wedged-shaped subscale prototype of a reusable launch vehicle4 designed by...MTPS, materials under consideration must be very thin, 0.17 mm-0.25 mm for a typical face sheet and 0.05mm-0.10 mm for honeycomb core. One

  6. Development of the recovery technology for nickel superalloy blades of the aircraft engine by laser cladding

    Science.gov (United States)

    Bykovskiy, D. P.; Petrovskiy, V. N.; Polskiy, V. I.; Chirikov, S. N.; Dzhumaev, P. S.

    2016-09-01

    Development of cladding modes was performed with a superalloy nickel based powder on a flat substrate from material identical to compressor and turbine blades. Cross sections were made, and a visual inspection of the shape and the quality of the clad track as well as themetallographic analysis were performed. Microhardness of the deposition zone, chemical composition of the base, cladded metals, and the heat affected zone were determined.

  7. 镍基单晶高温合金在不同条件下的蠕变性能和组织演化%Creep properties and microstructure evolution of nickel-based single crystal superalloy at different conditions

    Institute of Scientific and Technical Information of China (English)

    史振学; 李嘉荣; 刘世忠; 王效光

    2014-01-01

    研究[001]取向的镍基单晶高温合金在不同测试条件下的蠕变性能,采用扫描电镜和透射电镜研究合金蠕变断裂后的γ′相、TCP相和位错组织演化特征。结果表明:合金具有良好的蠕变性能,蠕变曲线显示出两种不同的蠕变变形特征。在(760°C,600 MPa)、(850°C,550 MPa)条件下,蠕变第一阶段较长;在(980°C,250 MPa)、(1070°C,140 MPa)和(1100°C,120 MPa)条件下,蠕变第一阶段很短。蠕变断裂后,在(760°C,600 MPa)条件下γ′相形态变化不大;在(850°C,550 MPa)条件下γ′相已经合并长大;在(980°C,250 MPa)条件下基体γ被γ′相包围;在(1070°C,140 MPa)条件下基体γ不再连续;在(1100°C,120 MPa)条件下基体γ厚度进一步增加。在(760°C,600 MPa)、(850°C,550 MPa)和(980°C,250 MPa)条件下合金无TCP相析出,而在(1070°C,140 MPa)和(1100°C,120 MPa)条件下有针状TCP相析出。在低温高应力下,变形特征为位错包括层错的剪切机制;在高温低应力下为位错绕过机制,并在γ/γ′相界面形成位错网。%The creep properties of nickel-based single crystal superalloy with [001] orientation was investigated at different test conditions. The microstructure evolution of γ′ phase, TCP phase and dislocation characteristic after creep rupture was studied by SEM and TEM. The results show that the alloy has excellent creep properties. Two different types of creep behavior can be shown in the creep curves. The primary creep is characterized by the high amplitude at test conditions of (760 °C, 600 MPa) and (850 °C, 550 MPa) and the primary creep strain is limited at (980 °C, 250 MPa), (1100 °C, 140 MPa) and (1120 °C, 120 MPa). A little change ofγ′precipitate morphology occurs at (760 °C, 600 MPa). The lateral merging of the γ′ precipitate has already begun at (850 °C, 550 MPa). Theγphase is surrounded by theγ′phase at (980 °C, 250 MPa). Theγphase is no longer

  8. Effect of solidification rate on competitive grain growth in directional solidification of a nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU YiZhou; SUN XiaoFeng

    2012-01-01

    The mechanism of grain structure evolution during directional solidification is a fundamental subject in material science.Within the published research there exist conflicting views on the mechanism of grain overgrowth.To study the effect of solidification rate on grain structure evolution,bi-crystals samples were produced in a nickel-base superalloy at different solidification rates.It was found that at the convergent grain boundaries those grains better aligned with respect to the heat flux more readily overgrew neighbouring grains with misaligned orientations and the effect became more pronounced as solidification rate was increased.However,at diverging grain boundaries the rate of overgrowth was invariant to the solidification rate.These experimental results were compared with models in the literature.Thus,a better insight into competitive grain growth in directional solidification processes was obtained.

  9. Thermophysical and structural study of IN 792-5A nickel based superalloy

    Directory of Open Access Journals (Sweden)

    S. Zlá

    2012-01-01

    Full Text Available The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C•min-1 and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733 equipped with energy dispersive analyser EDAX (EDAM 3.

  10. Fabrication of directional solidification components of nickel-base superalloys by laser metal forming

    Institute of Scientific and Technical Information of China (English)

    Liping Feng; Weidong Huang; Darong Chen; Xin Lin; Haiou Yang

    2004-01-01

    Straight plates, hollow columns, ear-like blade tips, twist plates with directional solidification microstructure made of Rene 95 superalloys were successfully fabricated on Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for production of the parts with corresponding shapes were obtained. The fabrication precision was high and the components were compact. The solidification microstructure of the parts was analyzed by optical microscopy. The results show that the solidification microstructure is composed of columnar dendrites, by epitaxial growth onto the directional solidification substrates. The crystallography orientation of the parts was parallel to that of the substrates. The primary arm spacing was about 10 μm, which is in the range of superfine dendrites, and the secondary arm was small or even degenerated. It is concluded that the laser metal forming technique provides a method to manufacture directional solidification components.

  11. Microstructure of the Nickel-Base Superalloy CMSX-4 Fabricated by Selective Electron Beam Melting

    Science.gov (United States)

    Ramsperger, Markus; Singer, Robert F.; Körner, Carolin

    2016-03-01

    Powder bed-based additive manufacturing (AM) processes are characterized by very high-temperature gradients and solidification rates. These conditions lead to microstructures orders of magnitude smaller than in conventional casting processes. Especially in the field of high performance alloys, like nickel-base superalloys, this opens new opportunities for homogenization and alloy development. Nevertheless, the high susceptibility to cracking of precipitation-hardenable superalloys is a challenge for AM. In this study, electron beam-based AM is used to fabricate samples from gas-atomized pre-alloyed CMSX-4 powder. The influence of the processing strategy on crack formation is investigated. The samples are characterized by optical and SEM microscopy and analyzed by microprobe analysis. Differential scanning calorimetry is used to demonstrate the effect of the fine microstructure on characteristic temperatures. In addition, in situ heat treatment effects are investigated.

  12. Yielding and deformation behavior of the single crystal superalloy PWA 1480

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1987-01-01

    Interrupted tensile tests were conducted to fixed plastic strain levels in 100 ordered single crystals of the nickel based superalloy PWA 1480. Testing was done in the range of 20 to 1093 C, at strain rate of 0.5 and 50 percent/min. The yield strength was constant from 20 to 760 C, above which the strength dropped rapidly and became a strong function of strain rate. The high temperature data were represented very well by an Arrhenius type equation, which resulted in three distinct temperature regimes. The deformation substructures were grouped in the same three regimes, indicating that there was a fundamental relationship between the deformation mechanisms and activation energies. Models of the yielding process were considered, and it was found that no currently available model was fully applicable to this alloy. It was also demonstrated that the initial deformation mechanism (during yielding) was frequently different from that which would be inferred by examining specimens which were tested to failure.

  13. First principles calculations of the site substitution behavior in gamma prime phase in nickel based superalloys

    Science.gov (United States)

    Chaudhari, Mrunalkumar

    Nickel based superalloys have superior high temperature mechanical strength, corrosion and creep resistance in harsh environments and found applications in the hot sections as turbine blades and turbine discs in jet engines and gas generator turbines in the aerospace and energy industries. The efficiency of these turbine engines depends on the turbine inlet temperature, which is determined by the high temperature strength and behavior of these superalloys. The microstructure of nickel based superalloys usually contains coherently precipitated gamma prime (gamma') Ni3Al phase within the random solid solution of the gamma (gamma) matrix, with the gamma' phase being the strengthening phase of the superalloys. How the alloying elements partition into the gamma and gamma' phases and especially in the site occupancy behaviors in the strengthening gamma' phases play a critical role in their high temperature mechanical behaviors. The goal of this dissertation is to study the site substitution behavior of the major alloying elements including Cr, Co and Ti through first principles based calculations. Site substitution energies have been calculated using the anti-site formation, the standard defect formation formalism, and the vacancy formation based formalism. Elements such as Cr and Ti were found to show strong preference for Al sublattice, whereas Co was found to have a compositionally dependent site preference. In addition, the interaction energies between Cr-Cr, Co-Co, Ti-Ti and Cr-Co atoms have also been determined. Along with the charge transfer, chemical bonding and alloy chemistry associated with the substitutions has been investigated by examining the charge density distributions and electronic density of states to explain the chemical nature of the site substitution. Results show that Cr and Co atoms prefer to be close by on either Al sublattice or on a Ni-Al mixed lattice, suggesting a potential tendency of Cr and Co segregation in the gamma' phase.

  14. Characterization of fatigue mechanisms in nickel-based superalloys

    Science.gov (United States)

    Yablinsky, Clarissa A.

    Ni-based superalloys are important for turbine engine airfoil applications. Historically, creep has been the main failure mode and thus creep mechanisms have been the subject of numerous studies. However, modern airfoil designs maintain cooler temperatures, and consequently creep is no longer the primary failure mode. Rather, in the cooled components, experience and experimental studies have shown that fatigue is the life-limiting factor. The changing cause of failure highlighted the need for a comprehensive study of fatigue deformation mechanisms. Information about crack propagation and the associated deformation mechanisms has allowed appropriate design changes based on fatigue as a life-limiting factor. The focus of the study will be on a monocrystalline Ni-based superalloy, Rene N5, which is currently used for airfoils. Compact tension specimens were tested under cyclic loading conditions to determine the influence of microstructure and material properties on crack propagation and fatigue failure. The crack growth rate as a function of temperature, environment, frequency, and crystallographic orientation was determined. High resolution scanning electron microscopy was used to examine the fracture surface on length scales from nano to macro. Deformation mechanisms in the plastic zone ahead of the crack tip and within the plastic wake of the crack were studied using TEM and FIB techniques. Environment and frequency seem to have a larger effect on fatigue crack growth rates and threshold stress intensity factor ranges, while temperature and orientation effects are present, but not as dramatic. In the normal blade orientation, (001)[100], mode I crack propagation was prevalent, with mode II crack propagation found at higher DeltaK values. Interdendritic particles appear to be slowing crack growth rates in the threshold region of specimens tested in air. Microstructural analysis showed no change in gamma' precipitate size or morphology with temperature or stress

  15. Comparison of measured and calculated thermophysical properties of nickel super-alloys

    Directory of Open Access Journals (Sweden)

    A. Kalup

    2016-07-01

    Full Text Available Three real grades of nickel super-alloys (IN 713LC, IN 738LC and IN 792-5A were investigated and values of temperatures of phase transformations and latent heats of melting were obtained. All investigated quantities are very important for thermodynamic and kinetic modelling. Moreover, these data are also valuable for a lot of software used for technological processes modelling. Experimental values were obtained using Differential Thermal Analysis (DTA measurements. Calculations were performed using Thermo-Calc 3.1 software with the use of three different databases (SSOL5, TTNI8 and TCNI6. Comparison and discussion of experimental and calculated data was performed.

  16. Nucleation mechanism of a nickel-base superalloy during dynamic recrystallization

    Institute of Scientific and Technical Information of China (English)

    Shuai WANG; Lei WANG; Yang LIU; Guohua XU; Beijiang ZHANG; Guangpu ZHAO

    2011-01-01

    Hot compression test was carried out at 1000 ℃ to investigate the dynamic recrystallization nucleation mechanism of a nickel-base superalloy.It was found that the bulging of original grain boundaries was inhibited by carbides and deformation twins at the boundaries.Recrystallized nuclei evolved from the subgrains of dislocation reconfiguration along original grain boundaries,and the growth of the potential nuclei was carried out by the coalescence of subgrains.The necklace structure of recrystallized grains along original grain boundaries was attributed to the strain gradient from grain boundary to grain interior.

  17. Analysis of the solidified structure of rheocast and VADER processed nickel-base superalloy

    Science.gov (United States)

    Apelian, D.; Cheng, J.-J. A.

    1986-01-01

    Conventional 'ingot' processing of highly alloyed compositions results in a cast product which suffers from extensive macrosegregation, hot tears, and heterogeneities. By controlling the solidification journey, one can produce a fine grained cast product. This is achieved by manipulating the melt in the mushy zone. Rheocasting and vacuum arc double electrode remelting (VADER) are two such technologies where the melt is processed in the mushy zone. IN-100, a nickel based superalloy, was rheocast as well as VADER processed. The resultant cast structures are analyzed, compared and discussed both onmicro- and macrostructural levels. The effect of the rheocast processing variables (stirring seed, time and temperature) on the cast microstructure are also discussed.

  18. Precipitation in Powder Metallurgy, Nickel Base Superalloys: Review of Modeling Approach and Formulation of Engineering (Postprint)

    Science.gov (United States)

    2016-12-01

    such as those of interest here, the work of Campbell et al. [60] and Semiatin et al. [50] suggests that Cr diffusion is rate limiting in γ-γ...the work of Campbell et al. [60]. In addition, w(f ) was taken from the research of Voorhees and Glicksman [20], and σ was assumed to be 23 mJ/m2 per...2104) Alloying-element loss during high-temperature processing of a nickel-base superalloy. Metall Mater Trans A 45:962–979 60. Campbell CE, Zhao JC

  19. Metallurgical instabilities during the high temperature low cycle fatigue of nickel-base superalloys

    Science.gov (United States)

    Antolovich, S. D.; Jayaraman, N.

    1983-01-01

    An investigation is made of the microstructural instabilities that affect the high temperature low cycle fatigue (LCF) life of nickel-base superalloys. Crack initiation processes, provoked by the formation of carbides and the coarsening of the grains of the material at high temperatures are discussed. Experimental results are examined, and it is concluded that LCF behavior can be understood more fully only if details of the material and its dynamic behavior at high temperatures are considered. The effects of high stress, dislocation debris, and increasing environmental damage on the life of the alloy are discussed.

  20. Homogenization kinetics of a nickel-based superalloy produced by powder bed fusion laser sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan; Levine, Lyle E.; Allen, Andrew J.; Campbell, Carelyn E.; Lass, Eric A.; Cheruvathur, Sudha; Stoudt, Mark R.; Williams, Maureen E.; Idell, Yaakov

    2017-04-01

    Additively manufactured (AM) metal components often exhibit fine dendritic microstructures and elemental segregation due to the initial rapid solidification and subsequent melting and cooling during the build process, which without homogenization would adversely affect materials performance. In this letter, we report in situ observation of the homogenization kinetics of an AM nickel-based superalloy using synchrotron small angle X-ray scattering. The identified kinetic time scale is in good agreement with thermodynamic diffusion simulation predictions using microstructural dimensions acquired by ex situ scanning electron microscopy. These findings could serve as a recipe for predicting, observing, and validating homogenization treatments in AM materials.

  1. Study of Flow Softening Mechanisms of a Nickel-Based Superalloy With Δ Phase

    Directory of Open Access Journals (Sweden)

    Lin Y.C.

    2016-09-01

    Full Text Available The flow softening behaviors of a nickel-based superalloy with δ phase are investigated by hot compression tests over wide ranges of deformation temperature and strain rate. Electron backscattered diffraction (EBSD, optical microscopy (OM, and scanning electron microscopy (SEM are employed to study the flow softening mechanisms of the studied superalloy. It is found that the flow softening behaviors of the studied superalloy are sensitive to deformation temperature and strain rate. At high strain rate and low deformation temperature, the obvious flow softening behaviors occur. With the increase of deformation temperature or decrease of strain rate, the flow softening degree becomes weaken. At high strain rate (1s−1, the flow softening is mostly induced by the plastic deformation heating and flow localization. However, at low strain rate domains (0.001-0.01s−1, the effects of deformation heating on flow softening are slight. Moreover, the flow softening at low strain rates is mainly induced by the discontinuous dynamic recrystallization and the dissolution of δ phase (Ni3Nb.

  2. Welding Metallurgy of Nickel-Based Superalloys for Power Plant Construction

    Science.gov (United States)

    Tung, David C.

    Increasing the steam temperature and pressure in coal-fired power plants is a perpetual goal driven by the pursuit of increasing thermal cycle efficiency and reducing fuel consumption and emissions. The next target steam operating conditions, which are 760°C (1400°F) and 35 MPa (5000 psi) are known as Advanced Ultra Supercritical (AUSC), and can reduce CO2 emissions up to 13% but this cannot be achieved with traditional power plant construction materials. The use of precipitation-strengthened Nickel-based alloys (superalloys) is required for components which will experience the highest operating temperatures. The leading candidate superalloys for power plant construction are alloys 740H, 282, and 617. Superalloys have excellent elevated temperature properties due to careful microstructural design which is achieved through very specific heat treatments, often requiring solution annealing or homogenization at temperatures of 1100 °C or higher. A series of postweld heat treatments was investigated and it was found that homogenization steps before aging had no noticeable effect on weld metal microhardness, however; there were clear improvements in weld metal homogeneity. The full abstract can be viewed in the document itself.

  3. Investigation of Creep Feed Grinding Parameters and Heat treatment Effects on the Nickel-base Superalloys

    Institute of Scientific and Technical Information of China (English)

    Hasan Jamshidi; Sayed Ali Sadough Vanini; Alireza Attari

    2004-01-01

    The Nickel base Superalloys are the most famous complicated and useable of Superalloys to make hot zone components of the gas turbines. The complicated dimensional tolerances, specially at the root of the blade show importance of grinding processes at the production of blades root. The prediction of the effect of machining parameters on the soundness of component surface strengthening for reaching to a suitable surface finishing and avoiding from crack formation at the work part during machining operation often is not easy and feasible so needs to more industrial investigation.This research is about frame 5 blade designed by GE and made from Superalloy IN738LC has been investigated. The formation of a plastically deformed and heat affected zone during grinding of Superalloy IN738LC with a high depth of cut but slow work speed (creep feed grinding) was investigated. Parameters such as work speed, depth of cut and radial dressing speed have been considered as variables and their effects have been studied. During experimental performed, the voltage and current of motor measured and power and special energy calculated.Some samples heat-treated (of the 1176℃ for 1 hr under neutral argon gas and cooling rate of 15℃/min up to 537℃ and then air cooling) to study grains recrystallization. Other samples have been created from the roots of blades and then coated by Nickel to measure boundary layer micro-hardness. The results show that increasing work speed leads to increasing the use power. Increasing the depth of cut, by increasing material removal rate, and the radial dressing speed, by decreasing power, lead to decreasing special energy. The temperature created by grinding lead to decreasing plastic deformation and boundary layer formation. When the radial dressing speed changes from 1 to 0.6 μm/rev and other parameters are kept unchanged the roughness of surface increases and the special energy decreases. Sufficient dressing is very essential in limiting the width

  4. Influence of Ta content on hot corrosion behaviour of a directionally solidified nickel base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, F.F. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Chang, J.X., E-mail: jxchang11s@imr.ac.cn [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li, H.; Lou, L.H. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Zhang, J. [Superalloy Division, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2015-01-15

    Highlights: • Three nickel-base superalloys containing different Ta content were subjected to Na{sub 2}SO{sub 4}-induced hot corrosion. • Ta improved the hot corrosion resistance. • Ta decreased the diffusion rate of alloying elements. • Ta promoted the formation of (Cr, Ti)TaO{sub 4} layer. - Abstract: Hot corrosion behaviour of a directionally solidified nickel base superalloy with different tantalum (Ta) addition in fused sodium sulphate (Na{sub 2}SO{sub 4}) under an oxidizing atmosphere at 900 °C has been studied. It was shown that the hot corrosion resistance was improved by increasing of Ta content. The hot corrosion kinetics of the alloy with lower Ta content deviated from parabolic law after 60 h corrosion test, whereas the corrosion kinetics of the alloy with high Ta content followed the parabolic law before 60 h and with less mass change afterwards. A detailed microstructure study using scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD) was performed to investigate the corrosion products and mechanisms. The beneficial effect of Ta was found to be resulted from a Ta-enriched (Cr, Ti)TaO{sub 4} layer inside the corrosion scale, which led to the retarding of the element diffusion so as to decrease the hot corrosion kinetics.

  5. An experimental study on quasi-CW fibre laser drilling of nickel superalloy

    Science.gov (United States)

    Marimuthu, S.; Antar, M.; Dunleavey, J.; Chantzis, D.; Darlington, W.; Hayward, P.

    2017-09-01

    Laser drilling of metals and alloys is extensively used in modern manufacturing industries to produce holes of various size and shape. Currently, most laser drilling of aerospace nickel superalloys is performed using Nd:YAG laser. Over the years, many attempts were made to increase the productivity of Nd:YAG lasers drilling process, but with little success. This paper investigates the fundamental aspects of millisecond-pulsed-Quasi-CW-fibre laser drilling of aerospace nickel superalloy. The main investigation concentrates on understanding the Quasi-CW-fibre laser parameters on trepanning laser drilled hole quality and speed. The principal findings are based on controlling the recast layer, oxide layer, hole surface characteristic and fatigue performance of the laser drilled samples. The results showed that the high average power of the quasi-CW-fibre lasers can be effectively used to achieve increased trepanning drilling speed without undermining the drilling quality, which is not feasible with a free-space Nd:YAG laser. Also, low peak power and high frequency (of quasi-CW-fibre laser) can be effectively used to produce better laser drilled holes than the high peak power and low frequency, which is common with the traditional millisecond Nd:YAG drilling processes. Recast layer thickness of around 30 μm can be achieved with a trepanning speed of up to 500 mm/min with single orbit Quasi-CW fibre laser drilling of 0.75 mm hole over 5 mm thick material.

  6. Technology of laser repair welding of nickel superalloy inner flaps of jet engine

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2011-07-01

    Full Text Available Purpose: of this paper: work out laser welding repair technology of cracked MIG 29 jet engine inner flaps made of cast nickel superalloy ŻS-3DK (ЖС-3ДК, Russian designation.Design/methodology/approach: The study were based on the analysis of laser HPDL powder INCONEL 625 welding of nickel superalloy using wide range of welding parameters to provide highest quality repair welds.Findings: Study of automatic welding technologies GTA, PTA and laser HPDL has shown that just laser welding can provide high quality repair welds. In order to establish the properties of welded joints repair cracks in the inner flap HPDL laser, studied the hardness, mechanical properties and erosive wear resistance.Research limitations/implications: It was found that only laser HPDL welding can provide high quality repair welds.Practical implications: The technology can be applied for repair cracked MIG 29 jet engine inner flaps.Originality/value: Repairing cracked MIG 29 jet engine inner flaps.

  7. Effect of Heat Treatment Process on Microstructure and Fatigue Behavior of a Nickel-Base Superalloy

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2015-09-01

    Full Text Available The study of fatigue behaviors for nickel-base superalloys is very significant because fatigue damage results in serious consequences. In this paper, two kinds of heat treatment procedures (Pro.I and Pro.II were taken to investigate the effect of heat treatment on microstructures and fatigue behaviors of a nickel-base superalloy. Fatigue behaviors were studied through total strain controlled mode at 650 °C. Manson-Coffin relationship and three-parameter power function were used to predict fatigue life. A good link between the cyclic/fatigue behavior and microscopic studies was established. The cyclic deformation mechanism and fatigue mechanism were discussed. The results show that the fatigue resistance significantly drops with the increase of total strain amplitudes. Manson-Coffin relationship can well predict the fatigue life for total strain amplitude from 0.5% to 0.8%. The fatigue resistance is related with heat treatment procedures. The fatigue resistance performance of Pro.I is better than that of Pro.II. The cyclic stress response behaviors are closely related to the changes of the strain amplitudes. The peak stress of the alloy gradually increases with the increase of total strain amplitudes. The main fracture mechanism is inhomogeneous deformation and the different interactions between dislocations and γ′ precipitates.

  8. A Method of Stray Grain Suppression for Single-Crystal Superalloy During Seed Melt-Back

    Science.gov (United States)

    Xuan, Weidong; Lan, Jian; Liu, Huan; Li, Chuanjun; Zhong, Yunbo; Ren, Xingfu; Li, Xi; Cao, Guanghui; Ren, Zhongming

    2016-12-01

    The suppression of stray grains during seed melt-back of single-crystal superalloy through thermal resistance technique has been investigated based on both experimental observations and numerical simulation. The results indicate that the introduction of thermal resistance layer significantly suppresses the stray grain formation of single-crystal superalloy. Based on both theoretical analysis and numerical simulation, above results should be attributed to the decrease of radial heat transfer of sample in the thermal resistance layer.

  9. Mechanical properties of nanostructured nickel based superalloy Inconel 718

    Science.gov (United States)

    Mukhtarov, Sh; Ermachenko, A.

    2010-07-01

    This paper will describe the investigations of a nanostructured (NS) state of nickel based INCONEL® alloy 718. This structure was generated in bulk semiproducts by severe plastic deformation (SPD) via multiple isothermal forging (MIF) of a coarse-grained alloy. The initial structure consisted of γ-phase grains with disperse precipitations of γ"-phase in the forms of discs, 50-75 nm in diameter and 20 nm in thickness. The MIF generated structures possess a large quantity of non-coherent plates and rounded precipitations of δ-phase, primarily along grain boundaries. In the duplex (γ+δ) structure the grains have high dislocation density and a large number of nonequilibrium boundaries. Investigations to determine mechanical properties of the alloy in a nanostructured state were carried out. Nanocrystalline Inconel 718 (80 nm) possesses a very high room-temperature strength after SPD. Microcrystalline (MC) and NS states of the alloy were subjected to strengthening thermal treatment, and the obtained results were compared in order to determine their mechanical properties at room and elevated temperatures.

  10. Mechanical properties of white layers formed by different machining processes on nickel-based superalloy

    Science.gov (United States)

    Proust, Edouard

    Nickel-based superalloys are widely used in the aerospace industry in the production of turbine discs and blades because of their good mechanical properties and great corrosion resistance at high temperature. Although very useful, these alloys are hard to machine. Their structure is responsible for rapid wear of cutting tools. Moreover, under certain machining conditions, near-surface regions of the material undergo a phase transformation resulting in the formation of a thin layer called "white etching layer" at the surface of the machined workpiece. Because turbine discs are safety critical components, no defects can be tolerated on the workpiece. Therefore, efforts should be made to ensure that this white etching layer can't influence the operating life of the workpiece and make its operation unsafe. Even if the existence of the white etching layer is well known, its mechanical properties have never been assessed in detail. In this thesis, we present a study of the mechanical (hardness and Young's modulus) and microstructural properties of white etching layers formed at the surface of nickel-based superalloy IN100 turbine discs fabricated by different machining processes. This work aims at evaluating the impact of the machining process and of fatigue on the properties of the white etching layers under study. The originality of this study primarily lies in the employed characterization technique. Using nanoindentation has allowed us to very precisely assess the variations of both the hardness and the Young's modulus along the white etching layers. Also, the use of a sophisticated indentation system has enabled the acquisition of very precise surface images of the samples and therefore to study the microstructure of the white etching layers. This research has demonstrated that the mechanical and microstructural properties of the white etching layers are closely linked to the machining conditions of the material. Therefore, our study will help researchers gain a

  11. Solution and Aging of MAR-M246 Nickel-Based Superalloy

    Science.gov (United States)

    Baldan, Renato; da Silva, Antonio Augusto Araújo Pinto; Nunes, Carlos Angelo; Couto, Antonio Augusto; Gabriel, Sinara Borborema; Alkmin, Luciano Braga

    2017-02-01

    Solution and aging heat-treatments play a key role for the application of the superalloys. The aim of this work is to evaluate the microstructure of the MAR-M246 nickel-based superalloy solutioned at 1200 and 1250 °C for 330 min and aged at 780, 880 and 980 °C for 5, 20 and 80 h. The γ' solvus, solidus and liquidus temperatures were calculated with the aid of the JMatPro software (Ni database). The as-cast and heat-treated samples were characterized by SEM/EDS and SEM-FEG. The γ' size precipitated in the aged samples was measured and compared with JMatPro simulations. The results have shown that the sample solutioned at 1250 °C for 330 min showed a very homogeneous γ matrix with carbides and cubic γ' precipitates uniformly distributed. The mean γ' size of aged samples at 780 and 880 °C for 5, 20 and 80 h did not present significant differences when compared to the solutioned sample. However, a significant increasing in the γ' particles was observed at 980 °C, evidenced by the large mean size of these particles after 80 h of aging heat-treatment.

  12. Optimality analysis of multiplex A-TIG welding flux for nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    Fan Chenglei; Yang Chunli; Liang Yingchun; Lin Sanbao; Yu Xiang

    2007-01-01

    Orthogonal experiment is employed to study a new kind of multiplex flux for nickel-base superalloy. This activated TIG welding flux is composed of NaF, MgF2 and CaF2, and their proportion is 5:4:1. Compared with conventional TIG welding, the penetration increases 164% by the action of the flux. Tensile test result indicates that the fracture strength of the mixed flux A-TIG weld bead is higher than base metal, and it increases along with the decrement of the welding current. The average extensibility of the weldment is beyond 100%, which means perfect ductility. Metallographs elucidate that there exist lots of deep and evenly distributed dimples on the fracture section of weld bead while on that of base metal there only exists a few shallow dimples and massive tearing ridge.

  13. Evaluation of Heat Capacity and Resistance to Cyclic Oxidation of Nickel Superalloys

    Directory of Open Access Journals (Sweden)

    Przeliorz R.

    2014-08-01

    Full Text Available Paper presents the results of evaluation of heat resistance and specific heat capacity of MAR-M-200, MAR-M-247 and Rene 80 nickel superalloys. Heat resistance was evaluated using cyclic method. Every cycle included heating in 1100°C for 23 hours and cooling for 1 hour in air. Microstructure of the scale was observed using electron microscope. Specific heat capacity was measured using DSC calorimeter. It was found that under conditions of cyclically changing temperature alloy MAR-M-247 exhibits highest heat resistance. Formed oxide scale is heterophasic mixture of alloying elements, under which an internal oxidation zone was present. MAR-M-200 alloy has higher specific heat capacity compared to MAR-M-247. For tested alloys in the temperature range from 550°C to 800°C precipitation processes (γ′, γ″ are probably occurring, resulting in a sudden increase in the observed heat capacity.

  14. Hot corrosion behavior of the spray-formed nickel-based superalloy

    Science.gov (United States)

    Xia, Min; Gu, Tian-Fu; Jia, Chong-Lin; Ge, Chang-Chun

    2016-12-01

    An investigation of low temperature hot corrosion is carried out on a spray-formed nickel-based superalloy FGH100 pre-coated with Na2SO4-NaCl at 700 °C for 100 h. Mass gain measurement, x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy are used to study the corrosion behavior. Results reveal that corrosion behavior follows a sequence, that is, first rapidly proceeding, then gradually slowing down, and finally forming an outer layer composed of different types of oxides and an inner layer mainly comprised of sulfides. In-depth analysis reveals that the hot corrosion of FGH100 is a combined effect of oxidation-sulfidation and transfer of oxides.

  15. The effects of thermomechanical history on the microstructure of a nickel-base superalloy during forging

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, S., E-mail: 485354@swansea.ac.uk [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom); Li, W. [Rolls-Royce plc, PO Box 31, Derby DE24 8BJ (United Kingdom); Coleman, M. [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom); Johnston, R., E-mail: r.johnston@swansea.ac.uk [College of Engineering, Bay Campus, Swansea University, Swansea SA1 8EN (United Kingdom)

    2016-06-21

    The effect of thermo-mechanical history on hot compression behaviour and resulting microstructures of a nickel base superalloy is presented. Hot compression tests were carried out on HAYNES® 282® specimens to varying strains from 0.1 to 0.8. Both single pass and multi-pass tests were completed. 60 min inter-pass times were utilized to accurately replicate industrial forging practices. The effect of dynamic, metadynamic and static recrystallization during inter-pass times on flow stress was investigated. The resulting microstructures were analysed using scanning electron, optical microscopy and EBSD to relate grain size and homogeneity with flow stress data. The study showed a negligible difference between multi-pass and single pass tests for strain increments above 0.2. Therefore, when modelling similar low strain and strain rate forging processes in HAYNES® 282®, previous forging steps can be ignored.

  16. Recent Advances in Creep Modelling of the Nickel Base Superalloy, Alloy 720Li

    Directory of Open Access Journals (Sweden)

    Steve Williams

    2013-03-01

    Full Text Available Recent work in the creep field has indicated that the traditional methodologies involving power law equations are not sufficient to describe wide ranging creep behaviour. More recent approaches such as the Wilshire equations however, have shown promise in a wide range of materials, particularly in extrapolation of short term results to long term predictions. In the aerospace industry however, long term creep behaviour is not critical and more focus is required on the prediction of times to specific creep strains. The current paper illustrates the capability of the Wilshire equations to recreate full creep curves in a modern nickel superalloy. Furthermore, a finite-element model based on this method has been shown to accurately predict stress relaxation behaviour allowing more accurate component lifing.

  17. Factors affecting the corrosion fatigue life in nickel based superalloys for disc applications

    Directory of Open Access Journals (Sweden)

    Rosier Hollie

    2014-01-01

    Full Text Available The nickel based superalloy 720Li is employed in the gas turbine due to its mechanical performance at elevated temperature. A comprehensive assessment of the materials behaviour under representative service conditions is reported to address the drive for ever increasing temperatures and more arduous environmental exposure. Fatigue experiments have been performed in an air and air/SOx environment at 700 ∘C containing a mixed salt as a contaminant. There is an intimate relationship between local salt level (flux, stress level and stress state, i.e. static or cyclic. The interaction with these variables with the work hardened layer present on the surface of all tested specimens as a result of the shot peening process directly affects the crack initiation process. If specific conditions of environment and stress are achieved, a significant reduction in fatigue life is observed.

  18. Development of a Nickel-base Cast Superalloy with High Strength and Superior Creep Properties

    Institute of Scientific and Technical Information of China (English)

    Jieshan HOU; Jianting GUO; Lanzhang ZHOU; Zhijun LI

    2005-01-01

    Derived from Russian alloy CHS88U, six experimental Ni-base alloys named as A to F in the Ni-Cr-Co-W-Ti-Al-Hf system are designed, evaluated and processed. One of these alloys, F, shows excellent high temperature tensile strength and ductility with superior creep rupture properties. As predicted by using modeling tools such as PHACOM and NEW PHACOMP, there is hardly the tendency for formation of topologically close-packed phase (TCP) phase in alloy F. Furthermore, through microstructural observation, it is also found that no TCP phase is formed in alloy F after long-time exposure at high temperature. So alloy F has well balance of phase stability and mechanical properties in view of application for gas turbines. It is proved that d-electron approach can be applied for design and development of nickel-base superalloys for gas turbine application.

  19. High-Temperature Oxidation Behavior of Two Nickel-Based Superalloys Produced by Metal Injection Molding for Aero Engine Applications

    Science.gov (United States)

    Albert, Benedikt; Völkl, Rainer; Glatzel, Uwe

    2014-09-01

    For different high-temperature applications like aero engines or turbochargers, metal injection molding (MIM) of superalloys is an interesting processing alternative. For operation at high temperatures, oxidation behavior of superalloys produced by MIM needs to match the standard of cast or forged material. The oxidation behavior of nickel-based superalloys Inconel 713 and MAR-M247 in the temperature interval from 1073 K to 1373 K (800 °C to 1100 °C) is investigated and compared to cast material. Weight gain is measured discontinuously at different oxidation temperatures and times. Analysis of oxidized samples is done via SEM and EDX-measurements. MIM samples exhibit homogeneous oxide layers with a thickness up to 4 µm. After processing by MIM, Inconel 713 exhibits lower weight gain and thinner oxide layers than MAR-M247.

  20. Hot corrosion resistance of high-velocity oxyfuel sprayed coatings on a nickel-base superalloy in molten salt environment

    Science.gov (United States)

    Sidhu, T. S.; Prakash, S.; Agrawal, R. D.

    2006-09-01

    No alloy is immune to hot corrosion attack indefinitely. Coatings can extend the lives of substrate materials used at higher temperatures in corrosive environments by forming protective oxides layers that are reasonably effective for long-term applications. This article is concerned with studying the performance of high-velocity oxyfuel (HVOF) sprayed NiCrBSi, Cr3C2-NiCr, Ni-20Cr, and Stellite-6 coatings on a nickel-base superalloy at 900 °C in the molten salt (Na2SO4-60% V2O5) environment under cyclic oxidation conditions. The thermogravimetric technique was used to establish kinetics of corrosion. Optical microscope, x-ray diffraction, scanning electron microscopy/electron dispersive analysis by x-ray (SEM/EDAX), and electron probe microanalysis (EPMA) techniques were used to characterize the as-sprayed coatings and corrosion products. The bare superalloy suffered somewhat accelerated corrosion in the given environmental conditions. whereas hot corrosion resistance of all the coated superalloys was found to be better. Among the coating studied, Ni-20Cr coated superalloy imparted maximum hot corrosion resistance, whereas Stellite-6 coated indicated minimum resistance. The hot corrosion resistance of all the coatings may be attributed to the formation of oxides and spinels of nickel, chromium, or cobalt.

  1. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [GE Global Research, NIskayuna, NY (United States); Gupta, Vipul [GE Global Research, NIskayuna, NY (United States); Huang, Shenyan [GE Global Research, NIskayuna, NY (United States); Soare, Monica [GE Global Research, NIskayuna, NY (United States); Zhao, Pengyang [GE Global Research, NIskayuna, NY (United States); Wang, Yunzhi [GE Global Research, NIskayuna, NY (United States)

    2017-02-28

    The goal of this project is to model long-term creep performance for nickel-base superalloy weldments in high temperature power generation systems. The project uses physics-based modeling methodologies and algorithms for predicting alloy properties in heterogeneous material structures. The modeling methodology will be demonstrated on a gas turbine combustor liner weldment of Haynes 282 precipitate-strengthened nickel-base superalloy. The major developments are: (1) microstructure-property relationships under creep conditions and microstructure characterization (2) modeling inhomogeneous microstructure in superalloy weld (3) modeling mesoscale plastic deformation in superalloy weld and (4) a constitutive creep model that accounts for weld and base metal microstructure and their long term evolution. The developed modeling technology is aimed to provide a more efficient and accurate assessment of a material’s long-term performance compared with current testing and extrapolation methods. This modeling technology will also accelerate development and qualification of new materials in advanced power generation systems. This document is a final technical report for the project, covering efforts conducted from October 2014 to December 2016.

  2. What is the role of rhenium in single crystal superalloys?

    Directory of Open Access Journals (Sweden)

    Mottura Alessandro

    2014-01-01

    Full Text Available Rhenium plays a critical role in single-crystal superalloys –its addition to first generation alloys improves creep life by a factor of at least two, with further benefits for fatigue performance. Its use in alloys such as PWA1484, CMSX-4 and Rene N5 is now widespread, and many in this community regard Re as the “magic dust”. In this paper, the latest thinking concerning the origins of the “rhenium-effect” is presented. We start by reviewing the hypothesis that rhenium clusters represent barriers to dislocation motion. Recent atom probe tomography experiments have shown that Re may instead form a solid solution with Ni at low concentrations (< 7 at.%. Density functional theory calculations indicate that, in the solid solution, short range ordering of Re may be expected. Finally, Re has been shown to diffuse slowly in the γ-Ni phase. Calculations using a semi-analytical dislocation climb/glide model based upon the work of McLean and Dyson have been used to rationalise the composition-dependence of creep deformation in these materials. All evidence points to two important factors: (i the preferred partitioning of Re to the γ phase, where dislocation activity preferentially occurs during the tertiary creep regime and (ii a retardation effect on dislocation segments at γ/γ′ interfaces, which require non-conservative climb and thus an associated vacancy flux.

  3. The influence of heat treatment on properties of cold rolled alloyed steel and nickel superalloys sheets used in aircraft industry

    Science.gov (United States)

    Zaba, K.; Dul, I.; Puchlerska, S.

    2017-02-01

    Superalloys based on nickel and selected steels are widely used in the aerospace industry, because of their excellent mechanical properties, heat resistance and creep resistance. Metal sheets of these materials are plastically deformed and applied, inter alia, to critical components of aircraft engines. Due to their chemical composition these materials are hardly deformable. There are various methods to improve the formability of these materials, including plastic deformation at an elevated or high temperature, or a suitable heat treatment before forming process. The paper presents results of the metal sheets testing after heat treatment. For the research, sheets of two types of nickel superalloys type Inconel and of three types of steel were chosen. The materials were subjected to multivariate heat treatment at different temperature range and time. After this step, mechanical properties were examined according to the metal sheet rolling direction. The results were compared and the optimal type of pre-trial softening heat treatment for each of the materials was determined.

  4. Damage in nickel base superalloy: Influence of local parameters measured by electron backscattered diffraction and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Risbet, M. [Laboratoire Roberval, UMR 6253 UTC-CNRS, Universite de Technologie de Compiegne, BP 20529-60205 Compiegne cedex (France)], E-mail: marion.risbet@utc.fr; Feaugas, X. [Laboratoire d' Etude des Materiaux en Milieux Agressifs, EA 3127, Universite de La Rochelle, 17000 La Rochelle cedex (France); Guillemer-Neel, C. [Laboratoire de Technologies Innovantes, EA 3899, IUT Genie Mecanique d' Amiens, 80025 Amiens Cedex (France); Clavel, M. [Laboratoire Mecanique des Sols, Structures et Materiaux, UMR 8579 CNRS, Ecole Centrale Paris, 92295 Chatenay-Malabry Cedex (France)

    2009-03-15

    The low-cycle fatigue behaviour of a nickel-based superalloy has been investigated with regard to its surface damage features. This alloy endures localized plastic deformation confined in slip bands emerging as extrusions. The correlations between damage, grain orientation, the Schmid factor of slip systems and the height of extrusions have been questioned. It is proved here that reaching a critical height value is not a sufficient condition for an extrusion to induce the apparition of a transgranular crack.

  5. Crack initiation and propagation induced by inclusions in a nickel-base P/M superalloy under fatigue load

    Institute of Scientific and Technical Information of China (English)

    ZENG Yanping; ZHANG Maicang; DONG Jianxin; ZHANG Lina; XIE Xishan

    2005-01-01

    In situ fatigue tests in special designed SEM were conducted to trace the whole process of crack initiation and propagation till to fracture in nickel-base P/M superalloy seeded inclusions. The experimental results show that non-metallic inclusions can induce crack initiation. When the inclusion size is larger than the critical one, the crack can propagate as the main crack that induces the specimen to fracture. As a result, the LCF life of the specimen decreases.

  6. Alloying effects of refractory elements in the dislocation of Ni-based single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Shiyu Ma

    2016-12-01

    Full Text Available The alloying effects of W, Cr and Re in the [100] (010 edge dislocation cores (EDC of Ni-based single crystal superalloys are investigated using first-principles based on the density functional theory (DFT. The binding energy, Mulliken orbital population, density of states, charge density and radial distribution functions are discussed, respectively. It is clearly demonstrated that the addition of refractory elements improves the stability of the EDC systems. In addition, they can form tougher bonds with their nearest neighbour (NN Ni atoms, which enhance the mechanical properties of the Ni-based single crystal superalloys. Through comparative analysis, Cr-doped system has lower binding energy, and Cr atom has evident effect to improve the systemic stability. However, Re atom has the stronger alloying effect in Ni-based single crystal superalloys, much more effectively hindering dislocation motion than W and Cr atoms.

  7. Aging of a New Niobium-Modified MAR-M247 Nickel-Based Superalloy

    Science.gov (United States)

    Baldan, Renato; Azevedo e Silva, Paulo Ricardo Soares; Nunes, Carlos Angelo; Coelho, Gilberto Carvalho

    2013-08-01

    MAR-M247 is a nickel-based superalloy that contains 3 wt.% Ta (weight percent of tantalum). Considering the chemical similarity between tantalum and niobium (Nb) and the lower cost of Nb, a modified MAR-M247 superalloy was produced with total replacement of Ta by Nb in this work. The samples were previously solutioned at 1260°C for 8 h and then aged at different times (between 5 and 80 h) and temperatures (between 780 and 980°C). The microstructures of the aged samples were characterized with a scanning electron microscope (SEM and FEG-SEM, both with EDS). Simulations of the MC carbide and γ' fraction and the Ta and Nb content in both MC carbide and γ' phase were performed with Thermo-Calc software (TT_Ni8 database) and simulations of the γ' growth rate and γ' mean diameter were performed with JMatPro software. MC carbide with high Hf content was observed in all the aged samples, in agreement with thermodynamic simulation results. The equilibrium γ' fraction decreases from 67 mol.% at 780°C to 52 mol.% at 980°C. Good agreement between the calculated and experimentally determined γ' particle size was also found. The growth rate of γ' at 980°C is about 8 times higher than that at 780°C and 3 times higher than that at 880°C. The hardness values do not change considerably after aging at 780 and 880°C. However, these values decrease significantly after aging at 980°C.

  8. Hall coefficient measurement for residual stress assessment in precipitation hardened IN718 nickel-base superalloy

    Science.gov (United States)

    Velicheti, Dheeraj; Nagy, Peter B.; Hassan, Waled

    2017-02-01

    We investigated the feasibility of residual stress assessment based on Hall coefficient measurements in precipitation hardened IN718 nickel-base superalloy. As a first step, we studied the influence of microstructural variations on the galvanomagnetic properties of IN718 nickel-base superalloy. We found that the Hall coefficient of IN718 increases from ≈ 8.0×10-11 m3/C in its fully annealed state of 15 HRC Rockwell hardness to ≈ 9.4×10-11 m3/C in its fully hardened state of 45 HRC. We also studied the influence of cold work, i.e., plastic deformation, at room temperature and found that cold work had negligible effect on the Hall coefficient of fully annealed IN718, but significantly reduced it in hardened states of the material. For example, measurements conducted on fully hardened IN718 specimens showed that the Hall coefficient decreased more or less linearly with cold work from its peak value of ≈ 9.4×10-11 m3/C in its intact state to ≈ 9.0×10-11 m3/C in its most deformed state of 22% plastic strain. We also studied the influence of applied stress and found that elastic strain significantly increases the Hall coefficient of IN718 regardless of the state of hardening. The relative sensitivity of the Hall coefficient to elastic strain was measured as a unitless gauge factor K that is defined as the ratio of the relative change of the Hall coefficient ΔRH/RH divided by the axial strain ɛ = σ/E, where σ is the applied uniaxial stress and E is the Young's modulus of the material. We determined that the galvanomagnetic gauge factor of IN718 is κ ≈ 2.6 - 2.9 depending on the hardness level. Besides the fairly high value of the gauge factor, it is important that it is positive, which means that compressive stress in surface-treated components decreases the Hall coefficient in a similar way as plastic deformation does, therefore the unfortunate cancellation that occurs in fully hardened IN718 in the case of electric conductivity measurements will not

  9. Near-surface residual stresses and microstructural changes after turning of a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Schlauer, Christian

    2003-07-01

    Nickel-based superalloys are precipitation hardened alloys with complex compositions. They are used in aircraft engines and land-based gas turbines in load bearing structural components that are exposed to high temperatures. Failure mechanisms in this environment are high and low cycle fatigue, creep, and corrosion. During manufacturing, residual stresses are often introduced into the material due to inhomogeneous plastic deformations, both intentionally and unintentionally. One such manufacturing process is metal cutting, which introduces residual stresses in the surface layer. The stress state in the near-surface zone of components is of special interest as the surface often experiences peak loads and cracks have their starting point there. In this thesis, near-surface residual stress distributions and microstructural changes are studied in the nickel-based superalloy Inconel 718 for two different turning operations, face grooving and facing. Process variables are in both cases cutting speed and feed that have been varied between (10 and 1200) m/min and (0.01 and 0.5) mm, respectively. The first turning technique face grooving, which gives cutting conditions similar to orthogonal cutting, showed a clear dependency of the residual stresses on the cutting speed. The tensile stress at the surface, the maximum compressive stress below the surface, and the thickness of the affected layer increase with increasing cutting speed. The tensile stresses are constrained to a thin surface layer and compressive residual stresses below the surface dominate the depth profile of the residual stresses. Only at low cutting speed, residual stresses were largely avoided. The second turning technique facing confirmed the dependency of the residual stresses on the cutting speed and revealed a similar dependency on the feed. Microstructural investigations of near-surface cross-sections by means of transmission electron microscopy showed a zone where the grains had undergone plastic

  10. Evaluation of porosity of precision castings made of high-temperature creep resisting nickel superalloys; Beurteilung der Porositaet von Praezisionsguessen aus hochtemperaturkriechfesten Nickel-Superlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Roskosz, Stanislaw [Silesian Univ. of Technology, Katowice (Poland). Dept. of Materials Science

    2013-08-01

    The subject matter of the paper is the quantitative evaluation of gaseous and shrinkage porosity in construction elements of a low-pressure aircraft engine turbine using quantitative metallography methods. The research material consisted of blades and blade segments with a polycrystalline structure made of IN 713C and MAR M247 superalloys. One of the major problems that occur in the precision castings is their porosity: gaseous, which is the result of emission of dissolved gases from the superalloy during solidification, and shrinkage, being the result of shrinkage of the superalloy and from a lack of feeding of the interdendritic space. The comprehensive procedure of porosity evaluation includes: an automatic decimal-to-binary conversion of pores, a selective quantitative evaluation of gaseous and shrinkage porosity, the development of measuring conditions of quantitative metallography parameters, and the application of structural maps showing the varied porosity distribution over the cross-sections of castings of blades and blade segments. The developed practical procedure of selective measurement of gaseous and shrinkage porosity in the examination of precision castings made of high-temperature creep resisting nickel superalloys is presented. (orig.)

  11. Additive Manufacturing of Single-Crystal Superalloy CMSX-4 Through Scanning Laser Epitaxy: Computational Modeling, Experimental Process Development, and Process Parameter Optimization

    Science.gov (United States)

    Basak, Amrita; Acharya, Ranadip; Das, Suman

    2016-08-01

    This paper focuses on additive manufacturing (AM) of single-crystal (SX) nickel-based superalloy CMSX-4 through scanning laser epitaxy (SLE). SLE, a powder bed fusion-based AM process was explored for the purpose of producing crack-free, dense deposits of CMSX-4 on top of similar chemistry investment-cast substrates. Optical microscopy and scanning electron microscopy (SEM) investigations revealed the presence of dendritic microstructures that consisted of fine γ' precipitates within the γ matrix in the deposit region. Computational fluid dynamics (CFD)-based process modeling, statistical design of experiments (DoE), and microstructural characterization techniques were combined to produce metallurgically bonded single-crystal deposits of more than 500 μm height in a single pass along the entire length of the substrate. A customized quantitative metallography based image analysis technique was employed for automatic extraction of various deposit quality metrics from the digital cross-sectional micrographs. The processing parameters were varied, and optimal processing windows were identified to obtain good quality deposits. The results reported here represent one of the few successes obtained in producing single-crystal epitaxial deposits through a powder bed fusion-based metal AM process and thus demonstrate the potential of SLE to repair and manufacture single-crystal hot section components of gas turbine systems from nickel-based superalloy powders.

  12. Effects of cyclic stress and temperature on oxidation damage of a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Karabela, A. [Department of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ (United Kingdom); Zhao, L.G., E-mail: liguo.zhao@port.ac.uk [Department of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ (United Kingdom); Tong, J. [Department of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ (United Kingdom); Simms, N.J.; Nicholls, J.R. [School of Applied Sciences, Cranfield University, Cranfield, MK43 0AL (United Kingdom); Hardy, M.C. [Rolls-Royce plc, Elton Road, Derby DE24 8BJ (United Kingdom)

    2011-07-25

    Highlights: {yields} FIB shows the formation of surface oxide scales and internal micro-voids. {yields} Oxidation damage at 800 deg. C is much more severe than that at 700 deg. C and 750 deg. C. {yields} Cyclic stress enhances the extent of oxidation damage at 750 deg. C and above. {yields} Enrichment of Cr and Ti, as well as lower Ni and Co levels, in the surface oxides. {yields} Penetration of oxygen into the material and internal oxidation are evidenced. - Abstract: Oxidation damage, combined with fatigue, is a concern for nickel-based superalloys utilised as disc rotors in high pressure compressor and turbine of aero-engines. A study has been carried out for a nickel-based alloy RR1000, which includes cyclic experiments at selected temperatures (700-800 deg. C) and microscopy examination using focused ion beam (FIB). The results suggest that the major mechanism of oxidation damage consists of the formation of surface oxide scales and internal micro-voids and oxide particles beneath the oxide scales, which become more severe with the increase of temperature. Applying a cyclic stress does not change the nature of oxidation damage but tends to enhance the extent of oxidation damage for temperatures at 750 deg. C and 800 deg. C. The influence of cyclic stress on oxidation damage appears to be insignificant at 700 deg. C, indicating a combined effect of cyclic stress and temperature. Further energy-dispersive X-ray spectrometry (EDXS) analyses show the enrichment of Cr and Ti, together with lower Ni and Co levels, in the surface oxide scales, suggesting the formation of brittle Cr{sub 2}O{sub 3}, TiO{sub 2}, NiO and Co{sub 3}O{sub 4} oxides on the specimen surface. Penetration of oxygen into the material and associated internal oxidation, which leads to further material embrittlement and associated failure, are evidenced from both secondary ion imaging and EDXS analyses.

  13. Hot deformation of spray formed nickel-base superalloy using processing maps

    Institute of Scientific and Technical Information of China (English)

    KANG Fu-wei; ZHANG Guo-qing; LI Zhou; SUN Jian-fei

    2008-01-01

    The hot compression testing of hot isostatically pressed (HIPed) spray formed (SF) nickel-base superalloy was carried out by thermal mechanical simulator in the temperature range of 1050-1140℃ at strain rates of 0.01-10 S-1 and engineering strain of 50%. A processing map was developed on the basis of these data by using the principles of dynamic materials modeling. The microstructural evolution of deformed samples was also examined on the basis of optical and electron microscopic observations. The map exhibits two domains: the instability domain at the temperatures of 1050℃-1110℃ and strain rate of 0.01 S-1, the stability domain at the temperatures of 1110℃-1140℃ and strain rates of 1s-1-10 S-1, with a peak efficiency of about 40%. The dynamic recrystallization(DRX) is observed in the stability domain and the deformed specimens are no cracking or instabilities. However, there is no DRX in the instability domain and the alloy exhibits flow instability with cracks due to poor workability. The optimum hot working condition Was determined in the stability domain.

  14. Isothermal oxidation behavior and mechanism of a nickel-based superalloy at 1000°C

    Science.gov (United States)

    Zhu, Zhi-yuan; Cai, Yuan-fei; Gong, You-jun; Shen, Guo-ping; Tu, Yu-guo; Zhang, Guo-fu

    2017-07-01

    The oxidation behavior of a nickel-based superalloy at 1000°C in air was investigated through X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis. A series of oxides, including external oxide scales (Cr2O3, (TiO2 + MnCr2O4)) and internal oxides (Al2O3,TiN), were formed on the surface or sub-surface of the substrate at 1000°C in experimental still air. The oxidation resistance of the alloy was dependent on the stability of the surface oxide layer. The continuity and density of the protective Cr2O3 scale were affected by minor alloying elements such as Ti and Mn. The outermost oxide scale was composed of TiO2 rutile and MnCr2O4 spinel, and the growth of TiO2 particles was controlled by the outer diffusion of Ti ions through the pre-existing oxide layer. Severe internal oxidation occurred beneath the external oxide scale, consuming Al and Ti of the strength phase γ' (Ni3(Al,Ti)) and thereby severely deteriorating the surface mechanical properties. The depth of the internal oxidation region was approximately 35 μm after exposure to experimental air at 1000°C for 80 h.

  15. Effect of tube-electrode inner diameter on electrochemical discharge machining of nickel-based superalloy

    Directory of Open Access Journals (Sweden)

    Zhang Yan

    2016-08-01

    Full Text Available Nickel-based superalloys are widely employed in modern aircraft engines because of their excellent material characteristics, particularly in the fabrication of film cooling holes. However, the high machining requirement of a large number of film cooling holes can be extremely challenging. The hybrid machining technique of tube electrode high-speed electrochemical discharge drilling (TEHECDD has been considered as a promising method for the production of film cooling holes. Compared with any single machining process, this hybrid technique requires the removal of more complex machining by-products, including debris produced in the electrical discharge machining process and hydroxide and bubbles generated in the electrochemical machining process. These by-products significantly affect the machining efficiency and surface quality of the machined products. In this study, tube electrodes in different inner diameters are designed and fabricated, and the effects of inner diameter on the machining efficiency and surface quality of TEHECDD are investigated. The results show that larger inner diameters could effectively improve the flushing condition and facilitate the removal of machining by-products. Therefore, higher material removal efficiency, surface quality, and electrode wear rate could be achieved by increasing the inner diameter of the tube electrode.

  16. Effect of tube-electrode inner diameter on electrochemical discharge machining of nickel-based superalloy

    Institute of Scientific and Technical Information of China (English)

    Zhang Yan; Xu Zhengyang; Xing Jun; Zhu Di

    2016-01-01

    Nickel-based superalloys are widely employed in modern aircraft engines because of their excellent material characteristics, particularly in the fabrication of film cooling holes. How-ever, the high machining requirement of a large number of film cooling holes can be extremely chal-lenging. The hybrid machining technique of tube electrode high-speed electrochemical discharge drilling (TEHECDD) has been considered as a promising method for the production of film cooling holes. Compared with any single machining process, this hybrid technique requires the removal of more complex machining by-products, including debris produced in the electrical discharge machin-ing process and hydroxide and bubbles generated in the electrochemical machining process. These by-products significantly affect the machining efficiency and surface quality of the machined prod-ucts. In this study, tube electrodes in different inner diameters are designed and fabricated, and the effects of inner diameter on the machining efficiency and surface quality of TEHECDD are inves-tigated. The results show that larger inner diameters could effectively improve the flushing condi-tion and facilitate the removal of machining by-products. Therefore, higher material removal efficiency, surface quality, and electrode wear rate could be achieved by increasing the inner diam-eter of the tube electrode.

  17. Inertia Friction Welding Dissimilar Nickel-Based Superalloys Alloy 720Li to IN718

    Science.gov (United States)

    Huang, Z. W.; Li, H. Y.; Preuss, M.; Karadge, M.; Bowen, P.; Bray, S.; Baxter, G.

    2007-07-01

    This article describes a comprehensive microstructural characterization of an inertia friction welded joint between nickel-based superalloys 720Li and IN718. The investigation has been carried out on both as-welded and postweld heat-treated conditions. The detailed metallographic analysis has enabled the relation of hardness profiles across inertia-welded alloy 720Li to IN718 and morphological changes of the precipitates present. The work demonstrates that inertia friction welding (IFW) 720Li to IN718 results in a weld free of micropores and microcracks and no significant chemical migration across the weld line. However, substantial differences in terms of grain structure and precipitation phase distribution variations are observed on each side of the dissimilar weld. The high γ‧ volume fraction alloy 720Li exhibits a wider heat-affected zone than the mainly γ‧‧ strengthened IN718. Alloy 720Li displays only a small hardness trough near the weld line in the as-welded condition due to the depletion of γ‧, while γ″-strengthened IN718 shows a soft precipitation-free weld region. Postweld heat treatment (PWHT) of the dissimilar weld at 760 °C, a typical annealing temperature for alloy 720Li, results in an overmatch of the heat-affected zone in both sides of the weld. The comparison of the as-welded and postweld heat-treated condition also reveals that IN718 is in an overaged condition after the stress relief treatment.

  18. Grain boundary transformations during isothermal exposure of powder metallurgy nickel base superalloys for turbine disc applications

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, R.J.; Rae, C.M.F.; Tin, S.

    2005-01-15

    Nickel base superalloys are used for high pressure turbine discs, because they are capable of sustained operation under high mechanical loading at elevated temperatures. In service, turbine discs operate at high temperatures (approaching 700 deg C at the disc rim), which can lead to various microstructural changes and influence the resulting structural integrity of the component. In the alloys studied in the present work, the development of the topologically close packed phase (TCP) {sigma} has been characterised for various time and temperature combinations. The formation of {sigma} is particularly important for these alloys, as it is known to have a dramatic effect on fatigue crack growth owing to grain boundary embrittlement. In the present study, various techniques have been used to quantify the amount of {sigma} phase present for given times and temperatures, similar to those seen during operation. Both qualitative microscopy and quantitative X-ray diffraction have been conducted to establish the time-temperature-transformation relationship for {sigma} formation in two experimental turbine disc alloys. Both of the alloys studied here exhibit a low susceptibility to {sigma} formation compared with conventional alloys such as Udimet 720Li and RR1000. (Author)

  19. Deformation mechanisms of IN713C nickel based superalloy during Small Punch Testing

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, M., E-mail: m.p.coleman@swansea.ac.uk; Alshehri, H.; Banik, R.; Harrison, W.; Birosca, S.

    2016-01-05

    The role of local microstructure is critical in materials performance and integrity in a cast alloy. The grain size and grain boundary distributions as well as local texture can create various microstructure/microtexture clusters that cause deformation localisation in the alloy. Inconel 713C nickel base superalloys are used as turbocharger turbine wheels for modern diesel engines, produced via investment casting. In such an alloy localised deformation is highly expected during service, as the strain distribution is not uniform in the component due to casting geometrical factors in addition to non-homogenous microstructure and microtexture in the cast alloy. In the current investigation Small Punch (SP) tensile tests were carried out on IN713C at room temperature and 650 °C in an air environment under stroke control at a rate of 0.02 mm/s. The fracture surface examination and microstructure characterisation as well as detailed texture analyses were performed using Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD). Finite Element (FE) analysis of the SP test was also implemented to investigate the role of stress state on the local deformation. It was evident that microstructure parameters such as grain morphology and original texture existed in the disc were the most influential factors in governing the deformation texture in mixed columnar/equiaxed (transition) disc microstructure. Whereas, the temperature was the determining parameter in grain rotations and texture changes for wholly columnar disc microstructures.

  20. The Relationship Between the Solidification Parameters and Chemical Composition of Nickel Superalloy IN-713C

    Directory of Open Access Journals (Sweden)

    Binczyk F.

    2014-12-01

    Full Text Available The paper presents the results of studies on the development of correlation of solidification parameters and chemical composition of nickel superalloy IN-713C, which is used i.a. on aircraft engine turbine blades. Previous test results indicate significant differences in solidification parameters of the alloy, especially the temperatures Tliq and Tsol for each batch of ingots supplied by the manufacturer. Knowledge of such a relationship has important practical significance, because of the ability to asses and correct the temperatures of casting and heat treatment of casts on the basis of chemical composition. Using the statistical analysis it was found that the temperature of the solidification beginning Tliq is mostly influenced by the addition of carbon (similar to iron alloys. The additions of Al and Nb have smaller but still significant impact. Other alloying components do not have significant effect on Tliq. The temperature Teut is mostly affected by Ni, Ti and Nb. The temperature Tsol is not in any direct correlation with the chemical composition, which is consistent with previous research. The temperature Tsol depends primarily on the presence of non-metallic inclusions present in feed materials and introduced during the melting and casting processes.

  1. The Effect of Multi-inclined Holes on the Creep Properties of Nickel-Based Superalloy

    Science.gov (United States)

    Li, Dongfan; Wen, Zhixun; Wang, Shaofei; Liu, Chenyu; Yue, Zhufeng

    2017-07-01

    The creep properties of GH3536 nickel-based superalloy plate specimens without/with multi-inclined holes were studied under applied stress 80/90/100 MPa at 850 °, respectively. Interesting finding is focused on the inflection point, that is, both the fraction elongation and creep strain achieve the maximum value under 90 MPa. Further study is carried out by two methods: the finite element analysis (FEA) calculation and scanning electron microscope (SEM). The FEA results show that the dangerous areas appear in the regions near the end of ellipse axis along the inclined angle orientation, which is similar to the actual fracture appearances. What is more, the tiny holes and dimples are the main characters of creep fracture for multi-inclined hole specimens, whereas the creep fracture of specimens without holes is the result of growth and coalescence of voids. In addition, based on creep performance, laser drilling is better than that of the electric spark drilling, which provides a proof that the creep performance of specimens with multi-inclined holes will be better with the improvement of the drilling process.

  2. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets.

    Science.gov (United States)

    Gabriel, Tobias; Rommel, Daniel; Scherm, Florian; Gorywoda, Marek; Glatzel, Uwe

    2017-03-10

    Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co-28Cr-9W-1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE) study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM) and scanning electron microscopy (SEM), combined with electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDX). Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  3. Laser Cladding of Ultra-Thin Nickel-Based Superalloy Sheets

    Directory of Open Access Journals (Sweden)

    Tobias Gabriel

    2017-03-01

    Full Text Available Laser cladding is a well-established process to apply coatings on metals. However, on substrates considerably thinner than 1 mm it is only rarely described in the literature. In this work 200 µm thin sheets of nickel-based superalloy 718 are coated with a powder of a cobalt-based alloy, Co–28Cr–9W–1.5Si, by laser cladding. The process window is very narrow, therefore, a precisely controlled Yb fiber laser was used. To minimize the input of energy into the substrate, lines were deposited by setting single overlapping points. In a design of experiments (DoE study, the process parameters of laser power, laser spot area, step size, exposure time, and solidification time were varied and optimized by examining the clad width, weld penetration, and alloying depth. The microstructure of the samples was investigated by optical microscope (OM and scanning electron microscopy (SEM, combined with electron backscatter diffraction (EBSD and energy dispersive X-ray spectroscopy (EDX. Similarly to laser cladding of thicker substrates, the laser power shows the highest influence on the resulting clad. With a higher laser power, the clad width and alloying depth increase, and with a larger laser spot area the weld penetration decreases. If the process parameters are controlled precisely, laser cladding of such thin sheets is manageable.

  4. Annealing behavior of the ODS nickel-based superalloy PM 1000

    Energy Technology Data Exchange (ETDEWEB)

    Hayama, A.O.F.; Sandim, H.R.Z.; Lins, J.F.C.; Hupalo, M.F.; Padilha, A.F

    2004-04-25

    PM 1000 is a powder-metallurgy (P/M) nickel-based superalloy containing about 1% (volume) of fine and uniformly dispersed incoherent particles in an austenitic matrix. In the present paper, we have investigated the annealing behavior of rods deformed by cold swaging to reductions of 24 and 44% followed by annealing in temperatures varying from 800 to 1350 deg. C. The microstructural changes were followed by channeling contrast in the scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and transmission electron microscopy (TEM). Results show that discontinuous recrystallization and extended recovery are responsible for the softening of this alloy. A few grains found preferentially at grain boundary regions and within deformation heterogeneities like shear bands are able to grow corresponding to a recrystallized volume fraction lower than 10%. These new grains are arranged in colonies having a significant amount of annealing twins with {sigma}3-symmetry boundaries. The pinning effect on boundaries exerted by hard non-deformable particles (Zener drag) tends to suppress growth of most recrystallized grains. In the less deformed regions of the microstructure, a particle-stabilized subgrain structure is present and further softening is not significant even when longer annealing is performed.

  5. Laser micro-hole drilling in thermal barrier coated nickel based superalloy

    Science.gov (United States)

    Gupta, Umashanker; Nath, A. K.; Bandyopadhyay, P. P.

    2016-09-01

    This investigation deals with laser drilling of micro holes in yttria stabilised zirconia coated nickel based superalloy using a power modulated fiber laser. The parameters taken into account are assist gas pressure, modulation frequency, pulse on time and hole inclination angle. These parameters affect the important geometrical characteristics of holes, e.g., hole diameter, hole wall smoothness, taper angle and recast layer thickness. It has been found that the assist gas pressure has a significant effect on hole entry and exit diameter, taper angle and hole wall smoothness. It has also been observed less number of pulses of higher energy produces a hole with smaller entry and exit diameter, smaller taper angle, smoother hole wall and a thin stretched recast layer (∼ 15μm). The minimum achieved hole entrance diameter, exit diameter and taper was 342 μm, 200 μm and 3.54° respectively. Off normal drilling produces a hole with elliptical entrance. The eccentricity of such holes increases with inclination angle. Thick recast layers are produced at high inclination angles.

  6. Time-incremental creep–fatigue damage rule for single crystal Ni-base superalloys

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    In the present paper a damage model for single crystal Ni-base superalloys is proposed that integrates time-dependent and cyclic damage into a generally applicable time-incremental damage rule. A criterion based on the Orowan stress is introduced to detect slip reversal on the microscopic level and

  7. The Microstructure of RR1000 Nickel-Base Superalloy: The FIB-SEM Dual-Beam Approach

    Science.gov (United States)

    Croxall, S. A.; Hardy, M. C.; Stone, H. J.; Midgley, P. A.

    Nickel-base superalloys are aerospace materials that exhibit exceptional mechanical properties and corrosion resistance at very high temperatures. RR1000 is used in discs in gas turbine engines, where temperatures reach in excess of 650°C with high mechanical stresses. Study of the microstructure at the micron and sub-micron level has conventionally been undertaken using scanning electron microscope images, often meaning the underlying 3D microstructure can be inferred only with additional knowledge. Using a dual-beam workstation, we are able to interrogate directly the 3D microstructure using a serial sectioning approach. The 3D data set, typically (10µm)3 in volume, reveals microstructural detail with lateral resolution of circa 8nm and a depth resolution dictated by the slice thickness, typically 50nm. Morphological and volumetric analysis of the 3D reconstruction of RR1000 superalloy reveals microstructural details hitherto unseen.

  8. Determination of Aluminum in Nickel-Based Superalloys by Using Laser-Induced Breakdown Spectroscopy%Determination of Aluminum in Nickel-Based Superalloys by Using Laser-Induced Breakdown Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    朱德华; 王茜; 倪晓武; 陈建平; 陆建

    2011-01-01

    Laser-induced breakdown spectroscopy (LIBS) was developed to detect aluminum in nickel-based superalloys (K417, GH4033, DZ125L, З ∏742y) using a non-intensified, non-gated, low-cost detection system. The precision of LIBS depends strongly on the experimental conditions. The calibration curves of Al(I)394.4 nm and Al(I)396.2 nm under the optimum experimental parameters are presented. Finally the limit of detection (LOD) for aluminum is calculated from the experimental data, which is in the range of 0.09% to 0.1% by weight.

  9. The Improvement of Oxidation Resistance of a Re-Based Diffusion Barrier/Ni–Al Coating on the Single-Crystal Ni-Based TMS-82+ Superalloy

    NARCIS (Netherlands)

    Wu, Y.; Wang, Y.M.; Song, G.M.; Li, X.W.

    2011-01-01

    Oxidation behavior of a Re-based diffusion barrier/Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy was studied to compare with those of the base and Ni–Al coated superalloys under cyclic air at 1150 °C for 200 h. The base superalloy showed a negative mass gain due to extensive oxide spa

  10. Interdiffusion behavior between NiAlHf coating and Ni-based single crystal superalloy with different crystal orientations

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruili; Gong, Xueyuan [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Peng, Hui [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Ma, Yue, E-mail: mayue@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Guo, Hongbo, E-mail: guo.hongbo@buaa.edu.cn [School of Materials Science and Engineering, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Material and Thin Film Technology, Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), Beihang University (BUAA), No. 37, Xueyuan Road, Beijing 100191 (China)

    2015-01-30

    Highlights: • The interdiffusion behavior between the NiAlHf coating and the superalloy substrate was influenced by the crystal orientation of the substrate alloy. • The structure of TCP phases formed in SRZ and IDZ was studied. • Studying the effect of orientation crystal of substrate on the formation of SRZ. - Abstract: NiAlHf coatings were deposited onto Ni-based single crystal (SC) superalloy with different crystal orientations by electron beam physical vapor deposition (EB-PVD). The effects of the crystal orientations of the superalloy substrate on inter-diffusion behavior between the substrate and the NiAlHf coating were investigated. Substrate diffusion zone (SDZ) containing needle-like μ phases and interdiffusion zone (IDZ) mainly consisting of the ellipsoidal and rod-like μ phases were formed in the SC alloy after heat-treatment 10 h at 1100 °C. The thickness of secondary reaction zone (SRZ) formed in the SC alloy with (0 1 1) crystal orientation is about 14 μm after 50 h heat-treatment at 1100 °C, which is relatively thicker than that in the SC alloy with (0 0 1) crystal orientation, whereas the IDZ revealed similar thickness.

  11. Dynamic recrystallization behavior of a γ′-hardened nickel-based superalloy during hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongbin; Zhang, Kaifeng [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Shaosong, E-mail: jiangshaosong@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Haiping [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhao, Changhong; Yang, Xiaoli [Fushun Special Steel Co. Ltd, Fushun 113000 (China)

    2015-02-25

    Highlights: • The relationship between the peak stress and stable DRX grain size has been expressed by a power law function. • The effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature. • The effect of DDRX became stronger with the increasing strain for the alloy deformed at 1160 °C/0.1 s{sup −1}. • The fraction of twin boundaries is closely related to the deformation temperature and strain. - Abstract: The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1210 °C with a strain rate of 0.1 s{sup −1}. The electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM) were employed to investigate the effect of deformation temperature and strain on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Microstructure observations revealed that the size and volume fraction of DRX grains increased with the increasing temperature. A power exponent relationship was obtained between the stable DRX grain size and the peak stress. Additionally, it was found that the effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature, and DDRX was the operating nucleation mechanism of DRX at higher deformation temperature. On the other hand, the effect of DDRX became stronger with the increasing strain, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the later stage of deformation for the alloy deformed at 1160 °C. Nucleation of DRX can also be activated by the twinning formation. Hence, particular attention was also paid to the evolution of twin boundaries during hot deformation.

  12. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints

    Energy Technology Data Exchange (ETDEWEB)

    ME Petrichek

    2005-12-16

    a critical thickness (0.0005 in.). A diffusion barrier that exceeded this thickness would likely fail. The joint fabrication method must therefore mechanically bond the two materials causing little or no interdiffusion upon formation. Co-extrusion fits this description since it forms a mechanical joint between two materials by using heat and pressure. The two materials to be extruded are first assembled and sealed within a co-extrusion billet which is subsequently heated and then extruded through a die. For a production application, once the joint is formed, it is dejacketed to remove the outer canister. The remaining piece consists of two materials bonded together with a thin diffusion barrier. Therefore, the long-term stability of the joint is determined primarily by the kinetics of interdiffusion reaction between the two materials. An experimental design for co-extrusion of refractory metals and nickel-based superalloys was developed to evaluate this joining process and determine the long-term stability of the joints.

  13. 一种含Re单晶镍基合金的中温蠕变行为及影响因素%Creep Behavior and Its Effect Factors of a Single Crystal Nickel-Based Superalloy Containing 4.5%Re at Medium Temperature

    Institute of Scientific and Technical Information of China (English)

    田素贵; 曾征; 张超; 刘臣; 李柏松

    2013-01-01

    The influence of heat treatment techniques on medium temperature creep behaviors of the 4.5%Re single crystal nickel-base superalloy with different heat treatment regimes was investigated by means of creep curve measurement and microstructure observation. Results show that the creep property of the alloy is obviously improved with enhancing the solution temperature due to decreasing the segregation extent of the elements. After fully heat treated, the microstructure of the alloy consists of the cubic γ phase embedded coherent in the y matrix. During creep under the condition of 760 ℃/800 MPa, no rafted structure of γ phase is detected, but the twisted configuration of the γ phase is formed in the regions near the fracture. In the ranges of the applied stresses and temperatures, the alloy displays a better creep resistance and a longer creep lifetime. And the deformation features of the alloy during creep are that the dislocations move in the γ matrix channels and shear into the γ phase, the super-dislocation shearing into the γ phase can be cross-slipped from {111} planes to {100} planes to form K-W locking, or the super-dislocation shearing into the γ phase is decomposed to form the configuration of (1/3) super-Shockleys partials plus the stacking fault, which may hinder dislocations movement and restrain the cross-slipping of dislocations. This is thought to be the main reason of the alloy having a better creep resistance.%通过对合金进行不同温度的固溶处理、蠕变曲线测定及组织形貌观察,研究了热处理工艺对4.5%Re镍基单晶合金中温蠕变行为的影响.结果表明:随着固溶温度提高,可降低元素的偏析程度,提高合金的蠕变性能.在760℃/800MPa条件的蠕变期间,合金中γ’相不形成筏状组织,但在近断口区域,立方γ '相的扭曲程度增加.合金在蠕变期间的变形特征是位错在基体中运动和剪切γ'相,其中,切入γ'相的<110>超位错可由{111

  14. The Influence of Cobalt on the Microstructure of the Nickel-Base Superalloy MAR-M247

    Science.gov (United States)

    Nathal, M. V.; Maier, R. D.; Ebert, L. J.

    1982-10-01

    The influence of cobalt on the microstructure of MAR-M247, a cast nickel-base superalloy, was investigated. Nickel was substituted for Co to produce 0, 5, and the standard 10 pct Co versions of MAR-M247. The microstructures of the alloys were examined using optical and electron microscopy, X-ray diffraction, phase extraction, and differential thermal analysis. Samples were examined in as-cast, heat treated, long-time aged, and stress-rupture tested conditions. As Co was removed from MAR-M247, the γ' volume fraction decreased, the mean γ' particle size increased, the W and Ti concentrations in the γ' increased, the Cr and Al concentrations in the γ phase decreased, and the amount of carbides increased. This increase in carbide precipitation caused a change from discrete grain boundary carbides to a grain boundary film as Co level decreased.

  15. Nickel-induced crystallization of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, J A; Arce, R D; Buitrago, R H [INTEC (CONICET-UNL), Gueemes 3450, S3000GLN Santa Fe (Argentina); Budini, N; Rinaldi, P, E-mail: jschmidt@intec.unl.edu.a [FIQ - UNL, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina)

    2009-05-01

    The nickel-induced crystallization of hydrogenated amorphous silicon (a-Si:H) is used to obtain large grained polycrystalline silicon thin films on glass substrates. a-Si:H is deposited by plasma enhanced chemical vapour deposition at 200 deg. C, preparing intrinsic and slightly p-doped samples. Each sample was divided in several pieces, over which increasing Ni concentrations were sputtered. Two crystallization methods are compared, conventional furnace annealing (CFA) and rapid thermal annealing (RTA). The crystallization was followed by optical microscopy and scanning electron microscopy observations, X-ray diffraction, and reflectance measurements in the UV region. The large grain sizes obtained - larger than 100{mu}m for the samples crystallized by CFA - are very encouraging for the preparation of low-cost thin film polycrystalline silicon solar cells.

  16. Creep-Environment Interactions in Dwell-Fatigue Crack Growth of Nickel Based Superalloys

    Science.gov (United States)

    Maciejewski, Kimberly; Dahal, Jinesh; Sun, Yaofeng; Ghonem, Hamouda

    2014-05-01

    A multi-scale, mechanistic model is developed to describe and predict the dwell-fatigue crack growth rate in the P/M disk superalloy, ME3, as a function of creep-environment interactions. In this model, the time-dependent cracking mechanisms involve grain boundary sliding and dynamic embrittlement, which are identified by the grain boundary activation energy, as well as, the slip/grain boundary interactions in both air and vacuum. Modeling of the damage events is achieved by adapting a cohesive zone (CZ) approach which considers the deformation behavior of the grain boundary element at the crack tip. The deformation response of this element is controlled by the surrounding continuum in both far field (internal state variable model) and near field (crystal plasticity model) regions and the intrinsic grain boundary viscosity which defines the mobility of the element by scaling up the motion of dislocations into a mesoscopic scale. This intergranular cracking process is characterized by the rate at which the grain boundary sliding reaches a critical displacement. A damage criterion is introduced by considering the grain boundary mobility limit in the tangential direction leading to strain incompatibility and failure. Results of simulated intergranular crack growth rate using the CZ model are generated for temperatures ranging from 923 K to 1073 K (650 °C to 800 °C), in both air and vacuum. These results are compared with those experimentally obtained and analysis of the model sensitivity to loading conditions, particularly temperature and oxygen partial pressure, are presented.

  17. Air plasma-material interactions at the oxidized surface of the PM1000 nickel-chromium superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Panerai, Francesco, E-mail: panerai@vki.ac.be [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, 1640 Rhode-Saint-Genèse (Belgium); Marschall, Jochen [Molecular Physics Program, SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025 (United States); Thömel, Jan [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, 1640 Rhode-Saint-Genèse (Belgium); Vandendael, Isabelle; Hubin, Annick [Department of Materials and Chemistry, Research Group of Electrochemical and Surface Engineering, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium); Chazot, Olivier [Aeronautics and Aerospace Department, von Karman Institute for Fluid Dynamics, Chaussée de Waterloo 72, 1640 Rhode-Saint-Genèse (Belgium)

    2014-10-15

    Highlights: • A detail investigation on behavior of a Ni–Cr superalloy under air plasma is proposed. • The response of PM1000 specimens at high temperature/low pressure is characterized. • High volatility of Cr{sub 2}O{sub 3} scale in presence of oxygen is found experimentally. • Stability of NiO scale at the surface is observed. • Computed thermodynamic volatility diagrams confirm the experimental observations. - Abstract: Nickel-based superalloys are promising options for the thermal protection systems of hypersonic re-entry vehicles operating under moderate aerothermal heating conditions. We present an experimental study on the interactions between PM1000, an oxide dispersion strengthened nickel-chromium superalloy, and air plasma at surface temperatures between 1000 and 1600 K and pressures of 1500, 7500 and 10,000 Pa. Pre-oxidized PM1000 specimens are tested in high-enthalpy reactive air plasma flows generated by the Plasmatron wind tunnel at the von Karman Institute for Fluid Dynamics. Microscopic analysis of plasma-exposed specimens shows enhanced damage to the chromia scale at the lowest plasma pressure. Elemental surface analysis reveals the loss of Cr and the enhancement of Ni at the scale surface. A thermodynamic analysis supports the accelerated volatilization of Cr{sub 2}O{sub 3} and the relative stability of NiO in the presence of atomic oxygen. Changes in the reflectance and emissivity of the oxidized surfaces due to plasma-exposure are presented. The catalytic efficiencies for dissociated air species recombination are determined as a function of surface temperature and pressure through a numerical rebuilding procedure and are compared with values presented in the literature for the same material.

  18. Mechanical properties and microstructure changes after long-term aging at 700℃ for a nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    Shuangqun Zhao; Jianxin Dong; Xishan Xie

    2003-01-01

    Mechanical properties and microstructure changes have been investigated on a new nickel-base superalloy after long-term aging at 700℃. It is found that the major precipitates of the tested alloy are MC, M23C6, M6C and γ' in the course of long-term aging at 700℃. The carbides maintain good thermal stability with the aging time up to 5008 h. The growth rate of gamma prime precipitates is relatively high in the early aging period and then slows down. The coarsening behavior of gamma prime follows a diffusion-controlled growth procedure. The room temperature Rockwell hardness of the alloy aged at 700℃ increases slightly at the initial stage of aging, but it decreases with the prolonged time. It mainly depends on the size of gamma prime. In comparison with Nimonic lloy 263, the new alloy characterizes with higher tensile and stress-rupture strengths at high temperatures. The new nickel-base superalloy offers a combination of microstructure stability, strength, ductility and toughness at 700℃.

  19. Environmental effect of S02-bearing atmosphere on the creep fatigue failure of aluminide-coated MM-002 nickel-base superalloy at 870°C

    CSIR Research Space (South Africa)

    Aghion, E

    1995-04-15

    Full Text Available High-temperature low-cycle fatigue (HTLCF) failure mechanisms of aluminide-coated MAR-M002 nickel-base superalloy in air, argon and Ar+5% SO2 atmospheres were investigated at 870°C. The loading conditions were constant and consisted of creep tension...

  20. Computer Aided Design of Ni-Based Single Crystal Superalloy for Industrial Gas Turbine Blades

    Science.gov (United States)

    Wei, Xianping; Gong, Xiufang; Yang, Gongxian; Wang, Haiwei; Li, Haisong; Chen, Xueda; Gao, Zhenhuan; Xu, Yongfeng; Yang, Ming

    The influence of molybdenum, tungsten and cobalt on stress-rupture properties of single crystal superalloy PWA1483 has been investigated using the simulated calculation of JMatPro software which ha s been widely used to develop single crystal superalloy, and the effect of alloying element on the stability of strengthening phase has been revealed by using the Thermo-Calc software. Those properties calculation results showed that the increasing of alloy content could facilitate the precipitation of TCP phases and increase the lattice misfit between γ and γ' phase, and the effect of molybdenum, tantalum was the strongest and that of cobalt was the weakest. Then the chemical composition was optimized, and the selected compositions showed excellent microstructure stability and stress-rupture properties by the confirmation of d-electrons concept and software calculation.

  1. Primary and secondary dendrite spacing of Ni-based superalloy single crystals

    Directory of Open Access Journals (Sweden)

    SLOBODANKA KOSTIC

    2009-01-01

    Full Text Available Ni-based superalloy single crystals were grown by different methods (gradient method and Bridgman technique with spontaneous nucleation and with seed. In all crystal growth experiments using the Bridgman technique, the temperature gradient along the vertical furnace axes was constant (G = 33.5 °C/cm. The obtained single crystals were cut, mechanical and chemical polished, and chemically etched. Using a metallographic microscope, the spacing of the primary and secondary dendrites was investigated. The dendrite arm spacing (DAS was determined using a Quantimet 500 MC. The obtained results are discussed and compared with published data.

  2. Additional thermal fatigue data on nickel- and cobalt-base superalloys, part 1

    Science.gov (United States)

    Howes, M. A. H.

    1973-01-01

    The fluidized bed technique was used to measure the relative thermal fatigue resistance of twenty-one superalloys. Among the thirty-six variations of composition, solidification method, and surface protection the cycles to cracking differed by two to three orders of magnitude. Some alloys suffered serious weight losses and oxidation. Thermal fatigue data, oxidation, and dimensional changes are reported. The types of superalloys are identified.

  3. A New Approach of Designing Superalloys for Low Density

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Smialek, James L.; Nathal, Michael V.

    2010-01-01

    New low-density single-crystal (LDS) alloy, have bee. developed for turbine blade applications, which have the potential for significant improvements in the thrust-to-weight ratio over current production superalloys. An innovative alloying strategy was wed to achieve alloy density reductions, high-temperature creep resistance, microstructural stability, and cyclic oxidation resistance. The alloy design relies on molybdenum as a potent. lower-density solid-solution strengthener in the nickel-based superalloy. Low alloy density was also achieved with modest rhenium levels tmd the absence of tungsten. Microstructural, physical mechanical, and environmental testing demonstrated the feasibility of this new LDS superalloy design.

  4. Hot Deformation Characteristics for a Nickel-base Superalloy GH742y

    Institute of Scientific and Technical Information of China (English)

    Fuwei Kang; Jianfei Sun; Guoqing Zhang; Zhou Li

    2009-01-01

    The hot deformation characteristics of as-cast nickel-base superalloy GH742y after hot isostatic pressing (HIP)(hereafter referred to as-cast alloy) have been investigated by hot compression tests in the temperature range of 1050 to 1140℃, strain rate range of 0.01 s-1 to 10 s-1 and strain range of 35% to 50% by means of Gleeble-3500 thermal mechanical simulator.The results show that the as-cast alloy exhibits the poor deformability, and shows wedge-shaped cracking beyond the strain of 35%.At strain rates less than 1.0 s-1,the stress-strain curves exhibit nearly steady-state behavior, while at strain rate of 10 s-1, a yield drop and serrated yielding occur.The activation energy values developed on the basis of the experimental data are divided into three domains.The first domain appears at lower strain rate (≤1.0 s-1) and lower temperature (≤1080℃), with the lowest mean value of activation energy about 261.4 kJ/mol.The second domain appears at the same strain rate as the first domain, but higher temperature (>1080℃), with the intermediate mean value of activation energy about 328.8 kJ/mol.The third domain appears at higher strain rate (10 s-1) and temperature range of 1050 to 1140℃, with the largest mean value of activation energy about 605.05 kJ/mol.Three different constitutive equations are established in corresponding to domains.Microstructural observations in the third domain reveal non-uniform dynamic recrystallization (DRX) of homogeneous γ phase, which leads to the poor deformability and the highest Q value.In contrast, microstructures in the first domain show fully DRX of homogeneous γ phase, leading to the better deformability and the lowest Q value.It is noted that the grain size increases with the increment of strain rate or temperature.These results suggest that bulk metal working of this material may be carried out in the first domain where fully DRX of γ homogeneous occurred.

  5. Competing fatigue mechanisms in Nickel-base superalloy Rene 88DT

    Science.gov (United States)

    Chang, Paul N.

    Nickel base superalloys exhibit superior high temperature mechanical properties required for aircraft engine components. It has been known that the processing of these alloys by the powder metallurgy route introduces inclusions inside the material. The presence of such inclusions often leads to competing failure modes in fatigue that is described by a step-wise or two distinct S-N curves involving both the surface and internally-initiated cracks, resulting in large uncertainties of fatigue life. A clear understanding of such behavior is yet to be established. The principal objective of this research is to examine the effect of inclusions on the extent of fatigue failure competition from surface and internal initiators at two different specimen test volumes. Experimental fatigue testing has been performed to explore how the presence of inclusions affects the competing fatigue failure modes. In addition, how the competing failure modes will behave with changes in the specimen size was also studied. Two groups of material each with two different specimen sizes were used in this study. It has been shown that the two crack initiation mechanisms occurred in the small unseeded Rene 88DT specimens tested at 650ºC over the stress range tested. Additionally, the fatigue lives were reduced with increase in specimen volume. All fatigue failures in seeded material occurred due to crack initiations from the seeded inclusions. In the fatigue life of seeded material, two competing and separate S-N curves were found in small test volume, whereas, in the large test volume, the regions were separated by a "step" in S-N curve. It has been found that the largest inclusion size observed in metallographic surfaces was smaller than the size determined from the fatigue failure origin. An analysis method based on extreme value statistics developed by Murakami was used to predict the largest size of inclusion in the test volume. The results of this study clearly show that competition for

  6. Na2SO4- and NaCl- Induced Hot Corrosion Behaviors of a Nickel-Base Superalloy with Aluminide Diffusion Coating

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hot-corrosion behaviors of nickel-base superalloy and aluminide diffusion coating have been investigated in conditions of contents of Na2SO4 and NaCl molten salts at 900℃ by means of XRD and SEM.Hot-corrosion scale of the superalloy and aluminide diffusion coating were analyzed and their surface morphologies were observed.The results demonstrate that both coated and uncoated specimens are not susceptible to various contents of NaCl.That may be resulted from the Al2O3 scale formation.Growth stress was characterized by the formation of convoluted scales.

  7. Mechanical properties and development of supersolvus heat treated new nickel base superalloy AD730TM

    Directory of Open Access Journals (Sweden)

    Devaux A.

    2014-01-01

    Full Text Available The enhancement of efficiency in power generation gas turbine requires the development of new superalloys capable of withstanding higher temperatures. The development of AD730TM superalloy was achieved to provide to this new cast & wrought (C&W superalloy a higher combination between mechanical properties, microstructural stability and cost than that of other C&W superalloys with a temperature capability up to 750 ∘C. Supersolvus heat-treatment of AD730TM was studied to improve the creep properties of fine grain AD730TM superalloy which were not high enough to reach the foreseen conditions of future power generation gas turbine disks. Firstly, the grain growth was studied to select the supersolvus temperature 1120 ∘C and to obtain a homogeneous coarse grain microstructure. Then, various supersolvus heat-treatments with different cycles were tested and applied on a forged pancake with a section representative of power generation gas turbine disk. The average grain size was evaluated to be close to 200 μm for all heat-treatments. Tensile, creep, fatigue and fatigue crack growth tests were performed to compare the various heat-treatments. FEG-SEM examinations were also realized to discuss the relationships between heat-treatment, intragranular gamma prime precipitation and mechanical properties. Finally, a comparison made with other supersolvus heat treated C&W superalloys shows that AD730TM properties obtained with coarse grain microstructure are at the expected level and enable applications for power generation gas turbine discs.

  8. Development of a numerical procedure for mixed mode K-solutions and fatigue crack growth in FCC single crystal superalloys

    Science.gov (United States)

    Ranjan, Srikant

    2005-11-01

    Fatigue-induced failures in aircraft gas turbine and rocket engine turbopump blades and vanes are a pervasive problem. Turbine blades and vanes represent perhaps the most demanding structural applications due to the combination of high operating temperature, corrosive environment, high monotonic and cyclic stresses, long expected component lifetimes and the enormous consequence of structural failure. Single crystal nickel-base superalloy turbine blades are being utilized in rocket engine turbopumps and jet engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. These materials have orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Computation of stress intensity factors (SIFs) and the ability to model fatigue crack growth rate at single crystal cracks subject to mixed-mode loading conditions are important parts of developing a mechanistically based life prediction for these complex alloys. A general numerical procedure has been developed to calculate SIFs for a crack in a general anisotropic linear elastic material subject to mixed-mode loading conditions, using three-dimensional finite element analysis (FEA). The procedure does not require an a priori assumption of plane stress or plane strain conditions. The SIFs KI, KII, and KIII are shown to be a complex function of the coupled 3D crack tip displacement field. A comprehensive study of variation of SIFs as a function of crystallographic orientation, crack length, and mode-mixity ratios is presented, based on the 3D elastic orthotropic finite element modeling of tensile and Brazilian Disc (BD) specimens in specific crystal orientations. Variation of SIF through the thickness of the specimens is also analyzed. The resolved shear stress intensity coefficient or effective SIF, Krss, can be computed as a function of crack tip SIFs and the

  9. Experimental Study on the Machining of Inclined Holes for Thermal Barrier-Coated Nickel Superalloys by EDM

    Science.gov (United States)

    Zhang, Guowei; Guo, Yongfeng; Wang, Li

    2016-10-01

    Thermal barrier coatings (TBCs) are used to thermally insulate superalloy components from the hot gas streams in gas turbine engines. In this work, electrical discharge machining (EDM) was used to machine different inclined holes in TBC-coated nickel superalloys by integrating the inner-jet-liquid rotating electrode method and the assisting electrode method. The influences of the inclination angle (i.e., from 0° to 60°) and EDM parameters (i.e., peak current, pulse duration, duty factor and flushing pressure) on the machining time and electrode wear were investigated. The surface morphologies and elemental distribution were analyzed using a scanning electron microscope and an energy dispersive spectroscope. The results of the analysis showed that the 8YSZ ceramic coating is more prone to brittle fracture and cracking than the IN718 substrate and NiCoAlY bond coating, and pits and cracks become more pronounced as the inclination angle increases. The damage on the trailing edge is primarily caused by the thermal stress fracture, and the damage on the leading edge is mainly caused by thermal erosion. Using high-energy parameters, a delamination with dimensions of 28 μm (W) × 200 μm (L) occurs on the trailing edges of the coating/substrate interface.

  10. Influence of orientation and temperature on the fatigue crack growth of a nickel-based directionally solidified superalloy

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiaohua [AML, School of Aerospace, Tsinghua University, Beijing 100084 (China); Zhang, Yangyang [Beijing Institute of Space Launch Technology, Beijing 100084 (China); Shi, Huiji, E-mail: shihj@mail.tsinghua.edu.cn [AML, School of Aerospace, Tsinghua University, Beijing 100084 (China); Gu, Jialin [Department of Material Science, Tsinghua University, Beijing 100084 (China); Li, Changpeng [Corporate Technology, Siemens Ltd. (China); Kadau, Kai [Siemens Energy Inc., Charlotte (United States); Luesebrink, Oliver [Siemens Power Generation, Mulheim an der Ruhr (Germany)

    2014-11-17

    Fatigue crack growth (FCG) behaviors of a widely used nickel-based directionally solidified (DS) superalloy have been investigated. Standard compact tension (CT) specimens in longitudinal, transverse and diagonal directions are cast and tested at 25 °C, 600 °C and 850 °C to reveal the orientation and temperature dependence. The post-test fractography is observed through scanning electron microscope (SEM) and optical microscope (OM) to understand the underlying mechanism responsible for the fracture modes. Results indicate that cracks in all three orientations exhibit a similar propagating behavior, while the temperature shows a significant effect on the crack propagation regardless of the influence of orientation. It has been found that a higher temperature leads to a faster propagation rate in the initial stage due to the cyclic softening response of materials. However, the FCG rates of specimens at lower temperature speed up more rapidly and exceed those at higher temperature in the following stage. This is attributed to the crack closure effect induced by the oxidation at a much higher temperature. Therefore, a new model based on thermal activation is proposed to get a better ability for the FCG rate prediction of the DS superalloy under different temperatures.

  11. A model for life predictions of nickel-base superalloys in high-temperature low cycle fatigue

    Science.gov (United States)

    Romanoski, Glenn R.; Pelloux, Regis M.; Antolovich, Stephen D.

    1988-01-01

    Extensive characterization of low-cycle fatigue damage mechanisms was performed on polycrystalline Rene 80 and IN100 tested in the temperature range from 871 to 1000 C. Low-cycle fatigue life was found to be dominated by propagation of microcracks to a critical size governed by the maximum tensile stress. A model was developed which incorporates a threshold stress for crack extension, a stress-based crack growth expression, and a failure criterion. The mathematical equivalence between this mechanistically based model and the strain-life low-cycle fatigue law was demonstrated using cyclic stress-strain relationships. The model was shown to correlate the high-temperature low-cycle fatigue data of the different nickel-base superalloys considered in this study.

  12. Effect of cooling rate on MC carbide in directionally solidified nickel-based superalloy under high thermal gradient

    Directory of Open Access Journals (Sweden)

    Zhang Weiguo

    2012-02-01

    Full Text Available A series of directional solidification experiments have been performed to study the effect of cooling rate on the precipitation behavior of MC carbide in nickel-based superalloy under the temperature gradient of 500 K·s-1. Results reveal that the morphology of MC carbide changes from coarse block to fine strip, then to Chinese-script, and their sizes reduce gradually with the increasing of cooling rate from 2.53 K·s-1 to 36.4 K·s-1. At low cooling rates, most of these carbides are found to be located at the grain boundary and interdendritic regions, while the coupled growth of some carbides and γ matrix in the center of γ grains is occurred at high cooling rate. The main elements forming MC carbide are Ta, W, and Hf.

  13. Lifing the thermo-mechanical fatigue (TMF behaviour of the polycrystalline nickel-based superalloy RR1000

    Directory of Open Access Journals (Sweden)

    Jones Jonathan

    2014-01-01

    Full Text Available Microstructural damage and subsequent failures resulting from thermo-mechanical fatigue (TMF loading within the temperature range 300–700 ∘C are investigated for the polycrystalline nickel superalloy, RR1000. Strain controlled TMF experiments were conducted over various mechanical strain ranges, encompassing assorted phase angles, using hollow cylindrical test pieces. The paper explores two scenarios; the first where the mechanical strain range is held constant and comparisons of the fatigue life are made for different phase angle tests, and secondly, the difference between the behaviour of In-phase (IP and − 180 ∘ Out-Of-Phase (OOP tests over a variety of applied strain ranges. It is shown that different lifing approaches are currently required for the two scenarios, with a mean stress based approach being more applicable in the first case, whereas a Basquin-type model proves more appropriate in the second.

  14. Fatigue Crack Growth Behavior of Nickel-base Superalloy Haynes 282 at 550-750 °C

    Science.gov (United States)

    Rozman, K. A.; Kruzic, J. J.; Hawk, J. A.

    2015-08-01

    The fatigue crack growth rates for nickel-based superalloy Haynes 282 were measured at temperatures of 550, 650, and 750 °C using compact tension specimens with a load ratio of 0.1 and cyclic loading frequencies of 25 Hz and 0.25 Hz. Increasing the temperature from 550 to 750 °C caused the fatigue crack growth rates to increase from ~20 to 60% depending upon the applied stress intensity level. The effect of reducing the applied loading frequency increased the fatigue crack growth rates from ~20 to 70%, also depending upon the applied stress intensity range. The crack path was observed to be transgranular for the temperatures and frequencies used during fatigue crack growth rate testing. At 750 °C, there were some indications of limited intergranular cracking excursions at both loading frequencies; however, the extent of intergranular crack growth was limited and the cause is not understood at this time.

  15. Effects of aging in high temperature helium environments on room temperature tensile properties of nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Daejong [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Nuclear Materials Technology Development Division, KAERI, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Sah, Injin [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Jang, Changheui, E-mail: chjang@kaist.ac.kr [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2011-01-25

    Research highlights: {yields} Haynes 230 is susceptible to carburization, but Alloy 617 to decarburization and inter-granular oxidation. {yields} Decarburization of Nickel-base superalloys can be accelerated in impure helium with H{sub 2}. {yields} Aging heat treatment causes inter-granular fracture primarily along inter-granular oxide and grain boundary carbides, which results in the loss of ductility. {yields} Thin-plate specimen of Alloy 617 tends to favor failure by glide plane fracture when it is heavily decarburized. - Abstract: The influence of high temperature aging treatment on room temperature tensile properties of wrought nickel-base superalloys Alloy 617 and Haynes 230 was investigated. A significant decrease in elongation was observed for Alloy 617 exposed to a heavily oxidizing and decarburizing condition because of coarsening of grain boundary carbides and extensive inter-granular oxidation. On the other hand, Haynes 230 showed much lower ductility when exposed to a heavily carburizing condition, especially at 1000 deg. C because extensive carburization occurred due to a reaction with tungsten. Considerable loss of ductility for Alloy 617 and Haynes 230 was also observed in He-H{sub 2}-H{sub 2}O-CO-CO{sub 2}-CH{sub 4} and He-H{sub 2}O-CO-CO{sub 2} environments, which were the slightly oxidizing and decarburizing conditions. Loss of ductility was predominantly associated with brittle inter-granular cracking, while the extent of loss of ductility decreased depending on the decarburization depth. Decarburization was observed more extensively in helium with H{sub 2}-H{sub 2}O-CO-CO{sub 2}-CH{sub 4} than helium with H{sub 2}O-CO-CO{sub 2}, and for Alloy 617 than for Haynes 230. Finally, the role of H{sub 2} in accelerating decarburization is discussed.

  16. Investigation of nickel- and cobalt-based superalloys with protective coatings

    Science.gov (United States)

    Veksler, Yu. G.; Mal'tseva, L. A.; Pastukhov, M. V.

    2015-03-01

    The structure and composition of the surface layers of MAR-M247 and MAR-M509 superalloys are studied after the formation of protective coatings by gas-circulation aluminizing and a high-energy ion-plasma technology.

  17. Molecular dynamics study of mosaic structure in the Ni-based single-crystal superalloy

    Institute of Scientific and Technical Information of China (English)

    Zhu Tao; Wang Chong-Yu

    2006-01-01

    The mosaic structure in a Ni-based single-crystal superalloy is simulated by molecular dynamics using a potential employed in a modified analytic embedded atom method. From the calculated results we find that a closed three dimensional misfit dislocation network, with index of {100} and the side length of the mesh 89.6(A), is formed around a cuboidal γ' precipitate. Comparing the simulation results of the different mosaic models, we find that the side length of the mesh only depends on the lattice parameters of the γ and γ' phases as well as the γ/γ' interface direction, but is independent of the size and number of the cuboidal γ' precipitate. The density of dislocations is inversely proportional to the size of the cuboidal γ' precipitate, i.e. the amount of the dislocation is proportional to the total area of the γ/γ' interface, which may be used to explain the relation between the amount of the fine γ' particles and the creep rupture life of the superalloy. In addition, the closed three-dimensional networks assembled with the misfit dislocations can play a significant role in improving the mechanical properties of superalloys.

  18. Growth of Casting Microcrack and Micropore in Single-crystal Superalloys Analysed by Three-Dimensional Unit Cell

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Finite element (FE) analysis was employed to investigate the casting microcrack and micropore growth in nickel-base single-crystal superalloys DD3. Based on the finite deformation rate-dependent crystallographic constitutive equation, the simulations of casting microcrack and micropore growth in three-dimensional unit cell model were carried out in a range of parameters including stress triaxiality, Lode parameter and type of activated slip systems. The FE results show that the stress triaxiality has profound effects on growth behavior,and the Lode parameter is also important for the casting microcrack and micropore growth. The type of operative slip systems has remarkable effect on casting microcrack and micropore growth, so the life of singlecrystal component is associated with the type of activated slip systems, which is related to Schmid factor and the number of activated slip systems. The growth comparison between microcrack and micropore reveals that when the material is subjected to large deformation, the growth rate of microcrack is faster than that of micropore, i.e. microcrack is more dangerous than micropore; the microcrack is easier to result in brittle fracture than micropore. The stress triaxiality and Lode parameter have strong influence on the growth of microcrack and micropore.

  19. Dentritic morphology and microsegregation in directionally solidified superalloy, PWA-1480, single crystal: Effect of gravity; center director's discretionary fund report

    Science.gov (United States)

    Tewari, S. N.; Kumar, M. Vijaya; Lee, J. E.; Curreri, P. A.

    1990-01-01

    Primary dendrite spacings, secondary dendrite spacings, and microsegregation have been examined in PWA-1480 single crystal specimens which were directionally solidified during parabolic maneuvers on the KC-135 aircraft. Experimentally observed growth rate and thermal gradient dependence of primary dendrite spacings are in good agreement with predictions from dendrite growth models for binary alloys. Secondary dendrite coarsening kinetics show a reasonable fit with the predictions from an analytical model proposed by Kirkwood for a binary alloy. The partition coefficients of tantalum, titanium, and aluminum are observed to be less than unity, while that for tungsten and cobalt are greater than unity. This is qualitatively similar to the nickel base binaries. Microsegregation profiles experimentally observed for PWA-1480 superalloy show a good fit with Bower, Brody, and Flemings model developed for binary alloys. Transitions in gravity levels do not appear to affect primary dendrite spacings. A trend of decreased secondary arm spacings with transition from high gravity to the low gravity period was observed at a growth speed of 0.023 cm s(exp -1). However, definite conclusions can only be drawn by experiments at lower growth speeds which make it possible to examine the side-branch coarsening kinetics over a longer duration. Such experiments, not possible due to the insufficient low-gravity time of the KC-135, may be carried out in the low-gravity environment of space.

  20. Resistivity-Microstructure Relationships in Nickel Base Superalloys Used in Gas Turbine Engines for Power Generation and as Interconnects in Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gerhardt, Rosario A. [Georgia Inst. of Technology, Atlanta, GA (United States)

    2012-02-20

    This report summarizes the results accomplished during this 3-year with funds from this grant. The most important new contribution was the development of a microstructural model, based on analysis of the small angle scattering spectra that can relate the measured electrical resistivity to the precipitate population present in a nickel base superalloy in a quantitative way. A total of 24 research articles were published or were in press at the time the final report was written.

  1. The stability of lamellar gamma-gamma-prime structures. [nickel-base superalloy

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.

    1987-01-01

    The stability of stress-annealed gamma/gamma-prime lamellar structures were investigated using three nickel-base single-crystal alloys (the NASAIR 100 and two similar alloys, E and F, containing 5 and 10 wt pct Co, respectively) stress-annealed at 1000 C to form lamellae perpendicular to the applied stress. The rate of the lamellar thickening under various thermal and creep exposures was examined by SEM. For unstressed aging at 1100 C, the lamellar structures of the NASAIR and the E alloys exhibited continuous but slow lamellar coarsening, whereas the lamellae of the alloy F showed pronounced thickening plus spheroidization. Resistance to lamellar thickening was correlated with high magnitudes of lattice mismatch, which promoted a more regular lamellar structure and a finer spacing of misfit dislocations. Specimens which were tension-annealed prior to compressive creep testing exhibited an earlier onset of tertiary creep in comparison with only heat-treated specimens. This was associated with accelerated lamellar coarsening in the stress-annealed specimens.

  2. Computational and experimental observations of welds in third-generation nickel-based superalloys

    Science.gov (United States)

    Naffakh-Moosavy, Homam

    2016-02-01

    The purpose of the present study is to introduce the weld quantitative solidification paths in the newly designed third-generation superalloys. The research has been conducted using both computational and experimental approaches. The model used the Scheil solidification relations to correlate the partitioning elements with their effects on the solidification paths. Accordingly, the k values were calculated for all the participating elements in the superalloy welds. The results of model demonstrated that these were very close to unity for austenite former elements, i.e. Ni, Co, Cr and Fe, while the other elements such as Ti, Nb and Mo displayed a significant tendency for segregation. The mathematical equations were calculated for weld solidification paths of superalloys. In all the welds, a remarkable segregation behaviour was observed, especially for Nb and Ti. The solidification path equations predicted type and amount of secondary phases. The solidification paths were compared with eutectic reactions ?, and ?, on the basis of the Ni-Ti-C and Ni-Nb-C ternary phase diagrams. Both the experimental measurements and microstructural observations of eutectics exhibited an appropriate accordance with the solidification paths obtained by model calculations.

  3. Effects of cobalt concentration on the relative resistance to octahedral and cube slip in nickel-base superalloys

    Science.gov (United States)

    Bobeck, Gene E.; Miner, R. V.

    1988-11-01

    Compression yielding tests at 760 °C were performed on near [001]- and [lll]-oriented crystals of the Ni-base superalloys René 150 and a modified MAR-M247, both having two different Co concentrations. Octahedral and cube slip occurred for the near [001]- and [lll]-oriented crystals, respectively, for all compositions. For both alloy bases, increasing Co concentration was found to decrease the critical resolved shear stress for octahedral slip but to have little effect on that for cube slip. In the present work, phase analyses and variations in heat treatment indicated that the effects of Co concentration observed were not due simply to changes in the volume fraction or size of the γ' phase. It is suggested that decreasing complex stacking fault energy in the γ' with increasing Co would lead to the observed effects based on current interpretations of the dislocation locking mechanism by cube cross slip in the γ'.

  4. Superalloys 1984; Proceedings of the Fifth International Symposium, Champion, PA, October 7-11, 1984

    Energy Technology Data Exchange (ETDEWEB)

    Radavich, J.F.; Gell, M.; Kortovich, C.S.; Bricknell, R.H.; Kent, W.B.

    1984-01-01

    The papers presented in this volume provide an overview of original research, development, and applications work on iron, cobalt, and nickel superalloys intended for elevated temperature usage. Topics discussed include polycrystalline castings and properties; directionally solidified and single crystal alloys and properties; powder processing, properties, and products; and advances in processing. The discussion also covers new alloys and alloying effects as well as the environmental behavior of superalloys and fracture mechanics.

  5. Processing and characterization of Nickel-base superalloy micro-components and films for MEMS applications

    Science.gov (United States)

    Burns, Devin E.

    Microelectromechanical (MEMS) devices are not capable of withstanding harsh operating environments, which may include high temperatures, pressures and corrosive agents. Ni-base superalloys have been used successfully in the hot stages of jet turbine engines despite the presence of these conditions. In my thesis work, I developed two techniques compatible with micro-processing methods to produce Ni-base superalloy micro-components for MEMS applications. The mechanical properties of these materials were accessed at room and elevated temperatures. Microstructural studies were performed, linking microstructural features to mechanical properties. The first technique modified LIGA Ni (LIGA is a German acronym for lithography, electroplating and molding) microtensile specimens using a vapor phase aluminization process. A subsequent homogenization heat treatment produced a two phase Ni-Ni3A1 microstructure characteristic of modern Ni-base superalloys. Al composition was used to tailor both the precipitate size and volume fraction. Aluminized LIGA Ni micro-components exhibited room temperature yield and ultimate strengths 3 to 4 times LIGA Ni micro-components subject to the same heat treatment. The second technique involved sputtering a commercial Ni-base superalloy, Haynes 718, to produce thick sputtered foils (up to 20 gam) on silicon and brass substrates. The as-deposited foils were nanocrystalline solid solutions with chemical compositions similar to the bulk material. Foils subject to ageing heat treatments exhibited unique precipitation mechanisms and good thermal stability. Strengths as high as 750 MPa at 700°C were observed with several percent ductility. This is a significant improvement over state of the art metallic MEMS materials. Furthermore, a new high temperature microtensile testing technique was developed. The technique embeds a displacement based force sensor into the hot zone of a furnace. This arrangement ensures temperature uniformity during testing

  6. Analysis of Grain Boundary Character in a Fine-Grained Nickel-Based Superalloy 718

    Science.gov (United States)

    Araujo, L. S.; dos Santos, D. S.; Godet, S.; Dille, J.; Pinto, A. L.; de Almeida, L. H.

    2014-11-01

    In the current work, sheets of superalloy 718 were processed via thermomechanical route by hot and cold rolling, followed by annealing below the δ phase solvus temperature and precipitation hardening to optimum strength. Grain boundary character distribution throughout the processing was mapped via EBSD and its evolution discussed. The results show that it is possible to process the alloy to a fine grain size obtaining concomitantly a considerably high proportion of special boundaries Σ3, Σ9, and Σ27. The precipitation of δ phase presented a strong grain refining role, without significantly impairing the twinning mechanism and, consequently, the Σ3, Σ9, and Σ27 boundary formations.

  7. Preparation, Structure and Mechanical Properties of Nickel Based Porous Spherical Superalloy

    Institute of Scientific and Technical Information of China (English)

    MI Guo-fa; LI Hong-yu; LIU Xiang-yu; WANG Kuang-fei

    2009-01-01

    The porous superalloy materials with hollow spherical pores were fabricated by using metal powder sintering process.The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the pores of the porous material exhibited a uniform distribution and the apet;tures were of same size in principle.The sintering necks appeared between adjacent particles on metal skeleton after sintering.The mechanical properties of the test samples were analyzed and the result showed that this kind of materials possessed excellent energy absorption capability,and the compression resistance decreased with increasing the porosity and aperture.

  8. The development of directional coarsening of the gamma-prime precipitate in superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1983-01-01

    A study has been made of the kinetics of the directional coarsening of the gamma-prime precipitates in Ni-5.8Al-14.6Mo-6.2Ta single crystals during creep at 982 C. In this alloy, which is characterized by a large negative lattice misfit between the gamma-prime precipitate and the gamma matrix, the formation of gamma-prime rafts begins during primary creep, and the rafts grow in length as the deformation proceeds into steady-state creep. After that, the length of the rafts stabilizes. The thickness of the rafts remains constant from primary up to tertiary creep. The directional coarsening behavior of the alloy studied is similar to that of a more conventional single-crystal superalloy having a substantially smaller negative misfit.

  9. Analysis of gamma prime shape changes in a single crystal Ni-base superalloy

    Science.gov (United States)

    Gayda, J.; Mackay, R. A.

    1989-01-01

    The microstructural evolution of a commercial single crystal superalloy, NASAIR 100, is analyzed using the existing high-temperature lattice mismatch data and high-temperature moduli obtained from tests on single crystals of gamma and gamma prime. A multiparticle analysis of the microstructural evolution is performed using a novel microstructural lattice simulation technique, MCFET. Under a uniaxial stress, a regular array of gamma prime particles in the simulated microstructure is predicted to coalesce and form a plate morphology, with the broad faces of the plates and stress axis perpendicular in tension but parallel in compression. These results are consistent with changes in gamma prime shape observed in NASAIR 100 following creep testing at 1000 C.

  10. Shock induced crystallization of amorphous Nickel powders

    Science.gov (United States)

    Cherukara, Mathew; Strachan, Alejandro

    2015-06-01

    Recent experimental work has shown the efficacy of amorphous Ni/crystalline Al composites as energetic materials, with flame velocities twice that of a comparable crystalline Ni/crystalline Al system. Of further interest is the recrystallization mechanisms in the pure amorphous Ni powders, both thermally induced and mechanically induced. We present large-scale molecular dynamics simulations of shock-induced recrystallization in loosely packed amorphous Nickel powders. We study the time dependent nucleation and growth processes by holding the shocked samples at the induced pressures and temperatures for extended periods following the passage of the shock (up to 6 ns). We find that the nanostructure of the recrystallized Ni and time scales of recrystallization are dependent on the piston velocity. At low piston velocities, nucleation events are rare, leading to long incubation times and a relatively coarse nanostructure. At higher piston velocities, local variations in temperature due to jetting phenomena and void collapse, give rise to multiple nucleation events on time scales comparable to the passage of the shock wave, leading to the formation of a fine-grained nanostructure. Interestingly, we observe that the nucleation and growth process occurs in two steps, with the first nuclei crystallizing into the BCC structure, before evolving over time into the expected FCC structure. U.S. Defense Threat Reduction Agency, HDTRA1-10-1-0119 (Program Manager Suhithi Peiris).

  11. The development of gamma-gamma-prime lamellar structures in a nickel-base superalloy during elevated temperature mechanical testing

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1985-01-01

    The kinetics of the formation and subsequent development of the directional coarsening of the gamma-prime precipitate in model Ni-Al-Mo-Ta superalloy single crystals are examined during tensile creep under various stress levels at 982 and 1038 C. Special attention is given to the gamma and gamma-prime relation to creep time and strain in order to trace the changing gamma-gamma-prime morphology. Directional coarsening of gamma-prime is found to begin during primary creep and its rate is shown to increase with an increase in temperature or stress level. The length of gamma-prime thickness increased linearly with time up to a plateau reached after the onset of steady state creep. The raft thickness, equal to the gamma-prime size, remained constant at this initial value up through the onset of the tertiary creep. The interlaminar spacing indicates the stability of directionally coarsened structure.

  12. Advanced Ni base superalloys for small gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, J.B.; Harris, K.

    2011-07-15

    Nickel base superalloy materials have extensive applications in the hot turbine section of aero and industrial gas turbine engines. They provide a unique combination of characteristics suitable for higher temperature strength and durability requirements and are also applicable to small turbine and missile engines. Specific considerations pertinent to selection of superalloys for small gas turbine engines include not only overall mechanical properties, but also the changes in properties over time due to operation, reduction in properties for thin wall applications compared to thick section database values, alloy density and the effect on disc and shaft alloy selection, and always, material/component costs. Nickel base superalloys were first introduced into military gas turbine engines during the Second World War and the technology has advanced dramatically since that time, including conventionally cast equiax (EQ) alloys, directionally solidified (DS) and single crystal (SX) cast components. This paper discusses the characteristics and applications of each casting technology.

  13. MICROMECHANICS OF THE DAMAGE-INDUCED CELLULAR MICROSTRUCTURE IN SINGLE CRYSTAL Ni-BASED SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    M.Sakaguchi; M.Okazaki

    2004-01-01

    An analytical method to investigate the morphological evolution of the cellular microstructure is explored and proposed. The method is essentially based on the Eshelby's micromechanics theory, and it is extended so as to be applied for a material system containing inclusions with high volume fraction, by employing the average stress field approximation by Mori and Tanaka. The proposed method enables us to discuss a stable shape of precipitate in the material system, which must be influenced by many factors: e.g., volume fraction of precipitate; Young's modulus ratio and lattice misfit between matrix and precipitate; external stress field in multiaxial state; and heterogeneity of plastic strain between matrix and precipitate. A series of numerical calculations were summarized on stable shape maps. The application of the method to predict the γ' rafting in superalloys during creep showed that the heterogeneity of plastic strain between matrix and precipitates may play a significant role in the shape stability of the precipitate. Furthermore, it was shown that the method was successfully applied to estimate the morphology of the cellular microstructure formed in CMSX-4single crystal Ni-based superalloy.

  14. The cyclic oxidation behavior of the single crystal TMS-82+ superalloy in humidified air

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Y. [School of Materials Science and Engineering, Shanghai, Institute of Technology, Shanghai (China); Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan); Narita, T. [Research Group of Interface Control Engineering, Graduate School of Engineering, Hokkaido University, Sapporo (Japan)

    2009-10-15

    The cyclic oxidation behavior of a single crystal Ni-based superalloy TMS-82+ was studied at 800 and 900 C for 200 h in water vapor (air plus 15% H{sub 2}O). Regardless of the exposure temperature, time-dependence of the growth rate of the scale for the superalloy was fitted by a subparabolic relationship. The oxidation rate was enhanced with increase in exposure temperature, which was evidenced by a higher mass gain and thicker scale. The oxides on the specimen at 800 C consisted of (Ni,Co)O, CrTaO{sub 4}, AlTaO{sub 4}, Cr{sub 2}O{sub 3}, and {theta}-Al{sub 2}O{sub 3}, whereas for the specimen exposed at 900 C, spinels of NiCr{sub 2}O{sub 4} and (Ni,Co)Al{sub 2}O{sub 4} as well as {alpha}-Al{sub 2}O{sub 3} were observed. An innermost dense {alpha}-Al{sub 2}O{sub 3} layer was responsible for a stable growth rate of the scale after the initial rapid oxidation. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  15. Strain Amount Dependent Grain Size and Orientation Developments during Hot Compression of a Polycrystalline Nickel Based Superalloy

    Directory of Open Access Journals (Sweden)

    Guoai He

    2017-02-01

    Full Text Available Controlling grain size in polycrystalline nickel base superalloy is vital for obtaining required mechanical properties. Typically, a uniform and fine grain size is required throughout forging process to realize the superplastic deformation. Strain amount occupied a dominant position in manipulating the dynamic recrystallization (DRX process and regulating the grain size of the alloy during hot forging. In this article, the high-throughput double cone specimen was introduced to yield wide-range strain in a single sample. Continuous variations of effective strain ranging from 0.23 to 1.65 across the whole sample were achieved after reaching a height reduction of 70%. Grain size is measured to be decreased from the edge to the center of specimen with increase of effective strain. Small misorientation tended to generate near the grain boundaries, which was manifested as piled-up dislocation in micromechanics. After the dislocation density reached a critical value, DRX progress would be initiated at higher deformation region, leading to the refinement of grain size. During this process, the transformations from low angle grain boundaries (LAGBs to high angle grain boundaries (HAGBs and from subgrains to DRX grains are found to occur. After the accomplishment of DRX progress, the neonatal grains are presented as having similar orientation inside the grain boundary.

  16. Effect of B, Zr, and C on Hot Tearing of a Directionally Solidified Nickel-Based Superalloy

    Science.gov (United States)

    Grodzki, J.; Hartmann, N.; Rettig, R.; Affeldt, E.; Singer, R. F.

    2016-06-01

    The effect of the minor elements B, Zr, and C on the castability of a Nickel-based γ'-strengthened superalloy has been investigated. Tube-like specimens were prepared by directional solidification where the rigid ceramic core leads to hoop stresses and grain boundary cracking. It was found that an important improvement in castability can be achieved by adjusting the minor elemental composition. Too low C (≤0.15 pct) and too high B and Zr contents (≥0.05 pct) lead to material that is very prone to solidification cracking and should be avoided. The results cannot be rationalized on the basis of the current models for solidification cracking. Instead, pronounced hot tearing is observed to occur at high amounts of γ/ γ'-eutectic and high Zr contents. The critical film stage where dendrites at the end of solidification do not touch and are separated by thin liquid films must be avoided. How Zr promotes the film stage will be discussed in the paper.

  17. Effect of Notches on Creep-Fatigue Behavior of a P/M Nickel-Based Superalloy

    Science.gov (United States)

    Telesman, Jack; Gabb, Timothy P.; Ghosn, Louis J.; Gayda, John, Jr.

    2015-01-01

    A study was performed to determine and model the effect of high temperature dwells on notched low cycle fatigue (NLCF) and notch stress rupture behavior of a fine grain LSHR powder metallurgy (PM) nickel-based superalloy. It was shown that a 90 second dwell applied at the minimum stress (min dwell) was considerably more detrimental to the NLCF lives than similar dwell applied at the maximum stress (max dwell). The short min dwell NLCF lives were shown to be caused by growth of small oxide blisters which caused preferential cracking when coupled with high concentrated notch root stresses. The cyclic max dwell notch tests failed mostly by a creep accumulation, not by fatigue, with the crack origin shifting internally to a substantial distance away from the notch root. The classical von Mises plastic flow model was unable to match the experimental results while the hydrostatic stress profile generated using the Drucker-Prager plasticity flow model was consistent with the experimental findings. The max dwell NLCF and notch stress rupture tests exhibited substantial creep notch strengthening. The triaxial Bridgman effective stress parameter was able to account for the notch strengthening by collapsing the notched and uniform gage geometry test data into a singular grouping.

  18. The potential link between high angle grain boundary morphology and grain boundary deformation in a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Jennifer L.W., E-mail: jennifer.w.carter@case.edu [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States); Sosa, John M. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Shade, Paul A. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Fraser, Hamish L. [Center for Accelerated Maturation of Materials, The Ohio State University, Columbus, OH 44321 (United States); Uchic, Michael D. [Air Force Research Laboratory, Materials & Manufacturing Directorate, AFRL/RXCM, Wright-Patterson AFB, Dayton, OH 45433 (United States); Mills, Michael J. [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 44321 (United States)

    2015-07-29

    Focused ion beam (FIB) based serial sectioning was utilized to characterize the morphology of two high angle grain boundaries (HAGB) in a nickel based superalloy, one that experienced grain boundary sliding (GBS) and the other experienced strain accumulation, during elevated temperature constant stress loading conditions. A custom script was utilized to serial section and collect ion-induced secondary electron images from the FIB-SEM system. The MATLAB based MIPAR{sup TM} software was utilized to align, segment and reconstruct 3D volumes from the sectioned images. Analysis of the 3D data indicates that the HAGB that exhibited GBS had microscale curvature that was planar in nature, and local serrations on the order of ±150 nm. In contrast, the HAGB that exhibited strain accumulation was not planar and had local serrations an order of magnitude greater than the other grain boundary. It is hypothesized that the serrations and the local grain boundary network are key factors in determining which grain boundaries experience GBS during creep deformation.

  19. Multi-objective constrained design of nickel-base superalloys using data mining- and thermodynamics-driven genetic algorithms

    Science.gov (United States)

    Menou, Edern; Ramstein, Gérard; Bertrand, Emmanuel; Tancret, Franck

    2016-06-01

    A new computational framework for systematic and optimal alloy design is introduced. It is based on a multi-objective genetic algorithm which allows (i) the screening of vast compositional ranges and (ii) the optimisation of the performance of novel alloys. Alloys performance is evaluated on the basis of their predicted constitutional and thermomechanical properties. To this end, the CALPHAD method is used for assessing equilibrium characteristics (such as constitution, stability or processability) while Gaussian processes provide an estimate of thermomechanical properties (such as tensile strength or creep resistance), based on a multi-variable non-linear regression of existing data. These three independently well-assessed tools were unified within a single C++ routine. The method was applied to the design of affordable nickel-base superalloys for service in power plants, providing numerous candidates with superior expected microstructural stability and strength. An overview of the metallurgy of optimised alloys, as well as two detailed examples of optimal alloys, suggest that improvements over current commercial alloys are achievable at lower costs.

  20. Determination of thermophysical and structural properties of nickel super-alloy

    Directory of Open Access Journals (Sweden)

    S. Zlá

    2015-10-01

    Full Text Available In this work the differential thermal analysis (DTA was selected for the study of 718Plus super-alloy. Particular attention was paid to determination of the phase transformation temperatures (liquidus, γ´ precipitation temperature, etc.. Almost at all temperatures of samples an undercooling was observed. Shifting of almost all temperatures was observed in the heating/cooling mode towards higher values with an increasing rate of heating, lower values with the increasing cooling rate. On the basis of DTA and structural analysis it may be stated that development of phase transformations will probably correspond to the following scheme: melting → γ phase; melting → γ + MC (NbC, TiC; melting + MC → γ + Laves + σ; γ → γ´ (γ´´.

  1. Formation of Minor Phases in a Nickel-Based Disk Superalloy

    Science.gov (United States)

    Gabb, T. P.; Garg, A.; Miller, D. R.; Sudbrack, C. K.; Hull, D. R.; Johnson, D.; Rogers, R. B.; Gayda, J.; Semiatin, S. L.

    2012-01-01

    The minor phases of powder metallurgy disk superalloy LSHR were studied. Samples were consistently heat treated at three different temperatures for long times to approximate equilibrium. Additional heat treatments were also performed for shorter times, to then assess non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their transformation temperatures, lattice parameters, compositions, average sizes and total area fractions were determined, and compared to estimates of an existing phase prediction software package. Parameters measured at equilibrium sometimes agreed reasonably well with software model estimates, with potential for further improvements. Results for shorter times representing non-equilibrium indicated significant potential for further extension of the software to such conditions, which are more commonly observed during heat treatments and service at high temperatures for disk applications.

  2. Structure-property effects of tantalum additions to nickel-base superalloys

    Science.gov (United States)

    Heckel, R. W.; Pletka, B. J.; Koss, D. A.; Jackson, M. R.

    1982-01-01

    The characterization of the effect of Ta on the structure of Ni base superalloys, the determination of the effects of Ta (structure) variations on the mechanical, thermal, and oxidation behavior, and the identification of alloying elements which have potential as substitutes for Ta are investigated. Mar M247 type alloys are emphasized; nominal and analyzed compositions of ten alloys under study are given. X-ray and composition analysis are being used to determine the partitioning of alloying elements between gamma, gamma primes, and MC (cubic) as a function of Ta content. The diffusional interactions of the Mar M247-type alloys with as cast beta + gamma alloys are studied to determine the effects of Ta on alloy/coating degradation.

  3. Environment assisted crack growth in nickel-base superalloys at elevated temperature

    Science.gov (United States)

    Evans, Jeffrey Lee

    The environmental effect on the fatigue crack growth rate of Ni-base superalloys at elevated temperature was evaluated in this study. A set of crack growth tests was performed on the turbine disk alloy ME3 at 704°C (1300°F) in vacuum and in air at 0 and 10 second hold times using two microstructures developed with two different cooling rates from the solution heat treat temperature. Fatigue crack growth tests were also conducted at 25°C (77°F) with the two microstructures. Also, a set of oxidation experiments was conducted in order to evaluate the high temperature oxidation behavior of ME3. The microstructure was analyzed and the main differences between the two cooling rates were in the amounts of minor phase particles and size of secondary gamma prime particles. The crack growth rate results suggest that there is no measurable effect of environment or microstructure at room temperature. For the tests conducted in air at elevated temperature, both hold time and microstructural effects were evident. A coupling effect was also observed between the microstructure and the environment. The samples that were slow cooled, and had larger secondary gamma prime particles, had slower crack growth rates and less intergranular fracture in air than the fast cooled samples. A possible explanation for this would be excess free chromium available along grain boundaries due to its low solubility in gamma prime, providing for greater oxidation resistance. An elevated temperature fatigue crack growth rate model for Ni-base superalloys is also proposed.

  4. Solutioning and Aging of MAR-M247 Nickel-Based Superalloy

    Science.gov (United States)

    Baldan, Renato; da Rocha, Rafaela Lisboa Pereira; Tomasiello, Rafael Bogado; Nunes, Carlos Angelo; da Silva Costa, Alex Matos; Barboza, Miguel Justino Ribeiro; Coelho, Gilberto Carvalho; Rosenthal, Ruben

    2013-09-01

    Despite the existence of previous studies on the heat treatment of the MAR-M247 superalloy, there is a lack of microstructural characterization data that support the heat-treatment conditions that are proposed in this study. Thus, the aim of this study is to investigate the changes in microstructure that occur in this alloy when subjected to different solutioning and aging heat treatments. Thermodynamic calculations and differential thermal analysis guided the experimental design and the analysis of experimental results. The MAR-M247 superalloy was produced via vacuum induction melting and investment casting. The samples were solutioned between 1185 and 1270 °C and aged between 770 and 980 °C. The as-cast and heat-treated samples were characterized using scanning electron microscopy in backscattered electron and secondary electron modes. Thermodynamic calculations have shown that the minimum solutioning temperature is approximately 1220 °C, occurring in a γ + MC + MB2 three-phase field (M = metal). The samples were solutioned at 1250 °C for 310 min before aging heat treatment. During solutioning the carbide composition is the MC phase shifts to higher hafnium (Hf) and lower tantalum (Ta) content, which is in agreement with the thermodynamics calculations. After solutioning, residual aluminum (Al) segregation leads to the formation of large γ' particles in certain regions of the material following one-step aging heat treatment at 770 and 870 °C. However, a nearly uniform size distribution of γ' particles was observed after aging at 980 °C as well as after double aging heat treatment at 980 °C for 300 min + 870 °C for 1200 min.

  5. A novel unified dislocation density-based model for hot deformation behavior of a nickel-based superalloy under dynamic recrystallization conditions

    Science.gov (United States)

    Lin, Y. C.; Wen, Dong-Xu; Chen, Ming-Song; Chen, Xiao-Min

    2016-09-01

    In this study, a novel unified dislocation density-based model is presented for characterizing hot deformation behaviors in a nickel-based superalloy under dynamic recrystallization (DRX) conditions. In the Kocks-Mecking model, a new softening item is proposed to represent the impacts of DRX behavior on dislocation density evolution. The grain size evolution and DRX kinetics are incorporated into the developed model. Material parameters of the developed model are calibrated by a derivative-free method of MATLAB software. Comparisons between experimental and predicted results confirm that the developed unified dislocation density-based model can nicely reproduce hot deformation behavior, DRX kinetics, and grain size evolution in wide scope of initial grain size, strain rate, and deformation temperature. Moreover, the developed unified dislocation density-based model is well employed to analyze the time-variant forming processes of the studied superalloy.

  6. Effects of Thermal Exposure on Structures of DD6 Single Crystal Superalloy with Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    DONG Jianmin

    2016-10-01

    Full Text Available In order to investigate the effect of water grit-blasting and high temperature thermal exposure on the microstructures of DD6 alloy with TBCs, DD6 single crystal superalloy specimens were water grit-blasted with 0.3 MPa pressure, then the specimens were coated with thermal barrier coatings by electron beam physical vapor deposition (EB-PVD. Specimens with TBCs were exposed at 1100℃ for 50 and 100 hours in the air respectively, and then these specimens were subjected to stress-rupture tests under the condition of 1100℃/130 MPa. The results show that grit-blasting doesn't lead into the recrystallization, thermal exposure can induce element interdiffusion between the bond coat and alloy substrate, the residual stress and element diffusion lead into the changes of γ' phase coarsing direction. After stress rupture tests, the secondary reaction zone emerges into a local area.

  7. Comparative Investigation of the Downward and Upward Directionally Solidified Single-Crystal Blades of Superalloy CMSX-4

    Science.gov (United States)

    Wang, Fu; Ma, Dexin; Bogner, Samuel; Bührig-Polaczek, Andreas

    2016-05-01

    Single-crystal blades of Ni-base superalloys CMSX-4 have been directionally solidified using the downward directional solidification (DWDS) process. The possible benefits of the process were comparatively evaluated with respect to the Bridgman process' results. The DWDS process exhibits good capabilities for casting the single-crystal components. The thermal gradients of this process are approximately seven times higher than those of the Bridgman process. It provides more advantages for solidifying the single-crystal superalloy blades by reducing the casting defects, refining the microstructure, decreasing the size of the γ/ γ' eutectic pools, refining the γ' precipitates, alleviating the degree of the microsegregation, and minimizing the size and volume fraction of the micropores.

  8. Influence of heat treatment on microstructure and tensile behavior of a hot isostatically pressed nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Chunlei, E-mail: c.qiu@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Wu, Xinhua; Mei, Junfa [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Andrews, Paul; Voice, Wayne [Rolls-Royce Plc, Derby DE24 8BJ (United Kingdom)

    2013-11-25

    Highlights: •Post-HIP heat treatment led to refined microstructure and improved tensile properties. •Deformation occurred mainly by forming stacking faults in γ′ at RT and elevated temperature. •Net-shape HIPed RR1000 failed in a transgranular fracture mode. -- Abstract: A nickel-based superalloy powder RR1000 has been hot isostatically pressed (HIPed) and heat treated to produce different microstructures. Microstructures were investigated using a scanning electron microscope (SEM). Tensile testing was performed at room temperature and 700 °C and the deformed samples were examined using SEM and transmission electron microscope (TEM). It was found that in the as-HIPed condition the microstructure consisted of coarse and irregular-shaped primary and secondary γ′ together with a low volume fraction of fine γ′ (<50 nm in diameter). Solution treatment below the γ′ solvus followed by air cooling resulted in the formation of finer cuboidal secondary γ′ (350–750 nm) and medium-sized spherical tertiary γ′ (100–200 nm). This led to an improvement of both the 0.2% yield strength and ultimate tensile strength. Ageing of the solution-treated or of the as-HIPed samples at 760 °C resulted in the precipitation of a high population of fine γ′ (around 50 nm) which further increased the strength. Within the resolution limit of the current TEM analysis, deformation at room temperature seemed to occur mainly by dislocations cutting through secondary γ′ and very fine γ′, accompanied by the formation of stacking faults within these precipitates; most of the medium-sized tertiary γ′ precipitates in solution-treated and aged samples were not cut through but were surrounded by dislocations. Deformation at 700 °C happened by dislocations cutting through γ′ precipitates and γ matrix, leading to the formation of extended stacking faults across both γ and γ′. It is suggested that the optimum treatment of the current powder superalloy is to

  9. Effect of microstructure on high-temperature mechanical behavior of nickel-base superalloys for turbine disc applications

    Science.gov (United States)

    Sharpe, Heather Joan

    2007-05-01

    Engineers constantly seek advancements in the performance of aircraft and power generation engines, including, lower costs and emissions, and improved fuel efficiency. Nickel-base superalloys are the material of choice for turbine discs, which experience some of the highest temperatures and stresses in the engine. Engine performance is proportional to operating temperatures. Consequently, the high-temperature capabilities of disc materials limit the performance of gas-turbine engines. Therefore, any improvements to engine performance necessitate improved alloy performance. In order to take advantage of improvements in high-temperature capabilities through tailoring of alloy microstructure, the overall objectives of this work were to establish relationships between alloy processing and microstructure, and between microstructure and mechanical properties. In addition, the projected aimed to demonstrate the applicability of neural network modeling to the field of Ni-base disc alloy development and behavior. The first phase of this work addressed the issue of how microstructure varies with heat treatment and by what mechanisms these structures are formed. Further it considered how superalloy composition could account for microstructural variations from the same heat treatment. To study this, four next-generation Ni-base disc alloys were subjected to various controlled heat-treatments and the resulting microstructures were then quantified. These quantitative results were correlated to chemistry and processing, including solution temperature, cooling rate, and intermediate hold temperature. A complex interaction of processing steps and chemistry was found to contribute to all features measured; grain size, precipitate distribution, grain boundary serrations. Solution temperature, above a certain threshold, and cooling rate controlled grain size, while cooling rate and intermediate hold temperature controlled precipitate formation and grain boundary serrations. Diffusion

  10. Microstructure and Creep Property of a GH4169 Nickel-based Superalloy

    Directory of Open Access Journals (Sweden)

    LIU Chen

    2017-06-01

    Full Text Available By means of direct aging (DA heat treatment, creep properties measurement and microstructure observation, the microstructure and creep behaviors of the GH4169 superalloy were investigated. Results show that the microstructure of the alloy consists of γ, γ', γ" and δ phases, and the coherent interfaces exist between the phases. The creep life of the alloy at 660℃/700 MPa is predicted to be 123h, and 39h at 680℃/700MPa. Under the testing temperature and stress range, the creep activation energy of the alloy is calculated to be 588.0 kJ/mol. The deformation mechanisms of the alloy during creep are dislocation slipping and twin deformation. The granular carbides precipitated along the grain boundaries may restrain the slipping of the boundary, which is thought to be the main reason of the good creep resistance. As the creep goes on, the slipping dislocations activated within the grains are hindered and blocked by the boundaries to cause the stress concentration, which may promote the initiation and propagation of the crack occurring along the boundaries perpendicular to the stress axis, when the value of stress concentration is higher than the bonding strength of the boundaries, up to the occurrence of creep fracture. This is thought to be the fracture mechanism of alloy during creep.

  11. Hardening anisotropy of {gamma}/{gamma}{prime} superalloy single crystals. 1: Experimental estimates at 650 C from a homogeneous analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hoinard, G.; Estevez, R.; Franciosi, P. [Univ. Paris Nord, Villetaneuse (France)

    1995-04-01

    The hardening anisotropy, in quasi static loading, of {gamma}/{gamma}{prime} superalloy single crystals is experimentally investigated and analyzed according to a description of crystal hardening at the dislocation density and interaction scale, and regardless of the two-phase nature of the material. A matrix of hardening coefficients is estimated from monotonous and sequential loadings at 650 C on <001>, <011>, <111> oriented samples of two different alloys with similar compositions and structures. This hardening analysis distinguishes three types of slip systems all having the <110> type slip direction: octahedral systems with an easy or an uneasy dislocation motion direction, and cubic systems. The estimated interactions between these system pairs separate, within each of the three system groups, a coplanar (including self interaction) coefficient with a non coplanar one. As a whole, the superalloy single crystal hardening anisotropy at this medium temperature comes out comparable to one of the most anisotropic pure f.c.c. metals, mainly because of the hardening asymmetry on the octahedral systems. If the asymmetry is averaged, the remaining anisotropy falls down to the anisotropy level of high stacking fault energy f.c.c. metals. These quantitative estimates are limited by the questionable assumption of homogeneous behavior for such a two-phase crystal structure. Analyses accounting for both the crystalline structure and the two-phase nature of these superalloys will be the purpose of the forthcoming Part 2.

  12. 高温合金精密铸造技术研究进展%The Progress of Investment Casting of Nickel-Based Superalloys

    Institute of Scientific and Technical Information of China (English)

    刘林

    2012-01-01

    This paper reviews the principle, techniques, research statues and current problems of major processing technologies of casi superalloys, such as polycrystalline casting, directional solidification, single-crystal manufacture. The cast structure control and crystal orientation selection during solidification were analyzed. Single-crystal processing including bottom-seeding and spiral selection technique was summarized. The formation mechanism and control methods of typical cast defects in single crystal superalloys were analyzed. Finally, the possible development trends of the superalloy investment casting in future were prospected.%综述了高温合金多晶铸造、定向凝固、单晶制备等几种主要制备技术的原理、方法、研究现状和存在问题,分析了铸造高温合金晶粒组织控制、晶体取向选择和控制,介绍了单晶叶片的引晶和选晶原理和技术,对单晶铸造高温合金的缺陷进行了分析,并展望了高温合金精密铸造的今后发展方向.

  13. Constitutive modeling of creep behavior in single crystal superalloys: Effects of rafting at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ya-Nan, E-mail: fanyn12@mails.tsinghua.edu.cn; Shi, Hui-Ji, E-mail: shihj@mail.tsinghua.edu.cn; Qiu, Wen-Hui

    2015-09-17

    Rafting and creep modeling of single crystal superalloys at high temperatures are important for the safety assessment and life prediction in practice. In this research, a new model has been developed to describe the rafting evolution and incorporated into the Cailletaud single crystal plasticity model to simulate the creep behavior. The driving force of rafting is assumed to be the relaxation of the strain energy, and it is calculated with the local stress state, a superposition of the external and misfit stress tensors. In addition, the isotropic coarsening is introduced by the cube root dependence of the microstructure periodicity on creep time based on Ostwal ripening. Then the influence of rafting on creep deformation is taken into account as the Orowan stress in the single crystal plasticity model. The capability of the proposed model is validated with creep experiments of CMSX-4 at 950 °C and 1050 °C. It is able to predict the rafting direction at complex loading conditions and evaluate the channel width during rafting. For [001] tensile creep tests, good agreement has been shown between the model predictions and experimental results at different temperatures and stress levels. The creep acceleration can be captured with this model and is attributed to the microstructure degradation caused by the precipitate coarsening.

  14. Automated detection and characterization of microstructural features: application to eutectic particles in single crystal Ni-based superalloys

    Science.gov (United States)

    Tschopp, M. A.; Groeber, M. A.; Fahringer, R.; Simmons, J. P.; Rosenberger, A. H.; Woodward, C.

    2010-03-01

    Serial sectioning methods continue to produce an abundant amount of image data for quantifying the three-dimensional nature of material microstructures. Here, we discuss a methodology to automate detecting and characterizing eutectic particles taken from serial images of a production turbine blade made of a heat-treated single crystal Ni-based superalloy (PWA 1484). This method includes two important steps for unassisted eutectic particle characterization: automatically identifying a seed point within each particle and segmenting the particle using a region growing algorithm with an automated stop point. Once detected, the segmented eutectic particles are used to calculate microstructural statistics for characterizing and reconstructing statistically representative synthetic microstructures for single crystal Ni-based superalloys. The significance of this work is its ability to automate characterization for analysing the 3D nature of eutectic particles.

  15. Relationships between Microstructural Parameters and Time-Dependent Mechanical Properties of a New Nickel-Based Superalloy AD730™

    Directory of Open Access Journals (Sweden)

    Louis Thébaud

    2015-11-01

    Full Text Available High temperature creep and dwell-fatigue properties of the new nickel-based superalloy AD730™ have been investigated. Three microstructures have been studied in creep (850 °C and 700 °C and dwell-fatigue (700 °C stress control with trapezoidal signals, and dwell times ranging from 1 s to 3600 s: a coarse grains microstructure, a fine grains one, and single crystalline samples. The aim of this study is to assess the influence of the grain size on creep and creep-fatigue properties. It is demonstrated that fine and coarse grains microstructures perform similarly in creep at 700 °C, showing that the creep properties at this temperature are controlled by the intragranular precipitation. Moreover, both the coarse grains and the fine grains microstructures show changes in creep deformation mechanisms depending on the applied stress in creep at 700 °C. At higher creep temperatures, the coarse grains microstructure performs better and almost no effect is observed by suppressing grain boundaries. During dwell-fatigue tests at 700 °C, a clear effect of the mechanical cycling has been evidenced on the time to failure on both the coarse and the fine grains microstructures. At high applied stresses, a beneficial effect of the cyclic unloading to the lifetime has been observed whereas at lower applied stresses, mechanical cycling is detrimental compared to the pure creep lifetime due to the development of a fatigue damage. Complex creep-fatigue interactions are hence clearly evidenced and they depend on the pure creep behavior reference.

  16. A Comparison of Residual Stress Development in Inertia Friction Welded Fine Grain and Coarse Grain Nickel-Base Superalloy

    Science.gov (United States)

    Iqbal, N.; Rolph, J.; Moat, R.; Hughes, D.; Hofmann, M.; Kelleher, J.; Baxter, G.; Withers, P. J.; Preuss, M.

    2011-12-01

    The effect of the base material microstructure on the development of residual stresses across the weld line in inertia friction welds (IFWs) of high-strength nickel-base superalloy RR1000 was studied using neutron diffraction. A comparison was carried out between tubular IFW specimens generated from RR1000 heat treated below (fine grain (FG) structure) and above (coarse grain (CG) structure) the γ'-solvus. Residual stresses were mapped in the as-welded (AW) condition and, after a postweld heat treatment (PWHT), optimized for maximum alloy strength. The highest tensile stresses were generally found in the hoop direction at the weld line near the inner diameter of the tubular-shaped specimens. A comparison between the residual stresses generated in FG and CG RR1000 suggests that the starting microstructure has little influence on the maximum residual stresses generated in the weld even though different levels of energy must be input to achieve a successful weld in each case. The residual stresses in the postweld heat treated samples were about 35 pct less than for the AW condition. Despite the fact that the high-temperature properties of the two parent microstructures are different, no significant differences in terms of stress relief were found between the FG and CG RR1000 IFWs. Since the actual weld microstructures of FG and CG RR1000 inertia welds are very similar, the results suggest that it is the weld microstructure and its associated high-temperature properties rather than the parent material that affects the overall weld stress distribution and its subsequent stress relief.

  17. Hot Corrosion Behaviour of Detonation Gun Sprayed Al2O3-40TiO2 Coating on Nickel Based Superalloys at 900°C

    Directory of Open Access Journals (Sweden)

    N. K. Mishra

    2014-01-01

    Full Text Available Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. These failures occur because of the usage of wide range of fuels such as, coal and oil at the elevated temperatures. Nickel based superalloys having excellent mechanical strength and creep resistance at elevated temperature are used under such environment but they lack resistance to hot corrosion at high temperature. To overcome these problems hot corrosion resistant coatings are deposited on these materials. In the current investigation Al2O3-40%TiO2 powder has been deposited on Superni 718 and AE 435 superalloys by Detonation Gun method. The hot corrosion performance of Al2O3-40%TiO2 coated as well as uncoated Superni 718 and AE 435 alloys has been evaluated in aggressive environment Na2SO4-82%Fe2(SO43 under cyclic conditions at an elevated temperature of 900°C. The kinetics of the corrosion is approximated by weight change measurements made after each cycle for total duration of 50 cycles. Scanning electron microscopy was used to characterize the hot corrosion products. The coated samples imparted better hot corrosion resistance than the uncoated ones. The AE 435 superalloy performed better than Superni 718 for hot corrosion in a given environment.

  18. Multiscale modelling and simulation of single crystal superalloy turbine blade casting during directional solidiifcation process

    Institute of Scientific and Technical Information of China (English)

    Xu Qingyan; Zhang Hang; Liu Baicheng

    2014-01-01

    As the key parts of an aero-engine, single crystal (SX) superalloy turbine blades have been the focus of much attention. However, casting defects often occur during the manufacturing process of the SX turbine blades. Modeling and simulation technology can help to optimize the manufacturing process of SX blades. Multiscale coupled models were proposed and used to simulate the physical phenomena occurring during the directional solidification (DS) process. Coupled with heat transfer (macroscale) and grain growth (meso-scale), 3D dendritic grain growth was calculated to show the competitive grain growth at micro-scale. SX grain selection behavior was studied by the simulation and experiments. The results show that the geometrical structure and technical parameters had strong inlfuences on the grain selection effectiveness. Based on the coupled models, heat transfer, grain growth and microstructure evolution of a complex holow SX blade were simulated. Both the simulated and experimental results show that the stray grain occurred at the platform of the SX blade when a constant withdrawal rate was used in manufacturing process. In order to avoid the formation of the stray crystal, the multi-scale coupled models and the withdrawal rate optimized technique were applied to the same SX turbine blade. The modeling results indicated that the optimized variable withdrawal rate can achieve SX blade castings with no stray grains, which was also proved by the experiments.

  19. Multiscale modelling and simulation of single crystal superalloy turbine blade casting during directional solidification process

    Directory of Open Access Journals (Sweden)

    Xu Qingyan

    2014-07-01

    Full Text Available As the key parts of an aero-engine, single crystal (SX superalloy turbine blades have been the focus of much attention. However, casting defects often occur during the manufacturing process of the SX turbine blades. Modeling and simulation technology can help to optimize the manufacturing process of SX blades. Multiscale coupled models were proposed and used to simulate the physical phenomena occurring during the directional solidification (DS process. Coupled with heat transfer (macroscale and grain growth (meso-scale, 3D dendritic grain growth was calculated to show the competitive grain growth at micro-scale. SX grain selection behavior was studied by the simulation and experiments. The results show that the geometrical structure and technical parameters had strong influences on the grain selection effectiveness. Based on the coupled models, heat transfer, grain growth and microstructure evolution of a complex hollow SX blade were simulated. Both the simulated and experimental results show that the stray grain occurred at the platform of the SX blade when a constant withdrawal rate was used in manufacturing process. In order to avoid the formation of the stray crystal, the multi-scale coupled models and the withdrawal rate optimized technique were applied to the same SX turbine blade. The modeling results indicated that the optimized variable withdrawal rate can achieve SX blade castings with no stray grains, which was also proved by the experiments.

  20. Evolution of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

    Institute of Scientific and Technical Information of China (English)

    Xiangbin Meng; Jinguo Li; Tao Jin; Xiaofeng Sun; Changbo Sun; Zhuangqi Hu

    2011-01-01

    The process of grain selection in the spiral selector was investigated by both a ProCAST simulation based on a cellular automaton finite element (CAFE) model and experimental confirmation. The results show that the height of starter block, the spiral diameter and initial angle play an important role in grain selection. The dimension of selector should be maintained in a stable range to optimize the grain orientation and select a single crystal efficiently. A selector which can efficiently select a single crystal had been successfully designed. Grain orientation fluctuation in the spiral part was also studied by means of the variation of thermal condition.

  1. Characterization and Modeling of Residual Stress and Cold Work Evolution in PM Nickel Base Disk Superalloy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Powder metal (PM) superalloys used for critical compressor and turbine disk applications are prone to fatigue failures in stress concentration features such as holes...

  2. Crevice corrosion of nickel superalloy in deaerated chloride/sulphate solution at 90°C

    Science.gov (United States)

    Rincón Ortiz, M.; Carranza, R. M.; Rodríguez, M. A.

    2017-01-01

    Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. It was designed to resist to most aggressive environments for industrial applications. Electrochemical studies such as Potentiodynamic-Galvanostatic-Potentiostatic (PD-GS-PD) tests and Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscopy (SEM) observations were performed to determine the corrosion behaviour of alloy 22 (N06022). The effect of sulphate ion in chloride containing solutions at 90°C, were studied in this work under aggressive conditions where this material might be susceptible to crevice corrosion. The electrolyte solution, which consisted of 0.1M and 1M NaCl and different sulphate concentrations. It was observed that there were complete inhibitions of crevice corrosion for R crit =[SO4 =]/[Cl-]=1 in the 0.1mol/L NaCl solutions and R crit =2 in the 1mol/L NaCl solutions. The corrosion rate obtained was about 0.1μm/year at 24 hours of immersion.

  3. CO2 laser cut quality of Inconel 718 nickel - based superalloy

    Science.gov (United States)

    Hasçalık, Ahmet; Ay, Mustafa

    2013-06-01

    This paper experimentally investigates the cut quality of laser cutting for the age hardened Inconel 718 nickel based super alloy, with the use of a continuous CO2 4.0 kW laser cutting system. The quality of the cut has been monitored by measuring the kerf taper ratio, the recast layer thickness and the surface roughness of the cut specimens. The effects of processing parameters, such as the laser power, the cutting speed and the assisting gas pressure were evaluated. Scanning electron microscopy (SEM), Energy Dispersive Spectrography (EDS), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and Knoop hardness tests are carried out to examine the cutting defects, the kerf size variation and formed carbide on the surfaces. A statistical analysis of the results has been performed in order for the effect of each parameter on the cutting quality to be determined. The regression analysis has been used for the development of empirical models able to describe the effect of the process parameters on the quality of laser cutting.

  4. Creep deformation behaviour of Rhenium free Ni-based single crystal superalloys LSC-15

    Directory of Open Access Journals (Sweden)

    Tsuno Nobuyasu

    2014-01-01

    Full Text Available In this paper, creep deformation behavior of Ni-based single crystal superalloys LSC-15 were studied. LSC-15 does not include Rhenium and has been developed by IHI Corporation Japan. Creep tests were performed at 1000 and 1050 ∘C under several stress levels. The creep deformation behaviour was different between test temperatures at 1000 ∘C and 1050 ∘C. Moreover, the relationship between the minimum creep rate and stress was different at the various temperatures. The stress exponent values at 1000 ∘C and 1050 ∘C, were n = 6 and 12 respectively. This difference was due to differences in the formation of dislocation network. At 1000 ∘C, when the minimum creep rate, the dislocation network formed completely independent of stress level. On the other hand, at 1050 ∘C, the dislocation network had not developed fully at the minimum creep rate and the formation of dislocation network depended on the stress level. Therefore, stress dependency at 1050 ∘C is higher than that at 1000 ∘C.

  5. Numerical Simulation and Optimization of Directional Solidification Process of Single Crystal Superalloy Casting

    Directory of Open Access Journals (Sweden)

    Hang Zhang

    2014-02-01

    Full Text Available The rapid development of numerical modeling techniques has led to more accurate results in modeling metal solidification processes. In this study, the cellular automaton-finite difference (CA-FD method was used to simulate the directional solidification (DS process of single crystal (SX superalloy blade samples. Experiments were carried out to validate the simulation results. Meanwhile, an intelligent model based on fuzzy control theory was built to optimize the complicate DS process. Several key parameters, such as mushy zone width and temperature difference at the cast-mold interface, were recognized as the input variables. The input variables were functioned with the multivariable fuzzy rule to get the output adjustment of withdrawal rate (v (a key technological parameter. The multivariable fuzzy rule was built, based on the structure feature of casting, such as the relationship between section area, and the delay time of the temperature change response by changing v, and the professional experience of the operator as well. Then, the fuzzy controlling model coupled with CA-FD method could be used to optimize v in real-time during the manufacturing process. The optimized process was proven to be more flexible and adaptive for a steady and stray-grain free DS process.

  6. Influence of Processing Parameters on the Solidification Behavior of Single-Crystal CMSX-4 Superalloy

    Science.gov (United States)

    Wang, Fu; Ma, Dexin; Bogner, Samuel; Bührig-Polaczek, Andreas

    2016-07-01

    The microstructural evolution of a superalloy, single-crystal CMSX-4 solidified at different withdrawal rates was investigated using a directional solidification quenching method. Analyses of the cross-sections within mushy zones generated the evolution of the solid volume fractions ( f s) during the reduction in the temperature and the solidification sequences. At the withdrawal rate of 0.3 mm min-1, f s increases by about 81 pct within the first 23 pct of the solidification interval, whereas it increases by about 64 pct at the withdrawal rate of 0.7 mm min-1. The Bower-Brody-Flemings model can characterize the evolution tendency of f s curve at the lower withdrawal rate, while it can not only describe the changing tendency of f s, but also precisely predict the f s values at higher withdrawal rate. With increasing withdrawal rate, the solidification intervals of the γ dendrite and γ/ γ' eutectics are increased. In addition to this, the forming site of the γ/ γ' eutectic at the lower withdrawal rate lags behind that at the higher withdrawal rate. At both the withdrawal rates the solidification of the γ/ γ' eutectic islands commences with the γ/ γ' core formed on the surface of the γ dendrites, then progressed spatially and developed the coarse γ/ γ' structure.

  7. Dynamics of micromechanisms controlling the mechanical behaviour of industrial single crystal superalloys

    Indian Academy of Sciences (India)

    M Benyoucef; A Coujou; F Pettinari-Sturmel; S Raujol; B Boubker; N Clément

    2003-02-01

    When deforming bulk material, micromechanisms involving moving defects result in mechanical characteristics observed at a macroscopic scale. In situ straining of microsamples in a Transmission Electron Microscope. provides the unique advantage of observing the dislocation dynamics involved in such microdeformation processes under the combined effects of stress and temperature. Here the efficiency of this technique is illustrated by describing the different obstacles controlling the movement of dislocations in a two-phase industrial single crystal superalloy. At 25° and 850°C, different core structures of the moving dislocations as well as several ways of crossing obstacles are described, which concern the movement of dislocations in channels, at $\\gamma /\\gamma' $ interfaces and while shearing $\\gamma' $ precipitates. From these observations, a quantitative analysis is developed leading to the evaluation of the critical propagation stresses involved in the channels of the matrix and when crossing the interfaces. This allows to discuss the various sites of resistance opposed to the dislocation movements and controlling the macroscopic deformation.

  8. Creep lifing methodologies applied to a single crystal superalloy by use of small scale test techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jeffs, S.P., E-mail: s.p.jeffs@swansea.ac.uk [Institute of Structural Materials, Swansea University, Singleton Park SA2 8PP (United Kingdom); Lancaster, R.J. [Institute of Structural Materials, Swansea University, Singleton Park SA2 8PP (United Kingdom); Garcia, T.E. [IUTA (University Institute of Industrial Technology of Asturias), University of Oviedo, Edificio Departamental Oeste 7.1.17, Campus Universitario, 33203 Gijón (Spain)

    2015-06-11

    In recent years, advances in creep data interpretation have been achieved either by modified Monkman–Grant relationships or through the more contemporary Wilshire equations, which offer the opportunity of predicting long term behaviour extrapolated from short term results. Long term lifing techniques prove extremely useful in creep dominated applications, such as in the power generation industry and in particular nuclear where large static loads are applied, equally a reduction in lead time for new alloy implementation within the industry is critical. The latter requirement brings about the utilisation of the small punch (SP) creep test, a widely recognised approach for obtaining useful mechanical property information from limited material volumes, as is typically the case with novel alloy development and for any in-situ mechanical testing that may be required. The ability to correlate SP creep results with uniaxial data is vital when considering the benefits of the technique. As such an equation has been developed, known as the k{sub SP} method, which has been proven to be an effective tool across several material systems. The current work now explores the application of the aforementioned empirical approaches to correlate small punch creep data obtained on a single crystal superalloy over a range of elevated temperatures. Finite element modelling through ABAQUS software based on the uniaxial creep data has also been implemented to characterise the SP deformation and help corroborate the experimental results.

  9. Oxide-assisted crack growth in hold-time low-cycle-fatigue of single-crystal superalloys

    Directory of Open Access Journals (Sweden)

    Suzuki Akane

    2014-01-01

    Full Text Available Compressive hold-time low-cycle fatigue is one of the important damage modes in Ni-based superalloy hot-gas path components. In strain controlled LCF, the compressive hold typically degrades fatigue life significantly due to creep relaxation and the resultant generation of tensile stress upon returning to zero strain. Crack initiation typically occurs on the surface, and therefore, the cracks are covered with layers of oxides. Recent finite element modeling based on experimental observations has indicated that the in-plane compressive stress in the alumina layer formed on the surface of the bond coat assists rumpling and, eventually, leads to initiation of cracks. The stress in the oxide layer continues to assist crack extension by pushing the alumina layer along the crack front during the compressive hold. In-situ measurements of the growth strains of alumina were performed using high energy synchrotron X-rays at Argonne National Lab. Specimens of single-crystal superalloys with and without aluminide coatings were statically pre-oxidized to form a layer of alumina at 1093 and 982 ∘C. For the in-situ synchrotron measurements, the specimens were heated up to the pre-oxidation temperatures with a heater. The alumina layers on both bare and coated specimens show compressive in-plane strains at both temperatures. The oxide strains on the superalloys showed dependency on temperature; on the other hand, the oxide strains in the aluminide coatings were insensitive to temperature. The magnitude of the compressive strains was larger on the superalloys than the ones on the aluminide coatings.

  10. Surface recrystallization of a Ni_3Al based single crystal superalloy at different annealing temperatures and blasting pressure

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effects of annealing temperature and grit blasting pressure on the recrystallization behavior of a Ni3Al based single crystal superalloy were studied in this work. The results show that the precipitation of the Y-NiMo phase occurs at 900 and 1000 °C, which precedes recrystallization. The initial recrystallization temperature was between 1000 and 1100 °C. Cellular recrystallization was formed at 1100 and 1200 °C, which consisted of large columnar γ′ and fine γ + γ′. The dendrite arm closed to the interde...

  11. Low cycle fatigue and creep-fatigue interaction behavior of nickel-base superalloy GH4169 at elevated temperature of 650 °C

    Energy Technology Data Exchange (ETDEWEB)

    Chen, G., E-mail: agang@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhang, Y. [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Xu, D.K. [Environmental Corrosion Center, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Lin, Y.C. [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); Chen, X. [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2016-02-08

    Total strain-controlled low cycle fatigue (LCF) tests of a nickel based superalloy were performed at 650 °C. Various hold times were introduced at the peak tensile strain to investigate the high-temperature creep-fatigue interaction (CFI) effects under the same temperature. A substantial decrease in fatigue life occurred as the total strain amplitude increased. Moreover, tensile strain holding further reduced fatigue life. The saturation phenomenon of holding effect was found when the holding period reached 120 s. Cyclic softening occurred during the LCF and CFI process and it was related to the total strain amplitude and the holding period. The relationship between life-time and total strain amplitude was obtained by combining Basquin equation and Coffin-Manson equation. The surface and fracture section of the fatigued specimens were observed via scanning electronic microscope (SEM) to determine the failure mechanism.

  12. The effects of tantalum on the microstructure of two polycrystalline nickel-base superalloys - B-1900 + Hf and MAR-M247

    Science.gov (United States)

    Heckel, R. W.; Pletka, B. J.; Janowski, G. M.

    1986-01-01

    The effect of changing the content of Ta on the gamma/gamma-prime carbide microstructure was investigated in two crystalline nickel-base superalloys: conventionally cast B-1900 + Hf, and both conventionally cast and directionally solidified MAR-M247. The changes occurring in the microstructure effects were similar in both alloys. The gamma-prime and carbide volume fractions increased linearly with Ta additions, while the gamma-prime phase compositions did not change. Bulk Ta additions increased the levels of Cr and Co (in addition to that of Ta) of the gamma phase, a result of the approximately constant partitioning ratios for these two elements. The addition of Ta led to a partial replacement of Hf in the MC carbides. In addition, Cr-rich M(23)C(6) carbides formed as a result of MC carbide decomposition during heat treatment.

  13. Effect of residual elements on high performance nickel base superalloys for gas turbines and strategies for manufacture

    Indian Academy of Sciences (India)

    O P Sinha; M Chatterjee; V V R S Sarma; S N Jha

    2005-07-01

    The need for better gas turbine operating efficiency and reliability has resulted in tightening of specification and acceptance standards. It has been realized that some elements even at trace level, can have disastrous effect on high temperature properties. The present paper highlights the adverse effect of tramp elements and strategies that should be adopted to produce high purity superalloys.

  14. Improvement of the Oxidation Resistance of the Single-Crystal Ni-Based TMS-82+ Superalloy by Ni–Al Coatings with/without the Diffusion Barrier

    NARCIS (Netherlands)

    Wu, Y.; Li, X.W.; Song, G.M.; Wang, Y.M.; Narita, T.

    2010-01-01

    Oxidation behavior of the uncoated base, Ni–Al coated and Re–Cr-Ni plus Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy is studied under cyclic air at 900ºC for 200 h to assess the oxidation resistance. Regardless of the coating processing, Ni–Al coating is effective in improving the ox

  15. Cube slip and non-Schmid effects in single crystal Ni-base superalloys

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2010-01-01

    An advanced constitutive model incorporating two specific aspects of Ni-base superalloy deformation behaviour is proposed. Several deformation mechanisms are active in these two-phase materials. In the matrix phase, cube slip plays an important role in the orientation dependence of the material. Mor

  16. Oxidation behavior and mechanism of powder metallurgy Rene95 nickel based superalloy between 800 and 1000 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Lei, E-mail: zhenglei_ustb@sina.com [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 10083 (China); Zhang Maicang; Dong Jianxin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 10083 (China)

    2010-10-01

    The oxidation behaviors of powder metallurgy (PM) Rene95 Ni-based superalloy in the temperature range of 800-1000 deg. C are investigated in air by virtue of isothermal oxidation testing, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that the oxidation kinetics follows a square power law as the time extends at each temperature. The oxidation layers are detected to be composed of Cr{sub 2}O{sub 3}, TiO{sub 2} and a small amount of NiCr{sub 2}O{sub 4}. The cross-sectional morphologies indicate that the oxidation layer consists of three parts: Cr-rich oxide layer, Cr and Ti duplex oxide layer, and oxidation affected zone. Theoretical analyses of oxidation kinetics and thicknesses of oxidation layers confirm that the activation energy of oxidation of PM Rene95 superalloy is 165.32 kJ mol{sup -1} and the oxidation process is controlled by diffusions of oxygen, Cr, and Ti. Accordingly, a diffusion-controlled mechanism is suggested to understand the oxidation behaviors of PM Rene95 superalloy at elevated temperatures.

  17. Improvement of the Oxidation Resistance of the Single-Crystal Ni-Based TMS-82+ Superalloy by Ni–Al Coatings with/without the Diffusion Barrier

    OpenAIRE

    Wu, Y.; Li, X. W.; Song, G.M.; Wang, Y. M.; Narita, T.

    2010-01-01

    Oxidation behavior of the uncoated base, Ni–Al coated and Re–Cr-Ni plus Ni–Al coated single-crystal (SC) Ni-based TMS-82+ superalloy is studied under cyclic air at 900ºC for 200 h to assess the oxidation resistance. Regardless of the coating processing, Ni–Al coating is effective in improving the oxidation resistance due to the formation of a continuous a-Al2O3 layer in the scale. For the uncoated base superalloy, the mass-gain curves are fitted by a subparabolic relationship, and complex oxi...

  18. SUPERALLOYS: AN INTRODUCTION WITH THERMAL ANALYSIS ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... another precipitation strengthened nickel base superalloy, has a very good strength at ... Keywords: Superalloys; Phase reactions; Differential Thermal Analysis; Latent heat of ... high-temperature strength and creep resistance. ... Borides, a relatively low density of boride particles formed when boron ...

  19. Alloy Design Challenge: Development of Low Density Superalloys for Turbine Blade Applications

    Science.gov (United States)

    MacKay, Rebecca A.; Gabb, Timothy P.; Smialek, James L.; Nathal, Michael V.

    2009-01-01

    New low density single crystal (LDS) alloys have been developed for turbine blade applications, which have the potential for significant improvements in the thrust to weight ratio over current production alloys. An innovative alloying strategy was identified to achieve high temperature creep resistance, alloy density reductions, microstructural stability, and cyclic oxidation resistance. The approach relies on the use of molybdenum (Mo) as a potent solid solution strengthener for the nickel (Ni)-base superalloy; Mo has a density much closer to Ni than other refractory elements, such as rhenium (Re) or tungsten (W). A host of testing and microstructural examinations was conducted on the superalloy single crystals, including creep rupture testing, microstructural stability, cyclic oxidation, and hot corrosion. The paper will provide an overview of the single crystal properties that were generated in this new superalloy design space. The paper will also demonstrate the feasibility of this innovative approach of low density single crystal superalloy design. It will be shown that the best LDS alloy possesses the best attributes of three generations of single crystal alloys: the low density of first-generation single crystal alloys, the excellent oxidation resistance of second-generation single crystal alloys, and a creep strength which exceeds that of second and third generation alloys.

  20. Experimental Study on Burrs in Micro-milling Nickel-base Superalloy Inconel718%镍基高温合金Inconel718微铣削毛刺试验研究∗

    Institute of Scientific and Technical Information of China (English)

    卢晓红; 武文毅; 王文韬; 裴兴林; 路彦君; 司立坤

    2015-01-01

    基于微小型机床的微铣削( Micro-milling )技术是加工镍基高温合金微小结构/零件的可行技术手段。文章通过镍基高温合金微铣削加工实验,利用扫描电子显微镜和能谱分析仪对刀具的磨、破损形态及局部化学成分和槽的表面形貌进行了研究分析,发现镍基高温合金微铣削毛刺形貌及成因与镍基高温合金传统切削或其他材料微铣削具有很大不同:首先,毛刺长度过长;其次,刀具磨损对鳞刺的产生有很大影响;鳞刺只出现在槽的一侧边界。在实验研究基础上,分析了毛刺的成因,为后续镍基高温合金微铣削毛刺的有效抑制研究提供参考。%Micro milling technology which is based on the micro machine tool is one of the feasible skills processing the Nickel-based superalloy micro constructions/parts. Micro-milling Nickel-based superalloy tests have been carried out and then the wear/break features and the chemical component of the testing tool as well as the surface features of the testing slots have been researched. Results show that the burrs’ features and causes in micro milling Nickel-based superalloy have great differences from the traditionally milling Nickel-based superalloy and micro milling other materials. Firstly, the length of the burrs is too long. Sec-ondly, tool wearing has great effects on the scales’ formation. Thirdly, the scales only appear on the one side of the testing slots. Based on the tests and researches, formation of the burrs has been studied to provide references for controlling the burrs in micro milling Nickel-based superalloy effectively.

  1. Study of phase transformations in CMSX-6 and CMSX-8 superalloys

    Science.gov (United States)

    Szczotok, Agnieszka; Wierzbicka-Miernik, Anna

    2014-09-01

    Nickel-based superalloys are extensively used mainly in the aircraft and aeronautic industry, particularly in the hottest parts of engines or turbo-reactors. The phase reactions occurring in these heat-resistant materials play a crucial role in many aspects of the processing and service of the highly alloyed materials. Cast Ni-based superalloys are obtained in a complex way and their structure is complicated. Differential scanning calorimetry (DSC) technique was applied for determination of temperature ranges of the phase transformations occurring in the CMSX-6 and CMSX-8 superalloys during heating/cooling processes. Thermophysical properties, including temperatures of the phase transformation, are the critical input parameters in mathematical models of solidification and casting of metallic materials. The literature data concerning phase transformations and performance of the heat treatment for CMSX-6 and CMSX-8 are incomplete and ambiguous. DSC results accompanied by scanning electron microscopy characterization of microstructure of CMSX-6 and CMSX-8 superalloy was applied. The present study will improve the understanding of the fundamental mechanisms of phase transformations of single-crystal nickel-based superalloys.

  2. Electrodeposition on Superalloy Substrates: a Review

    Science.gov (United States)

    Allahyarzadeh, M. H.; Aliofkhazraei, M.; Rouhaghdam, A. Sabour

    2016-02-01

    The present paper reviews various types of coatings, including platinum, platinum alloys, palladium, ruthenium, iridium, nickel, nickel alloys and composite coatings, on superalloy substrates using electrodeposition method. Attempts were carried out to represent an overall view of plating conditions and electrolyte and highlight the importance of the layer regarding to the performance of high-temperature coatings applied on superalloys, which is extensively used on gas-turbine components.

  3. Effect of solidification parameters on the microstructures of a single crystal Ni-based superalloy AM3

    Institute of Scientific and Technical Information of China (English)

    Yu Zhuhuan; Liu Lin; Zhao Xinbao; Zhang Weiguo; Zhang Jun; Fu Hengzhi

    2010-01-01

    A single crystal Ni-based superalloy AM3 was processed at withdraw rates of 3.5, 10, 50, 100, 200, and 500 IJm-s-1, respectively. The as-cast microstructures and solidification segregation ratio were characterized with various withdraw rates. The shape and size of carbide microstructuras were determined. As expected, the primary and secondary dendrite arm spacings (PDAS and SDAS) decrease with the increase of withdraw rate. The highest volume fraction of eutectic γ/γ' is observed at the 100 μm·s-1 withdraw rate. The volume fraction of eutectic γ/γ' does not appear to be a strong function of the withdraw rate. With increasing withdraw rate, interface morphologies change in the sequence of planar, cellular, and dendrite. There is a general refinement of the microstructure as the withdraw rate increases. EPMA analysis showed that withdraw rate does not have obvious influence on the segregation of elements.

  4. The influence of cobalt on the tensile and stress-rupture properties of the nickel-base superalloy mar-m247

    Science.gov (United States)

    Nathal, M. V.; Maier, R. D.; Ebert, L. J.

    1982-10-01

    The influence of cobalt on the mechanical properties of MAR-M247, a cast nickel-base superalloy, was investigated. Nickel was substituted for cobalt to produce 0, 5, and the standard 10 pct cobalt versions of MAR-M247. Tensile tests were performed between 649 and 982 dgC; stress-rupture tests were conducted at temperatures ranging from 760 to 982 dgC. The tensile properties were not significantly affected by cobalt level, but a slight peak in strength at 5 pct Co was apparent. A -80 °C shift in the peak yield strength temperature as Co level was reduced from 10 to 0 pct was also evident. This behavior was related to a reduction in the γ' volume fraction, an increase in γ' particle size, an increase in W and Ti concentrations in the γ', and a decrease in Cr and Al concentrations in the γ as Co level in MAR-M247 was reduced. Stress-rupture properties, however, were more significantly affected by Co level. The 10 pct Co alloy exhibited rupture lives typically 1.2 times greater than that of the 5 pct Co alloy and 3 times greater than that of the 0 pct Co alloy. The steady state creep rate of the 10 pct Co alloy was generally equal to that of the 5 pct Co alloy, but was only one third as large as the creep rate of the 0 pct Co alloy. This behavior was associated with a decrease in γ' volume fraction and the formation of a grain boundary carbide film as cobalt level was reduced.

  5. Thermal analysis of silicon carbide coating on a nickel based superalloy substrate and thickness measurement of top layers by lock-in infrared thermography

    Energy Technology Data Exchange (ETDEWEB)

    Ranjit, Shrestha; Kim, Won Tae [Kongju National University, Cheonan (Korea, Republic of)

    2017-04-15

    In this paper, we investigate the capacity of the lock-in infrared thermography technique for the evaluation of non-uniform top layers of a silicon carbide coating with a nickel based superalloy sample. The method utilized a multilayer heat transfer model to analyze the surface temperature response. The modelling of the sample was done in ANSYS. The sample consists of three layers, namely, the metal substrate, bond coat and top coat. A sinusoidal heating at different excitation frequencies was imposed upon the top layer of the sample according to the experimental procedures. The thermal response of the excited surface was recorded, and the phase angle image was computed by Fourier transform using the image processing software, MATLAB and Thermofit Pro. The correlation between the coating thickness and phase angle was established for each excitation frequency. The most appropriate excitation frequency was found to be 0.05 Hz. The method demonstrated potential in the evaluation of coating thickness and it was successfully applied to measure the non-uniform top layers ranging from 0.05 mm to 1 mm with an accuracy of 0.000002 mm to 0.045 mm.

  6. Laser Engineered Net Shaping of Nickel-Based Superalloy Inconel 718 Powders onto AISI 4140 Alloy Steel Substrates: Interface Bond and Fracture Failure Mechanism.

    Science.gov (United States)

    Kim, Hoyeol; Cong, Weilong; Zhang, Hong-Chao; Liu, Zhichao

    2017-03-25

    As a prospective candidate material for surface coating and repair applications, nickel-based superalloy Inconel 718 (IN718) was deposited on American Iron and Steel Institute (AISI) 4140 alloy steel substrate by laser engineered net shaping (LENS) to investigate the compatibility between two dissimilar materials with a focus on interface bonding and fracture behavior of the hybrid specimens. The results show that the interface between the two dissimilar materials exhibits good metallurgical bonding. Through the tensile test, all the fractures occurred in the as-deposited IN718 section rather than the interface or the substrate, implying that the as-deposited interlayer bond strength is weaker than the interfacial bond strength. From the fractography using scanning electron microscopy (SEM) and energy disperse X-ray spectrometry (EDS), three major factors affecting the tensile fracture failure of the as-deposited part are (i) metallurgical defects such as incompletely melted powder particles, lack-of-fusion porosity, and micropores; (ii) elemental segregation and Laves phase, and (iii) oxide formation. The fracture failure mechanism is a combination of all these factors which are detrimental to the mechanical properties and structural integrity by causing premature fracture failure of the as-deposited IN718.

  7. The Effect of Boron and Zirconium on Microstructure and Stress-Rupture Life of Nickel-based Superalloy ATI 718Plus

    Directory of Open Access Journals (Sweden)

    Seyed Ali Hosseini

    2015-12-01

    Full Text Available The effects of boron and zirconium on the microstructure, hardness and stressrupture life of the nickel-based superalloy ATI 718Plus were investigated in this study. Four alloys with different percentages of boron (0.005-0.01 wt.% and zirconium (0-0.1 wt% were cast through a vacuum induction melting furnace and then were rolled. The microstructural studies indicated an increased percentage of δ phase, carbide precipitates and twins in the presence of zirconium. The percentage of carbide (boron carbide precipitates was increased and the solidification range of the alloy was decreased in the presence of boron in the composition. Furthermore, the results obtained from the hardness and stress-rupture tests showed the significant role of both elements in increasing hardness and improved rupture life of the alloy. The maximum rupture life was observed in the alloy which contained the highest percentages of boron and zirconium in its composition. This can be attributed mainly to the increased percentage of δ phase on grain boundaries and their enhanced high-temperature strength.

  8. The effects of tantalum on the microstructure of two polycrystalline nickel-base superalloys: B-1900 + Hf and MAR-M247

    Science.gov (United States)

    Janowski, G. M.; Heckel, R. W.; Pletka, B. J.

    1986-11-01

    Changes in the γ/γ'/carbide microstructure as a function of Ta content were studied in conventionally cast B-1900 + Hf and both conventionally cast and directionally solidified MAR-M247.* The effects of tantalum on the microstructure were found to be similar in both nickel-base superalloys. In particular, the γ' and carbide volume fractions increased approximately linearly with tantalum additions in both alloys. The γ' phase compositions did not change as tantalum additions were made with the exception of an increase in the tantalum level. Bulk tantalum additions increased the tantalum, chromium, and cobalt levels of the γ phase in both alloy series. The increase in the concentrations of the latter two elements was attributed to a decrease in the γ phase fraction with increasing bulk tantalum level and nearly constant γ' /γ partitioning ratios. It was demonstrated that the large increase in the γ ' volume fraction was a result of tantalum not affecting the partitioning ratios of the other alloying elements. The addition of tantalum led to a partial replacement of the hafnium in the MC carbides, although the degree of replacement was reduced by the solutionizing and aging heat treat-ment. In addition, chromium-rich M23C6 carbides formed as a result of MC carbide decomposition during heat treatment.

  9. Modeling Long-term Creep Performance for Welded Nickel-base Superalloy Structures for Power Generation Systems

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen

    2015-01-01

    We report here a constitutive model for predicting long-term creep strain evolution in’ strengthened Ni-base superalloys. Dislocation climb-bypassing’, typical in intermediate’ volume fraction (~20%) alloys, is considered as the primary deformation mechanism. Dislocation shearing’ to anti-phase boundary (APB) faults and diffusional creep are also considered for high-stress and high-temperature low-stress conditions, respectively. Additional damage mechanism is taken into account for rapid increase in tertiary creep strain. The model has been applied to Alloy 282, and calibrated in a temperature range of 1375-1450°F, and stress range of 15-45ksi. The model parameters and a MATLAB code are provided. This report is prepared by Monica Soare and Chen Shen at GE Global Research. Technical discussions with Dr. Vito Cedro are greatly appreciated. This work was supported by DOE program DE-FE0005859

  10. Characterization and modeling of quenching-induced residual stresses in the nickel-based superalloy IN718

    Science.gov (United States)

    Dye, D.; Conlon, K. T.; Reed, R. C.

    2004-06-01

    The residual stress fields in pieces of quenched IN718 superalloy have been characterized by neutron diffraction. The samples were in the form of cylindrical rods of length sufficient to ensure that steady-state conditions prevail at the midsection. Quenching the samples in air, water, and oil generated various residual stress fields. The interfacial heat-transfer coefficients were estimated using an inverse-modeling technique. The findings were rationalized with an elastic-plastic finite-element model that included temperature-dependent properties. The hoop and axial stresses are the most significant components of the stress field and arise from the plastic deformation occurring at the periphery of the cylindrical sections, the extent of which depends strongly upon the severity of the quench. The model is used to examine the residual stress fields to be expected in a turbine-disc forging of idealized geometry.

  11. The Influence of Impurities in Feed Ingots on the Quality of Castings Made from Nickel Superalloy IN-713C

    Directory of Open Access Journals (Sweden)

    Binczyk F.

    2013-12-01

    Full Text Available The paper presents the results of research on the impact of impurities in the feed ingots (master heat on the precipitation of impurities in the ATD thermal analysis probe castings. This impurities occur mostly inside shrinkage cavities and in interdendritic space. Additionally, insufficient filtration of liquid alloy during pouring promotes the transfer of impurities into the casting. The technology of melting superalloys in vacuum furnace prevents the removal of slag from the surface of molten metal. Because of that, the effective method of quality assessment of feed ingots in order to evaluate the existence of impurities is needed. The effectiveness of ATD analysis in evaluation of purity of feed ingots was researched. In addition the similarities of non-metallic inclusions in feed ingots and in castings were observed.

  12. In- and out-of-phase thermomechanical fatigue of a Ni-based single-crystal superalloy

    Directory of Open Access Journals (Sweden)

    Segersäll Mikael

    2014-01-01

    Full Text Available In this study, the difference between in-phase (IP and out-of-phase (OP thermomechanical fatigue (TMF cycling from 100 to 750 °C has been investigated for the Ni-based single-crystal superalloy MD2. In addition, two different crystal orientations were studied, the ⟨001⟩ and ⟨011⟩ orientations respectively. When comparing IP and OP TMF lives, a strain range dependency is found for the ⟨001⟩ direction. For high strain ranges, IP cycling leads to a higher number of cycles to failure compared to OP. However at lower strain ranges, OP cycling leads to a higher number of cycles to failure compared to IP. Microstructure investigation shows that for the ⟨001⟩ direction, deformation twinning within the γ/γ′-microstructure is much more pronounced during OP conditions compared to IP. However for the ⟨011⟩ direction, the opposite is observed; twinning is more pronounced during IP TMF. From the microstructure investigation it is also visible that intersections between twins seems to trigger formation of TCP phases and recrystallization. These intersections also work as initiation points for TMF damage.

  13. Advanced superalloy airfoils

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M.; Duhl, D.N.; Gupta, D.K.; Sheffler, K.D.

    1987-07-01

    Single-crystal superalloy technology for gas-turbine blades has combined the design of alloys for exclusive use in single-crystal form with advancements in directional solidification, in order to manufacture single-crystal castings with complex internal cooling passages. To these improvements have been incorporated metallic and ceramic coatings that further extend high temperature capabilities. The directional solidification of single-crystal turbine alloys requires total control of the thermal environment, using large vacuum furnaces capable of casting up to 30 blades at a time. All modern coatings involve the enrichment of the superalloy surface with elements that promote the formation and retention of alumina, which precludes further oxidation. 15 references.

  14. The Potential Link Between High Angle Grain Boundary Morphology and Grain Boundary Deformation in a Nickel-Based Superalloy (Postprint)

    Science.gov (United States)

    2015-06-01

    B.V. All rights reserved.1. Introduction The creep deformation in polycrystalline nickel based super alloys is a heterogeneous process, the primary...annealing twins in G1 and G2 (TG1 and TG2 respectively). The d via the offset in hafnium oxide grid lines (white) deposited prior to deformation...titanium alloy , Acta Mater. 58 (16) (2010) 5511–5519 , URL 〈http://journals.ohiolink.edu/ejc/article.cgi? issn 13596454&issue v58i0016&article

  15. Determination of solute site occupancies within γ' precipitates in nickel-base superalloys via orientation-specific atom probe tomography.

    Science.gov (United States)

    Meher, S; Rojhirunsakool, T; Nandwana, P; Tiley, J; Banerjee, R

    2015-12-01

    The analytical limitations in atom probe tomography such as resolving a desired set of atomic planes, for solving complex materials science problems, have been overcome by employing a well-developed unique and reproducible crystallographic technique, involving synergetic coupling of orientation microscopy with atom probe tomography. The crystallographic information in atom probe reconstructions has been utilized to determine the solute site occupancies in Ni-Al-Cr based superalloys accurately. The structural information in atom probe reveals that both Al and Cr occupy the same sub-lattice within the L12-ordered γ' precipitates to form Ni3(Al,Cr) precipitates in a Ni-14Al-7Cr (at%) alloy. Interestingly, the addition of Co, which is a solid solution strengthener, to a Ni-14Al-7Cr alloy results in the partial reversal of Al site occupancy within γ' precipitates to form (Ni,Al)3(Al,Cr,Co) precipitates. This unique evidence of reversal of Al site occupancy, resulting from the introduction of other solutes within the ordered structures, gives insights into the relative energetics of different sub-lattice sites when occupied by different solutes.

  16. The primary creep behavior of single crystal, nickel base superalloys PWA 1480 and PWA 1484

    Science.gov (United States)

    Wilson, Brandon Charles

    Primary creep occurring at intermediate temperatures (650°C to 850°C) and loads greater than 500 MPa has been shown to result in severe creep strain, often exceeding 5-10%, during the first few hours of creep testing. This investigation examines how the addition of rhenium and changes in aging heat treatment affect the primary creep behavior of PWA 1480 and PWA 1484. To aid in the understanding of rhenium's role in primary creep, 3wt% Re was added to PWA 1480 to create a second generation version of PWA 1480. The age heat treatments used for creep testing were either 704°C/24 hr. or 871°C/32hr. All three alloys exhibited the presence of secondary gamma' confirmed by scanning electron microscopy and local electrode atom probe techniques. These aging heat treatments resulted in the reduction of the primary creep strain produced in PWA 1484 from 24% to 16% at 704°C/862 MPa and produced a slight dependence of the tensile properties of PWA 1480 on aging heat treatment temperature. For all test temperatures, the high temperature age resulted in a significant decrease in primary creep behavior of PWA 1484 and a longer lifetime for all but the lowest test temperature. The primary creep behavior of PWA 1480 and PWA 1480+Re did not display any significant dependence on age heat treatment. The creep rupture life of PWA 1480 is greater than PWA 1484 at 704°C, but significantly shorter at 760°C and 815°C. PWA 1480+Re, however, displayed the longest lifetime of all three alloys at both 704°C and 815°C (PWA 1480+Re was not tested at 760°C). Qualitative TEM analysis revealed that PWA 1484 deformed by large dislocation "ribbons" spanning large regions of material. PWA 1480, however, deformed primarily due to matrix dislocations and the creation of interfacial dislocation networks between the gamma and gamma' phases. PWA 1480+ contained stacking faults as well, though they acted on multiple slip systems generating work hardening and forcing the onset of secondary creep. X-ray diffraction and JMatPro calculations were also used to gain insight into the cause of the differences in behaviors.

  17. A study of microstructural characteristics and differential thermal analysis of Ni-based superalloys

    Science.gov (United States)

    Aggarwal, M. D.; Lal, R. B.; Oyekenu, Samuel A.; Parr, Richard; Gentz, Stephen

    1989-01-01

    The objective of this work is to correlate the mechanical properties of the Ni-based superalloy MAR M246(Hf) used in the Space Shuttle Main Engine with its structural characteristics by systematic study of optical photomicrographs and differential thermal analysis. The authors developed a method of predicting the liquidus and solidus temperature of various nickel based superalloys (MAR-M247, Waspaloy, Udimet-41, polycrystalline and single crystals of CMSX-2 and CMSX-3) and comparing the predictions with the experimental differential thermal analysis (DTA) curves using Perkin-Elmer DTA 1700. The method of predicting these temperatures is based on the additive effect of the components dissolved in nickel. The results were compared with the experimental values.

  18. Morphology of {gamma}' precipitates of nickel-based superalloy serviced as first stage high pressure turbine nozzle guide vane

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Nobuhiro; Nakada, Kouji; Kondo, Yoshihiro [National Defense Academy, Yokosuka, Kanagawa (Japan)

    2010-07-01

    The morphology of {gamma}' precipitates of the nickel-based superalloy serviced as the first stage high pressure turbine nozzle guide vane of the jet engine was examined. The aim of this work was to estimate the temperature and the stress distribution, and the stress direction of the vane in service. The vane was cut into four parts perpendicular to the longitudinal direction of the vane at 5, 25, 35 and 45mm from the root. These parts were designated as the root, 25mm, 35mm and tip parts. Microstructure observations by a FE-SEM were carried out on the forty-six portions at the vicinity of the interface between the coating layer and the matrix on the suction and pressure sides. At the root parts of the pressure and suction sides, most of the {gamma}' precipitates kept cuboidal in shape, and the secondary {gamma}' precipitates were observed in the {gamma} matrix channels. On the contrary, at the trailing edge side of the pressure and suction sides of the 25 and 35mm parts and at the leading edge of the pressure side of the tip part, well aligned rafted {gamma}/{gamma}' structures were appeared in the direction parallel to the surface at the vicinity of the interface of the vane. Furthermore, at the trailing edge of the pressure side of the middle parts, the rafted {gamma}/{gamma}' structures start to collapse. Consequently, the vane in service, at the trailing edge sides of the pressure side the 25 and 35mm parts were exposed to the highest temperature and stress conditions. And this microstructure evidence indicated that the multi-axial compressive stress parallel to the nozzle surface was expected to act on the vane in service. (orig.)

  19. On The Creep Behavior and Deformation Mechanisms Found in an Advanced Polycrystalline Nickel-Base Superalloy at High Temperatures

    Science.gov (United States)

    Deutchman, Hallee Zox

    Polycrystalline Ni-base superalloys are used as turbine disks in the hot section in jet engines, placing them in a high temperature and stress environment. As operating temperatures increase in search of better fuel efficiency, it becomes important to understand how these higher temperatures are affecting mechanical behavior and active deformation mechanisms in the substructure. Not only are operating temperatures increasing, but there is a drive to design next generation alloys in shorter time periods using predictive modeling capabilities. This dissertation focuses on mechanical behavior and active deformation mechanisms found in two different advanced polycrystalline alloy systems, information which will then be used to build advanced predictive models to design the next generation of alloys. The first part of this dissertation discusses the creep behavior and identifying active deformation mechanisms in an advanced polycrystalline Ni-based superalloy (ME3) that is currently in operation, but at higher temperatures and stresses than are experienced in current engines. Monotonic creep tests were run at 700°C and between 655-793MPa at 34MPa increments, on two microstructures (called M1 and M2) produced by different heat treatments. All tests were crept to 0.5% plastic strain. Transient temperature and transient stress tests were used determine activation energy and stress exponents of the M1 microstructure. Constant strain rate tests (at 10-4s-1) were performed on both microstructures as well. Following creep testing, both M1 and M2 microstructures were fully characterized using Scanning Electron Microscopy (SEM) for basic microstructure information, and Scanning Transmission Electron Microscopy (STEM) to determine active deformation mechanism. It was found that in the M1 microstructure, reorder mediated activity (such as discontinuous faulting and microtwinning) is dominant at low stresses (655-724 MPa). Dislocations in the gamma matrix, and overall planar

  20. Nickel-disilicide-assisted excimer laser crystallization of amorphous silicon

    Institute of Scientific and Technical Information of China (English)

    Liao Yan-Ping; Shao Xi-Bin; Gao Feng-Li; Luo Wen-Sheng; Wu Yuan; Fu Guo-Zhu; Jing Hai; Ma Kai

    2006-01-01

    Polycrystalline silicon (poly-Si) thin film has been prepared by means of nickel-disilicide (NiSi2) assisted excimer laser crystallization (ELC). The process to prepare a sample includes two steps. One step consists of the formation of NiSi2 precipitates by heat-treating the dehydrogenated amorphous silicon (a-Si) coated with a thin layer of Ni. And the other step consists of the formation of poly-Si grains by means of ELC. According to the test results of scanning electron microscopy (SEM), another grain growth model named two-interface grain growth has been proposed to contrast with the conventional Ni-metal-induced lateral crystallization (Ni-MILC) model and the ELC model. That is, an additional grain growth interface other than that in conventional ELC is formed, which consists of NiSi2 precipitates and a-Si.The processes for grain growth according to various excimer laser energy densities delivered to the a-Si film have been discussed. It is discovered that grains with needle shape and most of a uniform orientation are formed which grow up with NiSi2 precipitates as seeds. The reason for the formation of such grains which are different from that of Ni-MILCwithout migration of Ni atoms is not clear. Our model and analysis point out a method to prepare grains with needle shape and mostly of a uniform orientation. If such grains are utilized to make thin-film transistor, its characteristics may be improved.

  1. Effect of Solidification Condition on Microstructure and Mechanical Properties of Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CMSX-2 single crystals with different primary dendrite arm spacing were obtained on directional solidification apparatus with high temperature gradient (250 K/cm). The microstructure and elevated temperature stress rupture properties of these single crystals were examined and analyzed.

  2. Focused Ion Beam Nanotomography of ruthenium-bearing nickel-base superalloys with focus on cast-microstructure and phase stability; Focused Ion Beam Nanotomographie von rutheniumhaltigen Nickelbasis-Superlegierungen mit Fokus auf Gussgefuege und Phasenstabilitaet

    Energy Technology Data Exchange (ETDEWEB)

    Cenanovic, Samir

    2012-12-03

    The influence of rhenium and ruthenium on the multi component system nickel-base superalloy is manifold and complex. An experimental nickel-base superalloy containing rhenium and ruthenium within defined contents, named Astra, was used to investigate the influences of these two elements on the alloy system. The last stage solidification of nickel-base superalloys after Bridgman casting and the high temperature phase stability of these alloys, could be explored with the aid of focused ion beam nanotomography. FIB-nt therefore was introduced and realized at the chair of General Materials Properties of the University Erlangen-Nuremberg. Cast Astra alloys are like other nickel-base superalloys morphologically very inhomogeneous and affected by segregation. In the interdendritic region different structures with huge γ' precipitates are formed. These inhomogeneities and remaining eutectics degrade the mechanical properties, witch makes an understanding of the subsiding processes at solidification of residual melt important for the casting process and the heat treatment. This is why the last stage solidification in the interdendritic region was analyzed. With the help of focused ion beam nanotomography, three different structures identified from 2-D sections could be assigned to one original 3-D structure. It was pointed out, that only the orientation of the plane of the 2-D cut influences the appearance in the 2-D section. The tomography information was used to explain the development during solidification and to create a model of last stage solidification. The interdendritic region is solidifying under the development of eutectic islands. The structure nucleates eutectically epitaxially at primary dendrite arms, with formation of fine γ/γ' precipitates. During solidification the γ' precipitates coarsen in a rod-like structure, and end up in large γ' precipitates. Simulations and other investigations could approve this model. First three

  3. Ni-based superalloys for turbine discs

    Science.gov (United States)

    Furrer, David; Fecht, Hans

    1999-01-01

    Superalloys have been developed for specific, specialized properties and applications. One of the main applications for nickel-based superalloys is gas-turbine-engine disc components for land-based power generation and aircraft propulsion. Turbine engines create harsh environments for materials due to the high operating temperatures and stress levels. Hence, as described in this article, many alloys used in the high-temperature turbine sections of these engines are very complex and highly optimized.

  4. Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

    Directory of Open Access Journals (Sweden)

    Yuan Jin

    2015-12-01

    Full Text Available Grain growth experiments were performed on Inconel™ 718 to investigate the possible correlation of the annealing twin density with grain size and with annealing temperature. Those experiments were conducted at different temperatures in the δ supersolvus domain and under such conditions that only capillarity forces were involved in the grain boundary migration process. In the investigated range, there is a strong inverse correlation of the twin density with the average grain size. On the other hand, the twin density at a given average grain size is not sensitive to annealing temperature. Consistent with previous results for pure nickel, the twin density evolution in Inconel™ 718 is likely to be mainly controlled by the propagation of the pre-existing twins of the growing grains; i.e., the largest ones of the initial microstructure. Almost no new twin boundaries are created during the grain growth process itself. Therefore, the twin density at a given average grain size is mainly dependent on the twin density in the largest grains of the initial microstructure and independent of the temperature at which grains grow. Based on the observations, a mean field model is proposed to predict annealing twin density as a function of grain size during grain growth.

  5. SUPERALLOYS: AN INTRODUCTION WITH THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    S. S. Raza

    2015-09-01

    Full Text Available Nickel based superalloys are commonly used materials in the aero industry and more specifically in the hot section of aero engines. These nickel and nickel iron based superalloys are precipitation strengthened alloys with a face centered cubic gamma matrix. Alloy 718, Allvac 718Plus and Waspaloy have been of great interest in the present study. Alloy 718 is a precipitation strengthened nickel-iron based alloy having gamma double prime phase (Ni3Nb as a main strengthening phase up to 650 °C. Waspaloy, another precipitation strengthened nickel base superalloy, has a very good strength at temperatures up to ~750 °C whereas Allvac 718Plus is a newly developed nickel based precipitation strengthened superalloy which retains good mechanical properties at up to ~700 °C. These three alloys were investigated in terms of how their respective solidification process reveals upon cooling.Latent heat of soloidification has been estimated for all three alloys. Differential thermal analyses (DTA have been used to approach the task. It was seen that Waspaloy has the smallest solidification range whereas Allvac 718Plus has the largest solidification interval in comparison. 

  6. The influence of the laser scan strategy on grain structure and cracking behaviour in SLM powder-bed fabricated nickel superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Carter, Luke N. [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Martin, Christopher; Withers, Philip J. [Manchester Materials Science Centre, University of Manchester, Manchester M13 9PL (United Kingdom); Attallah, Moataz M., E-mail: M.M.Attallah@Bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2014-12-05

    Highlights: • Laser scanning strategies in Selectively Laser Melted (SLM) of CM247LC were studied. • A bi-modal grain structure has been identified due to the island scan strategy. • EBSD and MicroCT were used to show the influence of the scan strategy. • The island strategy affects the crystrallographic orientation and crack formation. • A possible explanation for this structure is presented based on the microstructural evidence. - Abstract: During the development of a processing route for the Selective Laser Melting (SLM) powder-bed fabrication of the nickel superalloy CM247LC it has been observed that the ‘island’ scan-strategy used as standard by the Concept Laser M2 SLM powder-bed system strongly influences the grain structure of the material. Optical and SEM micrographs are presented to show the observed grain structure in the SLM fabricated and Hot Isostatically Pressed (HIPped) material. The repeating pattern shown in the grain structure has been linked to the overlapping of the ‘island’ pattern used as standard in the Concept Laser M2 powder-bed facility. It is suggested that the formation of this bi-modal grain structure can be linked to the heat transfer away from the solidifying melt pool. The concept of a ‘band’ heating effect across each ‘island’ rather than ‘moving point’ heating has been suggested and has been supported by Electron Back Scattered Diffraction (EBSD) evidence. For comparison an EBSD map from a sample formed using a simple ‘back-and-forth’ strategy has also been presented and reveals a dramatically different grain structure and crystallographic orientation. MicroCT evidence, supported by SEM microscopy, shows that in the as-fabricated material the bimodal structure caused by the ‘island’ scan-strategy translates directly into the macroscopic pattern for the regions of extensive weld cracking associated with the SLM fabrication of γ′ hardenable materials. Similar microCT data has shown that

  7. Comments on the paper: 'Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal'

    Science.gov (United States)

    Srinivasan, Bikshandarkoil R.; Naik, Suvidha G.; Dhavskar, Kiran T.

    2016-02-01

    We argue that the 'L-aspartic acid nickel chloride' crystal reported by the authors of the title paper (Optics Communications, 291 (2013) 304-308) is actually the well-known diaqua(L-aspartato)nickel(II) hydrate crystal.

  8. Benefits of high gradient solidification for creep and low cycle fatigue of AM1 single crystal superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Steuer, S., E-mail: Susanne.Steuer@ensma.fr [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Villechaise, P. [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France); Pollock, T.M. [Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106-5050 (United States); Cormier, J. [Institut Pprime, CNRS – ENSMA – Université de Poitiers, UPR CNRS 3346, Department of Physics and Mechanics of Materials, ENSMA – Téléport 2, 1 avenue Clément Ader, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France)

    2015-10-01

    The influence of high thermal gradient processing on the creep and low cycle fatigue properties of the AM1 Ni-based single crystal superalloy has been studied. Isothermal creep (from 750 °C up to 1200 °C) and low cycle fatigue (750 °C and 950 °C) experiments were performed for AM1 alloy solidified with a conventional radiation cooled (Bridgman) and higher thermal gradient liquid-metal cooled (LMC) casting process to produce coarse and finer-scaled dendritic structures, respectively. There was no significant effect of the casting technique on creep properties, due to the very similar microstructures (γ′-size and γ-channel width) established after full heat treatment of both Bridgman and LMC samples. For low cycle fatigue properties, the benefit of the higher gradient LMC process was dependent on the testing temperature. At 750 °C, cracks primarily initiated at pores created by solidification shrinkage in both Bridgman and LMC samples. Samples produced by the LMC technique demonstrated fatigue lives up to 4 times longer, compared to the Bridgman samples, due to refined porosity. At 950 °C the low cycle fatigue properties of the LMC and conventionally solidified material were not distinguishable due to a shift of crack initiation sites from internal pores to oxidized surface layers or near-surface pores. The benefit of the LMC approach was, however, apparent in fatigue at 950 °C when testing in a vacuum environment. Based on these results, a crack initiation model based on the local slip activity close to casting defect is proposed.

  9. Synthesis, characterization and crystal structure of new nickel molybdenum complex with the pyridine dicarboxylic acid ligand: Novel precursors for nickel molybdate nanoparticles

    Indian Academy of Sciences (India)

    HAMID EMADI; BAHAREH TAMADDONI JAHROMI; ALI NEMATI KHARAT

    2017-03-01

    A novel nickel molybdenum complex with the 2,6-pyridine dicarboxylic acid ligand was successfully synthesized and characterized by thermogravimetric analysis and single crystal X-ray crystallography. The single-crystal X-ray data revealed that the structure is a hydrated 1-D polymer with two different Ni sites.The synthesized complex was then used as a new precursor for the preparation of the related nickel molybdate nanoparticles. The crystallinity and morphology of the nickel molybdate nanoparticles were characterized by powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmittance electron microscopy (TEM), and Photoluminescence (PL) spectroscopy.

  10. Effects of Hf and B on high temperature low stress creep behavior of a second generation Ni-based single crystal superalloy DD11

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y.S. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhang, J.; Luo, Y.S. [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Li, J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); NCS Testing Technology Co., Ltd., Beijing 100081 (China); Tang, D.Z., E-mail: Dingzhongtang621@163.com [Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing 100095 (China)

    2016-08-30

    The as-cast and heat-treated microstructures and high temperature creep properties have been investigated in four experimental Ni-based single crystal superalloys containing various levels of Hf addition (0–0.4 wt%) and B addition (0–0.02 wt%). The experimental results indicated that the creep rupture life showed an improvement with individual addition of Hf, but it was decreased with individual addition of B. The elemental partitioning ratio and interfacial dislocation spacing of γ/γ′ were obviously changed with individual Hf or B additions. Meanwhile, the formation of secondary phases, such as the blocky MC carbide, script-like shape M{sub 3}B{sub 2} phases, was observed in the creep samples, which was also closely related to the high temperature creep behaviors. The high volume fraction of residual (γ+γ′) eutectics was mainly attributed to the significant decrease of creep rupture life for the present experimental alloy containing both Hf and B additions. This study is helpful to better understand Hf and B's role of strengthening mechanism and to optimize Hf and B additions in single crystal superalloys.

  11. Approximate evaluation of the density of single-crystal heat-resistant nickel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Petrushin, N.V.; Ignatova, I.A.; D`yachkova, L.A.

    1992-03-01

    On the basis of the generalization and analysis of the author`s and of published experimental data an analytical dependence is obtained of the density of single-crystal heat-resistant nickel alloys on their chemical composition which was characterized by the mean atomic mass of the alloy. 9 refs., 2 tabs.

  12. Reproducible low contact resistance in rubrene single-crystal field-effect transistors with nickel electrodes

    NARCIS (Netherlands)

    Hulea, I.N.; Russo, S.; Molinari, A.; Morpurgo, A.F.

    2006-01-01

    We have investigated the contact resistance of rubrene single-crystal field-effect transistors (FETs) with nickel electrodes by performing scaling experiments on devices with channel length ranging from 200 nm up to 300 μm. We find that the contact resistance can be as low as 100 Ω cm with narrowly

  13. The correlation between the temperature dependence of the CRSS and the formation of superlattice-intrinsic stacking faults in the nickel-base superalloy PWA 1480. [critical resolved shear stress

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1989-01-01

    The PWA 1480 nickel-base superalloy is known to exhibit a unique minimum in the critical resolved shear stress (CRSS) at about 400 C. This paper reports an observation of a deformation mechanism whose temperature dependence correlates exactly with the reduction in the CRSS. It was found that, after monotonic or cyclic deformation of PWA 1480 at 20 C, the deformation substructures typically contain high density of superlattice-intrinsic stacking faults (S-ISFs) within the gamma-prime precipitates. As the temperature of deformation is increased, the density of S-ISFs is reduced, until finally no faults are observed after deformation in the range from 400 to 705 C. The reduction in the fault density corresponds exactly to the reduction in the CRSS, and the temperature at which the fault density is zero corresponds with the minimum in the CRRS. Two possible mechanisms related to the presence of the S-ISFs in the alloy are considered.

  14. Investigation of the Mechanical Properties and Microstructure of Nickel Superalloys Processed in Shear Forming / Identyfikacja Właściwości Mechanicznych Oraz Mikrostruktury Superstopów Niklu Przetwarzanych W Procesie Kształtowania Obrotowego

    Directory of Open Access Journals (Sweden)

    Żaba K.

    2015-12-01

    Full Text Available The paper presents the research results of the mechanical properties and microstructure of the material in initial state and parts made from nickel superalloy Inconel®718 in the rotary forming process with laser heating. In the first step was carried out basic research of chemical composition, mechanical properties, hardness and microstructure of sheet in initial state. Then from the metal sheet, in industrial conditions, was made axisymmetric parts in the flow and shear forming with laser heating. Parts were subjected to detailed studies focused on the analysis of changes in the mechanical properties and microstructure in the relation to the material in initial state. The analysis was based on the tests results of strength and plastic properties, hardness, microstructural observations and X-ray microanalysis in the areas where defects appear and beyond. The results are presented in the form of tables, charts, and photographs of the microstructure.

  15. Material removal mechanism of belt grinding GH4169 nickel-based superalloy%GH4169镍基高温合金砂带磨削材料去除研究

    Institute of Scientific and Technical Information of China (English)

    苗淼

    2015-01-01

    提出了一种 GH4169镍基高温合金磨削新方法———恒压力堆积磨料砂带磨削方法。该方法运用恒压力砂带磨削技术实现磨削过程的压力控制,从而减少磨削过程中切削力的变化对磨削特性的影响,并且采用具有自锐作用的堆积磨料砂带实现 GH4169镍基高温合金材料的高效率磨削加工。通过正交实验法对镍基高温合金材料试件进行磨削实验,分析了砂带线速度、磨削压力、振动频率等磨削工艺参数的影响,根据极差分析方法得到了影响材料去除率的因素及砂带磨损的最优工艺。%A new method which was grinding at constant pressure with accumulated abrasive belt was proposed to grind nickel-base superalloy GH41 69 It used constant pressure grinding technology to achieve pressure control in the process of grinding so as to reduce the impact of cutting force on grinding characteristic and obtain high efficiency high precision grinding of hard machining material by adopting accumulative abrasive belt with self-sharpening effect By orthogonal grinding experiments on nickel-base superalloy specimens the impacts of grinding process parameters such as abrasive belt velocity grinding pressure and vibration frequency were analyzed The optimal process were obtained according to range analysis which influenced material removal and belt wear.

  16. Simulation study of directional coarsening (rafting) of gamma' in single crystal nickel-aluminum

    Science.gov (United States)

    Zhou, Ning

    Dislocation propagation in and work hardening of gamma channels and directional coarsening (rafting) of gamma' precipitates are the major microscopic processes taking place during high temperature deformation of single crystal Ni-base superalloys. Understanding of those processes is crucial for developing improved models of creep and fatigue of turbine blades in aircraft engines. Recent investigations of rafting in superalloys demonstrate clearly the importance of elastic modulus difference between the gamma and gamma' phases and dislocation-level activities in the gamma-channels in determining the kinetic pathway of the processes. The elastic modulus difference can lead to the non-uniform distribution of stresses through the interaction with the lattice misfit and external load. While work hardening in the gamma channels has a direct effect on differentiation of the stress state in the vertical and horizontal channels and on gamma/gamma' interface coherency and energy, and hence influences the diffusive flow and morphological changes of the gamma/gamma' microstructure. In turn, changes in particle shape and coherency of the interface alter the local stress state and thereby the Peach-Koehler force on dislocations. Although existing models treating these processes separately can offer a qualitative explanation about the direction of rafting for typical superalloys, a complete quantitative understanding of rafting phenomena requires these processes to be treated simultaneously in a common framework because of their intimate coupling. The objective of this thesis is to develop an integrated computational approach in simulating simultaneous evolution of both gamma/gamma' microstructure and dislocations in an elastically anisotropic and inhomogeneous system by using a single, consistent phase field methodology. In particular, the phase field dislocation model is used to simulate the initial dislocation gamma channel filling process and calculate stress distribution

  17. Rotating bending fatigue property of the Ni3Al-based single crystal superalloy IC6SX at 900°C

    Science.gov (United States)

    Jiang, Liwu; Li, Shusuo; Han, Yafang

    2017-03-01

    The high cycle fatigue behavior of a Ni3Al base single crystal superalloy IC6SX has been investigated at 900°C in this work. The specimens used for the fatigue tests were prepared by screw selection crystal method in a directional solidification furnace. The rotating bending fatigue tests were carried out at 900°Cin air, the stress ratio of R(σmax/σmin) was -1, and the rotating speed of the fatigue tests was 6500r/min(108Hz). The stress-fatigue cycle life (S-Nf) curve was obtained based on the fatigue tests, and the fracture surfaces were examined using scanning electron microscopy (SEM). It has been found that the median fatigue strength is 457.5MPa and the safety fatigue strength is 413.93MPa. And the fatigue fracture was composed of three different characteristic regions.

  18. Twin domains in nickel-oxide type crystals

    Science.gov (United States)

    Mandel, V. S.

    1997-04-01

    NiO-type antiferromagnets, 2-valent oxides of 3d transition metals: MnO, CoO and NiO, are isomorphic in the paramagnetic state. They have a face-centered cubic lattice. Below the Neel temperature TN, magnetic ordering in these crystals is accompanied by a distortion of the cubic lattice. Although this distortion is very slight, it reduces the crystal symmetry. Because the cubic crystal has several equivalent directions which can become distortion axes, below TN the crystal undergoes twinning, splitting up into several macroscopic regions known as T-domains. Crystals were grown by three methods: Verneuil, epitaxy from the gas phase, and flux-melt growth. They were investigated via polarization microscopy, X-ray topography and antiferromagnetic resonance. The use of a variety of growth methods and investigating techniques made it possible to obtain reliable information about the structure of NiO-type crystals.

  19. XPS surface analysis of chemical and ion nitred Ni-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Cappelli, E.; Nistico' , N.; Giunta, G.; Musicanti, M.; Bovaro, A.; Visconti, A. (Eniricerche, Monterotondo (Italy) Soliveri SpA, Caravaggio (Italy) Vacuum SpA, Trezzano S.N. (Italy))

    This paper reports on an investigation of the possibility of inducing surface modifications in a nickel base superalloy through different nitride treatment methods analogous to conventional hardening processes for steels. The aim was to confer, to the external surface of the superalloy, chemical and mechanical characteristics such as to make possible the nucleation and growth of a follow-up layer of a ceramic material (chemical vapour deposited TiN). The idea was to obtain good materials adhesion characterized by optimum properties - elastic modulus, thermal expansion, crystal structure, morphology, etc. The treatments led to significant increases in surface hardness and positively influenced both the nucleation process and TiN growth, as well as, substrate and coating adhesion. Results of x-ray photoelectron spectroscopy, XPS, of the surface and internal layers, together with microstructural examinations (SEM- EDX, XRD), evidenced the presence of nitrogen and the formation of nitrides (CrN and TiN) responsible for the induced modifications.

  20. Laser-Aided Direct Writing of Nickel-Based Single-Crystal Super Alloy (N5)

    Science.gov (United States)

    Wang, Yichen; Choi, Jeongyoung; Mazumder, Jyoti

    2016-12-01

    This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

  1. Nickel

    Science.gov (United States)

    The agricultural significance of nickel (Ni) is becoming increasingly apparent; yet, relative few farmers, growers, specialists or researchers know much about its function in crops, nor symptoms of deficiency or toxicity. The body of knowledge is reviewed regarding Ni’s background, uptake, transloc...

  2. Single crystal Processing and magnetic properties of gadolinium nickel

    Energy Technology Data Exchange (ETDEWEB)

    Shreve, Andrew John [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    GdNi is a rare earth intermetallic material that exhibits very interesting magnetic properties. Spontaneous magnetostriction occurs in GdNi at T{sub C}, on the order of 8000ppm strain along the c-axis and only until very recently the mechanism causing this giant magnetostriction was not understood. In order to learn more about the electronic and magnetic structure of GdNi, single crystals are required for anisotropic magnetic property measurements. Single crystal processing is quite challenging for GdNi though since the rare-earth transition-metal composition yields a very reactive intermetallic compound. Many crystal growth methods are pursued in this study including crucible free methods, precipitation growths, and specially developed Bridgman crucibles. A plasma-sprayed Gd2O3 W-backed Bridgman crucible was found to be the best means of GdNi single crystal processing. With a source of high-quality single crystals, many magnetization measurements were collected to reveal the magnetic structure of GdNi. Heat capacity and the magnetocaloric effect are also measured on a single crystal sample. The result is a thorough report on high quality single crystal processing and the magnetic properties of GdNi.

  3. Mott Electrons in an Artificial Graphenelike Crystal of Rare-Earth Nickelate S.

    Energy Technology Data Exchange (ETDEWEB)

    Middey, Srimanta; Meyers, Derek J.; Doennig, D.; Kareev, M; Liu, Xiaoran; Cao, Yanwei; Yang, Zhenzhong; Shi, Jinan; Gu, Lin; Ryan, Philip J.; Freeland, J. W.; Pentcheva, R.; Chakhalian, J.

    2016-02-05

    Deterministic control over the periodic geometrical arrangement of the constituent atoms is the backbone of the material properties, which, along with the interactions, define the electronic and magnetic ground state. Following this notion, a bilayer of a prototypical rare-earth nickelate, NdNiO3, combined with a dielectric spacer, LaAlO3, has been layered along the pseudocubic [111] direction. The resulting artificial graphenelike Mott crystal with magnetic 3d electrons has antiferromagnetic correlations. In addition, a combination of resonant X-ray linear dichroism measurements and ab initio calculations reveal the presence of an ordered orbital pattern, which is unattainable in either bulk nickelates or nickelate based heterostructures grown along the [001] direction. These findings highlight another promising venue towards designing new quantum many-body states by virtue of geometrical engineering.

  4. Effect of a Transverse Magnetic Field on Stray Grain Formation of Ni-Based Single Crystal Superalloy During Directional Solidification

    Science.gov (United States)

    Xuan, Weidong; Liu, Huan; Lan, Jian; Li, Chuanjun; Zhong, Yunbo; Li, Xi; Cao, Guanghui; Ren, Zhongming

    2016-08-01

    The effect of a transverse magnetic field on stray grain formation during directional solidification of superalloy was investigated. Experimental results indicated that the transverse magnetic field effectively suppressed the stray grain formation on the side the primary dendrite diverges from the mold wall. Moreover, the quenched experimental results indicated that the solid/liquid interface shape was obviously changed in a transverse magnetic field. The effect of a transverse magnetic field on stray grain formation was discussed.

  5. Growth, spectral, optical and thermal characterization of new metallorganic crystal--bisthiourea nickel chloride.

    Science.gov (United States)

    Ramachandraraja, C; Joseph, A Antony; Sundararajan, R S; Shankar, V Siva; Murugakoothan, P

    2009-12-01

    The novel nonlinear optical single crystal of bisthiourea nickel chloride (BTNC) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectra were recorded to determine the symmetries of molecular vibrations. Presence of various functional groups of BTNC was identified through FTIR and Raman spectroscopic analyses. Optical absorbance spectrum recorded in the wavelength range of UV-vis-NIR revealed that this crystal has good optical transparency in the range 200-2000 nm. The second harmonic generation test of BTNC revealed the nonlinear nature of the crystal. The BTNC crystal was analyzed by differential thermal and thermo gravimetric analysis (DTA-TGA) to obtain its thermal stability.

  6. Atom probe tomography of secondary γ′ precipitation in a single crystal Ni-based superalloy after isothermal aging at 1100 °C

    Energy Technology Data Exchange (ETDEWEB)

    Tan, X.P., E-mail: xptan1985@gmail.com [IM 2NP, UMR 7334 CNRS, Université Aix-Marseille, 13397 Marseille Cedex 20 (France); Mangelinck, D.; Perrin-Pellegrino, C. [IM 2NP, UMR 7334 CNRS, Université Aix-Marseille, 13397 Marseille Cedex 20 (France); Rougier, L. [LSMX, MXG, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Gandin, Ch.-A. [CEMEF, UMR 7635 CNRS, MINES ParisTech, 06904 Sophia Antipolis (France); Jacot, A. [LSMX, MXG, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Ponsen, D.; Jaquet, V. [Snecma-SAFRAN Group, Service YQGC, 92702 Colombes (France)

    2014-10-25

    Highlights: • Bimodal size distribution of γ′ precipitates occurs after isothermal aging at 1100 °C. • Characterization of secondary γ′ by atom probe tomography. • It is proposed that the secondary γ′ occurs via a non-classical nucleation. • The coarsening of secondary γ′ precipitates well obeys the classical LSW theory. - Abstract: Secondary γ′ precipitation in a commercial single crystal Ni-based superalloy after the 1100 °C isothermal aging has been investigated by atom probe tomography. After the isothermal aging for 300 s, 1800 s and 3600 s, a bimodal size distribution of larger primary γ′ precipitates and numerous smaller secondary γ′ precipitates was obtained. It is proposed that the secondary γ′ precipitated via a non-classical nucleation mode. The coarsening of secondary γ′ precipitates well obeys the classical LSW theory.

  7. Diffusion aluminide coatings for internal surface of rhenium- and rhenium-ruthenium-containing single-crystal superalloys turbine blades: Part I

    Science.gov (United States)

    Mubovadzhyan, S. A.; Galoyan, A. G.

    2012-09-01

    Process of formation rhenium or refractory carbides based diffusion barrier layer (coating) on internal surface of rhenium- and rhenium-ruthenium-containing single-crystal high-temperature alloys (superalloy) turbine blades, prior to diffusion aluminide coating deposition, is studied. It is shown that diffusion barrier layer is preventing deleterious secondary reaction zone formation under aluminide coating during long-term high-temperature operation. The kinetics of powder carburizing process of rhenium- and rhenium-ruthenium-containing high-temperature alloys is investigated, and conditions for carburizing these alloys are determined. The phase composition of the surface layer after carburizing is studied, and the effect of the fractional composition of a carbon-based powder mixture on the carburizing rate is determined.

  8. Fatigue, creep, long term ageing of nickel based superalloys for turbine disks and blades of the ATSF; Fatigue, fluage, vieillissement a long terme des superalliages a base de nickel pour disques et aubes de turbine de l'ATSF

    Energy Technology Data Exchange (ETDEWEB)

    Mendez, J.; Villechaise, P.; Jouiad, M.; Flageolet, B. [CEMES - Centre d' Elaboration de Materiaux et d' Etudes Structurales, 31 - Toulouse (France); Clement, N.; Coujou, A.; Pettinari-Sturmel, F.; Raujol, S. [Ecole Nationale Superieure de Mecanique et d' Aerotechnique (ENSMA), LMPM UMR 6617, 86 - Poitiers (France); Locq, D.; Caron, P. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), 92 - Chatillon (France)

    2002-07-01

    This paper deals with the coordinated research program on the development of high temperature alloys, as the NR3, to solve ageing problems of the superalloys used in the supersonic plane. The document deals specifically with the fatigue, creep, long term ageing of the NR3 for blades. (A.L.B.)

  9. Crystal Structure of a Nickel(Ⅱ) Complex with Asymmetric L-Histidine Ligand

    Institute of Scientific and Technical Information of China (English)

    JIN Yi; CHE Yun-Xia; ZHENG Ji-Min

    2006-01-01

    A novel nickel(Ⅱ) complex with L-histidine has been synthesized and solved by single-crystal X-ray diffraction analysis at physiological pH. The title complex (C7H16NiN4O6S, Mr= 343.01) crystallizes in monoclinic, space group P21 with a = 7.2194(7), b = 7.5968(7), c =12.2797(11) (A), β = 93.3110(10)°, V = 672.35(11) (A)3, Z = 2, Dc= 1.694 g/cm3, F(000) = 356,μ(MoKα) = 1.626 mm-1, T = 293(2) K, the final R = 0.0184 and wR = 0.0426 for 2207 observed reflections with I > 2σ(Ⅰ). The complex provides insights into a possible structural arrangement between nickel (Ⅱ) and L-histidine which may be physiologically important and abundantly present in biological systems.

  10. Crystal Structure of [Bis(L-AlaninatoDiaqua]Nickel(II Dihydrate

    Directory of Open Access Journals (Sweden)

    Awni Khatib

    2009-01-01

    Full Text Available The title complex, [Ni(C3H6O2N2(H2O2]⋅2H2O, has been prepared from nickel(II chloride in aqueous solution by adding L-alanine and potassium hydroxide. It has been crystallized from aqueous solution, and its structure was determined by X-ray structure analysis. The nickel(II ion adopts distorted octahedral coordination geometry with two bidentate L-alanine molecules and two water molecules. The complex is neutral and dihydrated. The crystal structure shows the hydrogen bonding between water and amide hydrogens within the lattice, and each fragment of the complex contains two water molecules as hydrated water. The L-alaninato ligand skeleton of the compound adopts the most stable trans-III configuration in the solid state. The alternating two five-membered chelate rings are in the stable gauche conformation.

  11. Synthesis, Crystal Structure, and Antimicrobial Properties of [Diaquabis(hexamethylenetetraminediisothiocyanato-κN]nickel(II  Complex

    Directory of Open Access Journals (Sweden)

    Che Dieudonne Tabong

    2016-01-01

    Full Text Available A nickel(II complex with hexamethylenetetramine and thiocyanate ion as coligands has been synthesized and characterised by infrared spectroscopy and ultraviolet-visible spectroscopic techniques. The crystal structure of the complex was determined by single crystal X-ray diffraction and the ligands were found to coordinate terminally through N-atoms. The ligand and the complex were screened for their activity against resistant strains of bacteria (Salmonella enteric, Shigella flexneri, Escherichia coli, and Staphylococcus aureus and fungi (Candida albicans, Candida krusei, Candida parapsilosis, and Candida neoformans.

  12. Design criteria for rhenium-reduced nickel-based single-crystal alloys. Identification and computer-assisted conversion; Designkriterien fuer rheniumreduzierte Nickelbasis-Einkristalllegierungen. Identifikation und rechnergestuetzte Umsetzung

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Thomas

    2016-06-17

    In the present work, design criteria and property models for the creep strength optimization of rhenium-free nickel based single crystal Superalloys are investigated. The study focuses on a typical load condition of 1050 C and 150 MPa, which is representative for flight engine applications. Thereby the key aspect is to link chemical composition, manufacturing processes, microstructure formation and mechanistic understanding of dislocation creep through a computational materials engineering approach. Beside the positive effect of rhenium on solid solution hardening, a second mechanism in which rhenium increases high temperature creep strength is identified. It indirectly stabilizes precipitation hardening by reducing the coarsening kinetics of γ'-rafting. Five 1st and 2nd generation technical Superalloys show a comparable microstructure evolution for up to 2 % plastic elongation, while creep times differ by a factor of five. The application of a microstructure sensitive creep model shows that these coarsening processes can activate γ-cutting and thus lead to an increasing creep rate. Based on these calculations a threshold value of φ{sub γ/γ'} > 2,5 at 150 MPa is estimated. This ratio of matrix channel to raft thickness has been proofed for multiple positions by microstructure analysis of interrupted creep tests. The mechanism described previously can be decelerated by the enrichment of the γ-matrix with slow diffusing elements. The same principle also increases the solid solution strength of the γ-matrix. Therefore, the present work delivers an additional mechanistic explanation why creep properties of single phase nickel based alloys can be transferred to two phase technical Superalloys with rafted γ'-structure. Following, the best way to substitute both rhenium fundamental properties, namely a slow diffusion coefficient and a small solubility in g', has been investigated by means of CALPHAD-modeling. Only molybdenum and especially

  13. 3D discrete dislocation dynamics study of creep behavior in Ni-base single crystal superalloys by a combined dislocation climb and vacancy diffusion model

    Science.gov (United States)

    Gao, Siwen; Fivel, Marc; Ma, Anxin; Hartmaier, Alexander

    2017-05-01

    A three-dimensional (3D) discrete dislocation dynamics (DDD) creep model is developed to investigate creep behavior under uniaxial tensile stress along the crystallographic [001] direction in Ni-base single crystal superalloys, which takes explicitly account of dislocation glide, climb and vacancy diffusion, but neglects phase transformation like rafting of γ‧ precipitates. The vacancy diffusion model takes internal stresses by dislocations and mismatch strains into account and it is coupled to the dislocation dynamics model in a numerically efficient way. This model is helpful for understanding the fundamental creep mechanisms in superalloys and clarifying the effects of dislocation glide and climb on creep deformation. In cases where the precipitate cutting rarely occurs, e.g. due to the high anti-phase boundary energy and the lack of superdislocations, the dislocation glide in the γ matrix and the dislocation climb along the γ/γ‧ interface dominate plastic deformation. The simulation results show that a high temperature or a high stress both promote dislocation motion and multiplication, so as to cause a large creep strain. Dislocation climb accelerated by high temperature only produces a small plastic strain, but relaxes the hardening caused by the filling γ channels and lets dislocations further glide and multiply. The strongest variation of vacancy concentration occurs in the horizontal channels, where more mixed dislocations exit and tend to climb. The increasing internal stresses due to the increasing dislocation density are easily overcome by dislocations under a high external stress that leads to a long-term dislocation glide accompanied by multiplication.

  14. The Study of Surfaces' Micro- and Nanostructure on Interlayer Cleavages of InSe Layered Crystals Intercalated by Nickel

    Directory of Open Access Journals (Sweden)

    P.V. Galiy

    2016-03-01

    Full Text Available This paper presents the results of experimental study concerning element-phase composition, crystallographic structure, topography and electron-energy structure of interlayer cleavage (0001 surfaces, obtained for nickel intercalated (Ni3dInSe intercalate InSe layered crystals, by means of qualitative and quantitative X-ray photoelectron spectroscopy (XPS, low energy electron diffraction (LEED and scanning tunneling microscopy/spectroscopy (STM/STS. It was established that for all layered crystals' intercalates with different concentrations of nickel in initial synthesized InSe + x at.% Ni (x ≤ 10,0 % alloys and layered crystals further grown from them by Bridgman-Stockbarger method and subjected to intercalation, the maximum concentration of nickel on the cleavage (0001 surfaces of NiхInSe intercalates and, accordingly, in the interlayer gaps of up to 7.67 at. % is observed at 0.75 at. % of nickel in synthesized alloys. Nickel doesn't interact with selenium and indium and there are also no interaction with oxygen and carbon. It is established that nickel is placed in the interlayer gaps of NiхInSe intercalates and, accordingly, appears on the interlayer cleavage (0001 surfaces as fine-phase metal nickel clusters. The studied NiхInSe intercalate system is the perfect hybrid structure with the ability to use in magnetoelectronics.

  15. Fretting Fatigue Behavior of Nickel Alloy IN-100

    Science.gov (United States)

    2006-03-01

    K., B. F. Dyson, and M. McLean. “Tension-Compression Creep Asym- metry In a Turbine Disc Superalloy : Roles of Internal Stress and Thermal Age- ing...understand the fretting phenomenon and its mechanisms, but only a few have been performed on nickel-based alloys. This superalloy is considered one...excellent magnetic properties, but only at low magnetic induction. Nowadays, the need for the use of high-strength nickel-based superalloys in

  16. SHI Changxu: China's Superalloy Hero

    Institute of Scientific and Technical Information of China (English)

    XIN Ling

    2011-01-01

    Prof.Shi Changxu (Chang-hsu Shih), laureate of the State Top Scientific and Technological Award for 2010, is regarded as a pioneer in the development of superalloys in China and a world-class master of materials science with excellent leadership and strategic insights.In the 1960s, he and his colleagues worked out the first generation air-cooled nickel-based superalloy turbine blades for domestic fighter aircrafts which greatly enhanced the aeroengines' performance.Via the effective control of trace elements, he developed the low segregation technology to reduce the segregation of superalloys, for which the International Union of Materials Research Societies honored him with the "Innovations in Real Materials Award" in 1998.He advocated and promoted the research and development of carbon fibers and magnesium alloys in China as well as the establishment of the Chinese Academy of Engineering.Today, 30 years after retirement, Prof.Shi still works every day in his office to read latest research results, write advisory proposals and meet young visitors to give them his best support.

  17. Additive Manufacturing of IN100 Superalloy Through Scanning Laser Epitaxy for Turbine Engine Hot-Section Component Repair: Process Development, Modeling, Microstructural Characterization, and Process Control

    Science.gov (United States)

    Acharya, Ranadip; Das, Suman

    2015-09-01

    This article describes additive manufacturing (AM) of IN100, a high gamma-prime nickel-based superalloy, through scanning laser epitaxy (SLE), aimed at the creation of thick deposits onto like-chemistry substrates for enabling repair of turbine engine hot-section components. SLE is a metal powder bed-based laser AM technology developed for nickel-base superalloys with equiaxed, directionally solidified, and single-crystal microstructural morphologies. Here, we combine process modeling, statistical design-of-experiments (DoE), and microstructural characterization to demonstrate fully metallurgically bonded, crack-free and dense deposits exceeding 1000 μm of SLE-processed IN100 powder onto IN100 cast substrates produced in a single pass. A combined thermal-fluid flow-solidification model of the SLE process compliments DoE-based process development. A customized quantitative metallography technique analyzes digital cross-sectional micrographs and extracts various microstructural parameters, enabling process model validation and process parameter optimization. Microindentation measurements show an increase in the hardness by 10 pct in the deposit region compared to the cast substrate due to microstructural refinement. The results illustrate one of the very few successes reported for the crack-free deposition of IN100, a notoriously "non-weldable" hot-section alloy, thus establishing the potential of SLE as an AM method suitable for hot-section component repair and for future new-make components in high gamma-prime containing crack-prone nickel-based superalloys.

  18. Formation of oriented nickel aggregates in rutile single crystals by Ni implantation

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, M.M., E-mail: mmcruz@fc.ul.pt [CFMC, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Dep. Física, Fac. Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Silva, R.C. da [IST/ITN, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Pinto, J.V. [CFMC, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Borges, R.P. [CFMC, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Franco, N. [IST/ITN, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Casaca, A. [CFMC, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa—ISEL, R. Cons. Emídio Navarro 1, 1959-007 Lisboa (Portugal); Alves, E. [IST/ITN, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, E.N.10, 2686-953 Sacavém (Portugal); CFNUL, Av. Prof. Gama Pinto 2, 1649-003 Lisboa (Portugal); Godinho, M. [CFMC, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); Dep. Física, Fac. Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal)

    2013-08-15

    The magnetic and electrical properties of Ni implanted single crystalline TiO{sub 2} rutile were studied for nominal implanted fluences between 0.5×10{sup 17} cm{sup −2} and 2.0×10{sup 17} cm{sup −2} with 150 keV energy, corresponding to maximum atomic concentrations between 9 at% and 27 at% at 65 nm depth, in order to study the formation of metallic oriented aggregates. The results indicate that the as implanted crystals exhibit superparamagnetic behavior for the two higher fluences, which is attributed to the formation of nanosized nickel clusters with an average size related with the implanted concentration, while only paramagnetic behavior is observed for the lowest fluence. Annealing at 1073 K induces the aggregation of the implanted nickel and enhances the magnetization in all samples. The associated anisotropic behavior indicates preferred orientations of the nickel aggregates in the rutile lattice consistent with Rutherford backscattering spectrometry—channelling results. Electrical conductivity displays anisotropic behavior but no magnetoresistive effects were detected. - Author-Highlights: • Ni nano-aggregates were grown on TiO{sub 2} using Ni implantation with different fluences. • In the as implanted state, the aggregates size is a function of the implanted fluence. • Ni aggregates are oriented within the rutile structure-2 orientations are proposed.

  19. Crystal structures of unsymmetrically mixed β-pyrrole substituted nickel(II)-meso-tetraphenylporphyrins

    Indian Academy of Sciences (India)

    BHYRAPPA PUTTAIAH; VELKANNAN VEERAPANDIAN; SARANGI UJWAL KUMAR

    2016-07-01

    Crystal structures of solvated unsymmetrically substituted meso-tetraphenylporphyrins, 2,3,12,13, 17-pentachloro-5,7,8,10,15,18,20-hepta-phenylporphyrin, H₂TPP(Ph)₃(Cl)₅, 1 and its nickel(II), NiTPP(Ph)₃(Cl)₅, 2 were determined by single crystal XRD analysis. In addition, a new unsymmetricallysubstituted porphyrin, 2,3,12,13,17-pentacyano-5,7,8,10,15,18,20-heptaphenyl-porphinato nickel(II) complex, NiTPP(Ph)₃(CN)₅, 3 complex was synthesized and its solvated structure was examined by crystallography. These porphyrins exhibited dramatic nonplanar conformation of the macrocycle as evidenced from the averagedisplacement of the β-pyrrole carbon (±ΔCβ ) from the mean plane of the porphyrin ring and the trend in nonplanarity varies in the order: 2 (1.189(5) Å) > 1 (1.036(6) Å) > 3 (0.895(6) Å). The normal-coordinate structural decomposition analysis of these structures revealed mainly saddle distortion of the macrocycle combined with small degree of ruffled or domed distortions. The Hirshfeld surface analysis of structures 1-3 revealed solvate dependent intermolecular contacts with varying degree of H. . .H (43–49%), C. . .H (17–19%), H. . .Cl (25–30%) and N. . .H (~19%) contact contributions.

  20. Optical and Electrochemical Properties of Layered Crystals GaSe Intercalated by the Nickel

    Directory of Open Access Journals (Sweden)

    S.G. Barbutsa

    2013-10-01

    Full Text Available The presented results of the investigations of the optical and electrochemical properties indicate the possibility of intercalation of layered GaSe crystals with nickel ions. Established that the electrochemical introduction of Ni leads to a monotonic growth in electrode potential of layered semiconductors GaSe when a concentration of intercalants nNi  1018-1020сm – 3. In consequence of intercalation of nickel in GaSe crystal at T  293 K, occurred ncreases in the energy position of the exciton peak Eeks 6 meV (from 2.008 to 2.014 eV and the half-width of the exciton absorption bands of H by 5.2 meV. At a temperature T  77 K was detected non- monotonous concentration dependence of the excitonic maximum energy location for Еeks NiGaSe compounds. The dependence Еeks(nNi for these compounds are explained as a result of the introduction of competition between contributions of inter - and intralayer deformations which have the opposite signs of deformation potential.

  1. Crystal Structure of Tris(2,2'-bipyridine)nickel (Ⅱ) Tetrachlorozincate

    Institute of Scientific and Technical Information of China (English)

    林善火; 王志奎; 张百合; 胡怀明; 黄锦顺

    2000-01-01

    A bimetallic complex Ni[C10H8N2]3[ZnCl4] has been synthesized and its crystal structure determined at room temperature. The complex crystallizes in the trigonal system, space group R3c, with a = 13.343(2), b = 13.343(2), c =58. 932(12) A, V= 9087(3) A 3, Z = 12, NiZnC30N6CI14H24, Mr=734.30, Dc=1.611 g/cm3, μ= 1. 799 mm-1, F(000)=4464. Least-squares refinement of the structure leads to the agreement factors R1=0. 0278 and wR2=0. 0741 for the observable reflections. The complex consists of discrete tris (2, 2'-bipyridine) nickel (Ⅱ)cation, [Ni-(bipy)3]2+, and tetrachlorozincate anion, [ZnCl4]2-. Each nickel (Ⅱ)atom is six coordinated in an octahedron with six nitrogen atoms of three 2,2'-bipyridine ligands. The mean Ni(Ⅱ)-N bond length is 2. 089(2) A. The zinc(Ⅱ) atom is coordinated with four chloride atoms in tetrahedral geometry. The mean Zn (Ⅱ)- Cl bond length is 2. 264(1) A.

  2. Effect of dendrite arm spacing and the γ’ phase size on stress rupture properties of Ni3Al-base single crystal superalloy IC6SX

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The effect of dendrite arm spacing and the size of γ’ phase on stress rupture properties of as-cast Ni3Al-based single crystal superalloy IC6SX was studied.It has been found that the stress rupture properties were affected by dendrite arm spacing and the size of γ’ phase significantly,i.e.,the stress rupture lives of as-cast specimens under the test condition of 1100°C/120 MPa were significantly increased from about 10 h to 31 h with decreasing dendrite arm spacing and the size of γ’ phase from 3.0 μm and 1.6 μm to 1.3 μm and 0.8 μm,respectively.The creep cracks generated easily in the brittle Y-NiMo phase.Then the cracks gradually mergered and grew up during creep,and finally led to specimens fracture.The orientated coarsening of γ’ phase has been found in the stress ruptured specimens,due to the elements diffusion.However,the γ’ phase did not form the integrated structure during the short periods of 10-31 h as the creep tests lasted.

  3. Oxidation behavior and mechanism of a Ni-based single crystal superalloy with single α-Al2O3 film at 1000 °C

    Science.gov (United States)

    Pei, Haiqing; Wen, Zhixun; Zhang, Yamin; Yue, Zhufeng

    2017-07-01

    Detailed long-term of 2000 h oxidation behavior of a Ni-based single crystal superalloy was investigated at 1000 °C. In the first oxidation stage, α-Al2O3 formed immediately, and then the mass gain curve obeys the parabolic law, which corresponds to the growth of α-Al2O3 film. A single α-Al2O3 film kept on the surface of the specimen before 750 h oxidation. The oxidation is controlled by the inward diffusion of oxygen anions to react with Al cations at the oxide/metal interface. The shape of the exfoliation region of single α-Al2O3 film is closed to an annulus, in which the (Ni, Co)O layer formed due to depletion of Al. The three-layer oxide scale formed rapidly after 750 h oxidation. With the continue consumption of Al, a discontinuous inner α-Al2O3 layer formed, making oxide scale spall seriously and gain mass rapidly. The states of α-Al2O3 film, the controlled film, are different in dendrite core and interdendritic region.

  4. Oxidation behavior of a single-crystal Ni-base superalloy between 900 and 1000 {sup o}C in air

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T., E-mail: liuchunting76@yahoo.com.c [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Ma, J. [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China); Sun, X.F. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2010-02-18

    The oxidation behavior of a single-crystal Ni-base superalloy DD32 was studied in air at 900 and 1000 {sup o}C and analyzed by X-ray diffraction (XRD), scanning electron microscopy, combined with energy-dispersive X-ray spectroscopy (SEM/EDS). At 900 and 1000 {sup o}C, two oxidation steps appear in the oxidation kinetics. The first one is controlled by NiO growth and the second by Al{sub 2}O{sub 3} growth until a continuous Al{sub 2}O{sub 3} layer formed under the previously grown NiO layer after a critical time. The variations in the chemical composition due to segregations, which resulted from the solidification process, led to the formation of different kinds of oxide scale on the dendritic and interdendritic area during oxidation between 900 and 1000 {sup o}C. The scales formed between 900 and 1000 {sup o}C were complicated, and consisted of three layers: an outer columnar NiO layer with a small amount of CoO, an intermediate layer mainly composed of W{sub 20}O{sub 58}, CrTaO{sub 4}, a small amount of spinels NiCr{sub 2}O{sub 4}, NiAl{sub 2}O{sub 4} and CoAl{sub 2}O{sub 4}, an inner continuous layer of {alpha}-Al{sub 2}O{sub 3}.

  5. Effects of Jet Pressure on the Ground Surface Quality and CBN Wheel Wear in Grinding AISI 690 Nickel-Based Superalloy

    Science.gov (United States)

    Guitouni, Ahmed; Chaieb, Iheb; Rhouma, Amir Ben; Fredj, Nabil Ben

    2016-09-01

    Fluid application in grinding is getting attention as higher stock removal rates, higher surface integrity and longer wheel life are required. It is necessary to define proper conditions of application for meeting high productivity goals by lowering the specific grinding energy and reducing the temperature of the contact zone. The present study investigated the capacity of the jet pressure of a spot nozzle to improve the wear of a CBN wheel when grinding the AISI 690 superalloy. Grinding experiments were conducted with an emulsion-type cooling fluid delivered at pressure ranging from 0.1 to 4 MPa. Results show that the maximum stock removal, reached at 4 MPa, is 5 times the stock removal obtained at 0.1 MPa, while the grinding ratio at 4 MPa is 8 times that at 0.1 MPa, and there is a critical pressure (P c) around 1.5 MPa corresponding to the minimum specific grinding energy. Scanning electron microscopy of the grain tips showed that the wear mechanism shifts from breaking and dislodgment at low jet pressure to micro-fracture resulting in continuous self-sharpening of the abrasive grains. By lubricating at jet pressure close to P c, there is less thermal damage due to plowing and sliding and the resulting lower loading of the abrasive grains favors the micro-fracture of grains and thus a longer wheel life.

  6. Effects of Jet Pressure on the Ground Surface Quality and CBN Wheel Wear in Grinding AISI 690 Nickel-Based Superalloy

    Science.gov (United States)

    Guitouni, Ahmed; Chaieb, Iheb; Rhouma, Amir Ben; Fredj, Nabil Ben

    2016-11-01

    Fluid application in grinding is getting attention as higher stock removal rates, higher surface integrity and longer wheel life are required. It is necessary to define proper conditions of application for meeting high productivity goals by lowering the specific grinding energy and reducing the temperature of the contact zone. The present study investigated the capacity of the jet pressure of a spot nozzle to improve the wear of a CBN wheel when grinding the AISI 690 superalloy. Grinding experiments were conducted with an emulsion-type cooling fluid delivered at pressure ranging from 0.1 to 4 MPa. Results show that the maximum stock removal, reached at 4 MPa, is 5 times the stock removal obtained at 0.1 MPa, while the grinding ratio at 4 MPa is 8 times that at 0.1 MPa, and there is a critical pressure ( P c) around 1.5 MPa corresponding to the minimum specific grinding energy. Scanning electron microscopy of the grain tips showed that the wear mechanism shifts from breaking and dislodgment at low jet pressure to micro-fracture resulting in continuous self-sharpening of the abrasive grains. By lubricating at jet pressure close to P c, there is less thermal damage due to plowing and sliding and the resulting lower loading of the abrasive grains favors the micro-fracture of grains and thus a longer wheel life.

  7. The Effect of Microstructure on Fretting Fatigue Behavior of Nickel Alloy IN-100

    Science.gov (United States)

    2007-03-01

    2317, 2004 115 27. Sondhi, S.K. et al. Tension-compression creep asymmetry in a turbine disc superalloy : Roles if internal stress and thermal...82 5.6 Effect of Grain Size on Fatigue in Nickel-based Superalloys 83...done on correlating changes in microstructure to changes in strength for superalloys . Huther and Reppich [18] suggest the following formula for

  8. Corrosion behavior of Haynes {sup registered} 230 {sup registered} nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung [Institute for Advanced Engineering (IAE), Gyeonggi-do (Korea, Republic of). Plant Engineering Center; Kim, Min Jung [Sungkyunkwan Univ, Gyeonggi-do (Korea, Republic of). Advanced Materials Technology Research Center

    2015-07-01

    The corrosion behavior of commercially available Haynes {sup registered} 230 {sup registered} nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes {sup registered} 230 {sup registered} nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes {sup registered} 556 {sup registered}.

  9. Synthesis and crystal structures of three isophthalato-bridged macrocyclic nickel(II) complexes

    Indian Academy of Sciences (India)

    Guang-Chuan Ou; Zhi-Zhang Li; Lin Yuan; Xian-You Yuan

    2015-01-01

    Three dinuclear isophthalato-bridged nickel(II) complexes formulated as [Ni(rac-L)]2(-IPA)(ClO4)2 (1), [Ni(-L)]2(-IPA)(ClO4)2 (2) and [Ni(SS-L)]2(-IPA)(ClO4)2 (3) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyc-lotetradecane, IPA = isophthalic acid) have been isolated and characterized. Single crystal X-ray diffraction analyses revealed that the Ni(II) atoms have six-coordinated distorted octahedral environments, and the isophthalato ligand bridges two Ni(II) centres in a bis bidentate fashion to form dimers in all three complexes. The monomers of {[Ni(-L)]2(-IPA)}2+ are connected through intermolecular hydrogen bonds to generate one-dimensional left-handed helical chains in complex 3. The homochiral natures of complexes 2 and 3 have been confirmed by CD spectroscopy.

  10. Laser repairing surface crack of Ni-based superalloy components

    Institute of Scientific and Technical Information of China (English)

    王忠柯; 叶和清; 许德胜; 黄索逸

    2001-01-01

    Surface crack of components of the cast nickel-base superalloy was repaired with twin laser beams under proper technological conditions. One laser beam was used to melt the substrate material of crack, and the other to fill in powder material to the crack region. The experimental results show that the surface crack with the width of 0.1~0.3mm could be repaired under the laser power of 3kW and the scanning speed of 6~8mm/s. The repaired deepness of crack region is below 6.5mm. The microstructure of repaired region is the cellular crystal, columnar crystal dendrite crystal from the transition region to the top filled layer. The phases in repaired region mainly consisted of supersaturated α-Co with plenty of Ni, some Cr and Al, Cr23C6, Co2B, Co-Ni-Mo, Ni4B3, TiSi and VSi. The hardness of filled layer in repaired region ranged from HV0.2450 to HV0.2500, and the hardness decreases gradually from the filled layer to joined zone.

  11. The effects of temperature and strain rate on the yielding behavior of the single crystal superalloy PWA 1480

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1988-01-01

    Interrupted tensile tests were conducted on (001) oriented single crystals at temperatures from 20 to 1093 C. Two strain rates were used, 0.5 and 50 percent/min. After the tests, the deformation substructures were characterized by transmission electron microscopy. Results of these tests are given.

  12. Critical Percolation Stresses of Random Frank-Read Sources in Micron-Sized Crystals of Superalloys (Preprint)

    Science.gov (United States)

    2011-11-01

    tendency for a saturation stress value, most likely because the experimental size-effect data does not include small enough sizes of micron-sized crystals...D, Gumbsch P, Kraft O, Scripta Mater 2008; 58:587. 7) Tang H, Schwarz KW, Espinosa HD, Acta Mater 2007; 55:1607. 8) Zhou C, Biner S, Lesar R

  13. Recent trends in superalloys research for critical aero-engine components

    Energy Technology Data Exchange (ETDEWEB)

    Remy, Luc [Mine ParisTech, CNRS UMR 7633, 91 - Evry (France). Centre des Materiaux; Guedou, Jean-Yves [Snecma Safran Group, Moissy-Cramayel (France). Materials and Processes Dept.

    2010-07-01

    This paper is a brief survey of common research activity on superalloys for aero-engines between Snecma and Mines ParisTech Centre des Materiaux during recent years. First in disks applications, the development of new powder metallurgy superalloys is shown. Then grain boundary engineering is investigated in a wrought superalloy. Secondly, design oriented research on single crystals blades is shown: a damage model for low cycle fatigue is used for life prediction when cracks initiated at casting pores. The methodology developed for assessing coating life is illustrated for thermal barrier coating deposited on AMI single crystal superalloy. (orig.)

  14. Mechanically worked single crystal article

    Energy Technology Data Exchange (ETDEWEB)

    Gell, M. L.; Giamei, A. F.

    1985-07-09

    A single crystal nickel base superalloy component, such as a gas turbine blade is mechanically deformed at elevated temperature to improve the yield strength of a portion which is used at temperatures below 800/sup 0/ C., compared to a portion which is used at a higher temperature. A blade has a root which is deformed by 2-14% at 700/sup 0/-1100/sup 0/ C. and an airfoil which is not deformed. The root yield strength is increased 15-50% while the airfoil creep strength is maintained.

  15. Superalloy Lattice Block Structures

    Science.gov (United States)

    Nathal, M. V.; Whittenberger, J. D.; Hebsur, M. G.; Kantzos, P. T.; Krause, D. L.

    2004-01-01

    Initial investigations of investment cast superalloy lattice block suggest that this technology will yield a low cost approach to utilize the high temperature strength and environmental resistance of superalloys in lightweight, damage tolerant structural configurations. Work to date has demonstrated that relatively large superalloy lattice block panels can be successfully investment cast from both IN-718 and Mar-M247. These castings exhibited mechanical properties consistent with the strength of the same superalloys measured from more conventional castings. The lattice block structure also accommodates significant deformation without failure, and is defect tolerant in fatigue. The potential of lattice block structures opens new opportunities for the use of superalloys in future generations of aircraft applications that demand strength and environmental resistance at elevated temperatures along with low weight.

  16. Detection of label-free cancer biomarkers using nickel nanoislands and quartz crystal microbalance.

    Science.gov (United States)

    Martínez-Rivas, Adrián; Chinestra, Patrick; Favre, Gilles; Pinaud, Sébastien; Séverac, Childérick; Faye, Jean-Charles; Vieu, Christophe

    2010-09-07

    We present a technique for the label-free detection and recognition of cancer biomarkers using metal nanoislands intended to be integrated in a novel type of nanobiosensor. His-tagged (scFv)-F7N1N2 is the antibody fragment which is directly immobilized, by coordinative bonds, onto ~5 nm nickel islands, then deposited on the surface of a quartz crystal of a quartz crystal microbalance (QCM) to validate the technique. Biomarker GTPase RhoA was investigated because it has been found to be overexpressed in various tumors and because we have recently isolated and characterized a new conformational scFv which selectively recognizes the active form of RhoA. We implemented a surface chemistry involving an antibiofouling coating of polyethylene glycol silane (PEG-silane) (<2 nm thick) and Ni nanoislands to reach a label-free detection of the active antigen conformation of RhoA, at various concentrations. The methodology proposed here proves the viability of the concept by using Ni nanoislands as an anchoring surface layer enabling the detection of a specific conformation of a protein, identified as a potential cancer biomarker. Hence, this novel methodology can be transferred to a nanobiosensor to detect, at lower time consumption and with high sensitivity, specific biomolecules.

  17. Detection of label-free cancer biomarkers using nickel nanoislands and quartz crystal microbalance

    Directory of Open Access Journals (Sweden)

    Adrián Martínez-Rivas

    2010-09-01

    Full Text Available Adrián Martínez-Rivas1,2, Patrick Chinestra3,4, Gilles Favre3,4, Sébastien Pinaud1, Childérick Séverac1,2, Jean-Charles Faye3,4, Christophe Vieu1,21LAAS-CNRS; Université de Toulouse, Toulouse, France; 2Université de Toulouse, UPS, INSA, INP, ISAE; LAAS; Toulouse, France; 3INSERM U563, Université de Toulouse, CPTP, “Signalisation Cellulaire, GTPase Rho et cancers”, Toulouse, France; 4Institut Claudius Regaud, Biology Department, Toulouse, FranceAbstract: We present a technique for the label-free detection and recognition of cancer biomarkers using metal nanoislands intended to be integrated in a novel type of nanobiosensor. His-tagged (scFv-F7N1N2 is the antibody fragment which is directly immobilized, by coordinative bonds, onto ~5 nm nickel islands, then deposited on the surface of a quartz crystal of a quartz crystal microbalance (QCM to validate the technique. Biomarker GTPase RhoA was investigated because it has been found to be overexpressed in various tumors and because we have recently isolated and characterized a new conformational scFv which selectively recognizes the active form of RhoA. We implemented a surface chemistry involving an antibiofouling coating of polyethylene glycol silane (PEG-silane (<2 nm thick and Ni nanoislands to reach a label-free detection of the active antigen conformation of RhoA, at various concentrations. The methodology proposed here proves the viability of the concept by using Ni nanoislands as an anchoring surface layer enabling the detection of a specific conformation of a protein, identified as a potential cancer biomarker. Hence, this novel methodology can be transferred to a nanobiosensor to detect, at lower time consumption and with high sensitivity, specific biomolecules.Keywords: nickel nanoislands, cancer biomarkers, quartz crystal microbalance, PEG-silane, RhoA protein, nanobiosensor

  18. ICP-OES法测定镍基合金中9种微量元素%Determination of 9 Trace Elements in Nickel-base Superalloy by ICP-OES

    Institute of Scientific and Technical Information of China (English)

    彭明斌

    2016-01-01

    建立了ICP-OES(等离子体发射光谱法)测定镍基合金中9种微量元素的测试方法。采用3:1体积比浓盐酸和浓硝酸混酸通过微波消解仪消解0.2 g样品制备样品溶液。标准溶液通过基体匹配法制备,各元素标准曲线线性相关系数大于0.999。本方法各元素的方认检测限在0.004 mg/L到0.30 mg/L之间。应用本方法进行测试,9种元素的相对标准偏差( n=7)均小于5%,加标回收率在95.0%到102.7%之间。实验结果表明本方法精密度好、准确度高,满足日常分析的要求。%A test method for determination of 9 trace elements in nickel-base superalloy by ICP-OES ( Inductively Coupled Plasma Optical Emission) was established. Sample solutions were prepared by 0. 2 g sample with 3:1 volume ratio of concentrated hydrochloric acid and concentrated nitric acid in microwave digestion instrument. Standard solutions were prepared by matrix matching method, and after resting, linear correlation coefficient of each element was greater than 0. 999. Method detection limit of each elements in this method were 0. 26 mg/L to 0. 005 mg/L. Performing tests according to this test method, the relative standard deviation of each element was less than 5%, and the recovery were 95. 0% to 102. 7%. Test results indicated that the precision and accuracy of this method were good and can meet the analysis requirement.

  19. Synthesis, characterization and magnetic property of 3D flower-like nickel sulphide nanocrystals through decomposing bis(thiourea) nickel(II) chloride crystals

    Indian Academy of Sciences (India)

    Peng-Fei Yin; Li-Li Sun; Chao Zhou; Yu-Heng Sun; Xiang-Yu Han; Cheng-Rong Deng

    2015-02-01

    Three-dimensional (3D) flower-like cubic Ni3S4 nanoplates with single crystalline nature were successfully prepared through decomposing bis(thiourea) nickel(II) chloride crystals (BTNC). The samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, selected area electron diffraction and Raman spectroscopy. Results show that the as-prepared products are pure cubic Ni3S4 and stable in range of 180–220°C with single crystal nature providing high surface areas, and higher reaction temperature leads to lower surface areas. Typical Raman peaks of the as-synthesized 3D flower-like cubic Ni3S4 at 200°C are located at 239, 286, 337, 379, 423, 478 and 630 cm-1. Magnetization measurement indicates that single crystalline Ni3S4 nanoplates prepared at 200°C displays antiferromagnetic behaviour.

  20. Synthesis and crystal structure of nickel complex of N, N-bis(benzimidazol-2-yl-methyl)amine

    Science.gov (United States)

    Xu, Jing-Yuan; Gu, Wen; Li, Ling; Yan, Shi-Ping; Cheng, Peng; Liao, Dai-Zheng; Jiang, Zong-Hui

    2003-01-01

    A new nickel(II) complex, [NiL 2]Cl 2 (L= N, N-bis(benzimidazol-2-yl-methyl)amine), was synthesized and its crystal structure was determined. According to X-ray crystallographic studies, each nickel(II) ion was six-coordinated with six nitrogen atoms of two L ligands. The complex crystallizes in triclinic system, space group P 1¯, a=9.764(3) Å, b=11.032(3) Å, c=16.402(5) Å, α=80.529(6)°, β=79.180(7)°, γ=74.232(6)°, and Z=2. The title complex forms two-dimensional hydrogen bond network structures between the chlorine atoms and the nitrogens of L. The IR and UV spectroscopy were measured. The absorption bands of d-d electron transition are assigned, the values of Dq and B were calculated according to the electronic spectrum of the complex.

  1. Solidification microstructure of directionally solidified superalloy under high temperature gradient

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effect of solidification rate on the microstructure development of nickel-based superalloy under the temperature gradient of 500 K·cm-1 was studied. The results show that, with the increase of directional solidification rate from 50 to 800 μm·s-1, both the primary and the secondary dendrite arm spacings of the alloy decrease gradually, and the dendrite morphologies transform from coarse dendrite to superfine dendrite. The sizes of all precipitates in the superalloy decrease gradually. The morphology of ...

  2. Aging of vacuum plasma sprayed MCrAlY protective layers and their interaction with nickel- and cobalt-based γ/γ'-superalloys; Alterung von Vakuum-plasmagespritzten MCrAlY-Schutzschichten und ihre Wechselwirkung mit Nickel- und Cobalt-basierten γ/γ'-Superlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Terberger, Philipp J.

    2015-07-01

    γ/γ' single crystal superalloys with plasma-sprayed thermal barrier coating systems are used as turbine rotor blades in gas turbines if the blades are exposed to high temperatures and high mechanical loads. A bond coat (BC) is part of the thermal barrier coating system. It protects the substrate from oxidation and ensures good bonding of the ceramic coating that serves as a thermal insulator. MCrAlY (M=Ni,Co) alloys are commonly used as BCs. They form a protective Al{sub 2}O{sub 3} layer. This study investigates four different vacuum plasma-sprayed MCrAlY BCs with and without Re after thermal treatment of up to 1000 h at 1044 C in air. The employed substrates are the Ni-based superalloy ERBO1 and the novel Co-based γ/γ' superalloy ERBOCo-1. Additionally, the ternary γ/γ' alloy Co-9Al-9W (in at.%) was aged with a BC for up to 500 h at 900 C. Up to now little is known about the interaction of the Co-based substrates and the BCs. Oxidation and Al depletion of the BC as well as the interdiffusion of BCs and substrates are analysed primarily on the basis of SEM/EDX and XRD. The effect of Y and Hf on the microstructure of the oxide scale is discussed. Rate constants show that Hf results in higher oxidation rates while Re slows down the oxidation. The influence of the alloying elements on the BC microstructure is described. For example, Co prevents the formation of γ' phase, Re slows down diffusion and results in the formation of brittle phases. The choice of substrate material has no measurable influence on the oxidation. Qualitative and quantitative analysis of the interdiffusion zone (IDZ) shows that the choice of substrate surface pre-treatment (grit blasting or grinding) has a major influence on the interdiffusion behaviour with the BC. Grinding results in a thinner IDZ and fewer topologically closed packed (TCP) phases. The reason for this is the recrystallisation of the single crystal substrate. A study of the influence of the substrate

  3. Anisotropic growth of single-crystal graphite plates by nickel-assisted microwave-plasma chemical-vapor deposition

    Science.gov (United States)

    Badzian, Teresa; Badzian, Andrzej; Roy, Rustum; Cheng, Shang-Cong

    2000-02-01

    Growth of single-crystal graphite free-standing plates has been achieved by a microwavehydrogen-plasma etching of graphite powder and nickel mesh. The plates resemble a knife blade and grow in the direction with long crystals exceeding 100 μm. Hexagonal growth features at the edges and electron diffraction patterns confirm the single-crystal nature of these ultrathin plates. Electron microprobe and Raman spectroscopy indicate the presence of graphite. Diamond crystals nucleate on these plates and they grow simultaneously. We suggest that the paradoxical growth of graphite in a hydrogen plasma, under conditions in which graphite is usually etched away, is possible because of a protective coating by a Ni-C-H phase. This thin coating allows for transport of carbon atoms from the gas phase to the growing graphite surface.

  4. Effect of Mo content on microstructure and stress-rupture properties of a Ni-base single crystal superalloy

    Directory of Open Access Journals (Sweden)

    Yunfei Liang

    2016-02-01

    Full Text Available The additional 1.5 wt% Mo was added in a Ni-base single crystal (SC alloy with the composition of Ni–6.5Al–8.0Mo–2.4Cr–6.2Ta–4.9Co–1.5Re–(0.01–0.05Y (wt% to study the effect of Mo content on the microstructure and stress-rupture properties. The creep and stress-rupture tests under the conditions of 850 °C/500 MPa and 1100 °C/130 MPa were conducted, and the microstructure of as-cast, heat treated and stress ruptured specimens were analyzed. It was found that the 1.5 wt% Mo addition enhanced the stress-rupture lives at both intermediate (850 °C and high (1100 °C temperatures. The microstructure analysis showed that adding 1.5 wt% Mo in the basic alloy affected the microstructure dramatically, i.e., the Mo-rich phases formed in the specimens of as-cast and stress-ruptured specimens. It is considered that the improvement of the stress-rupture lives is duo to the strengthening effect of Mo to both γ and γ′ phases and the decrease of stacking fault energy, diffusion constant and dislocation spacing. The Mo-rich phases precipitated under condition of 1100 °C/130 MPa did not affect the creep and stress-rupture properties obviously in the present study.

  5. Low-Cobalt Powder-Metallurgy Superalloy

    Science.gov (United States)

    Harf, F. H.

    1986-01-01

    Highly-stressed jet-engine parts made with less cobalt. Udimet 700* (or equivalent) is common nickel-based superalloy used in hot sections of jet engines for many years. This alloy, while normally used in wrought condition, also gas-atomized into prealloyed powder-metallurgy (PM) product. Product can be consolidated by hot isostatically pressing (HIPPM condition) and formed into parts such as turbine disk. Such jet-engine disks "see" both high stresses and temperatures to 1,400 degrees F (760 degrees C).

  6. Conditions Of Directional Solidification Affect Superalloy

    Science.gov (United States)

    Schmidt, D. D.; Alter, W. S.; Hamilton, W. D.; Parr, R. A.

    1992-01-01

    Report describes experiments to determine effects of gradient of temperature and rate of solidification on microstructure and fatigue properties of nickel-based superalloy MAR-M246(Hf). Enhancement of properties extends lifespans of objects, including turbo-pump blades of Space Shuttle Main Engines. Results indicate significant improvements in fatigue properties derived through manipulation of parameters of directional solidification. Particularly MAR-M246(Hf) for turbine blades contains small, well-dispersed blocky carbide and microstructure with small distances between dendrite arms, and without eutectic phase.

  7. Stress rupture properties of GH4169 superalloy

    Directory of Open Access Journals (Sweden)

    Xudong Lu

    2014-04-01

    Full Text Available GH4169 alloy is a nickel-based superalloy extensively used in the aircraft engine industry because of its excellent mechanical properties and good fabrication ability. The mechanical properties of the GH4169 at high temperature, rupture stress under severe condition deserves a close attention. In this paper, the creep rupture of the GH4169 alloy under constant load and different temperatures from 550 °C to 700 °C conditions is systematically evaluated and major impact factors in the stress rupture behavior are analyzed. Furthermore, an improving method for the alloy stress rupture is proposed.

  8. Synthesis and analysis of nickel dithiolene dyes in a nematic liquid crystal host. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports

    Energy Technology Data Exchange (ETDEWEB)

    Lippa, I. [Byron-Bergen High School, NY (United States)

    1999-03-01

    The Liquid Crystal Point Diffraction Interferometer (LCPDI) can be employed to evaluate the Omega Laser system for optimum firing capabilities. This device utilizes a nickel dithiolene infrared absorbing liquid crystal dye dissolved in a liquid crystal host medium (Merck E7). Three nickel dithiolene dyes were characterized for both their solubility in the E7 host and their infrared spectral absorption.

  9. Effect of Electromagnetic Stirring on the Quality of K417 Superalloy Ingots

    Institute of Scientific and Technical Information of China (English)

    Jin; Wenzhong; Li; Tingju; Yin; Guomao

    2007-01-01

    The effect of electromagnetic stirring on the inner quality of K417 superalloy ingots is studied with EPMA and optical microscope.The results show that while an electromagnetic stirring with 50Hz frequency and 80A current is imposed,the equiax crystals of K417 superalloy ingots can be effectively refined and increased,and the central shrinkage porosity and the dendritic segregation of K417 superalloy ingots are greatly reduced,so the inner quality of K417 superalloy ingots is obviously improved.

  10. Modelling and simulation of superalloys. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Rogal, Jutta; Hammerschmidt, Thomas; Drautz, Ralf (eds.)

    2014-07-01

    Superalloys are multi-component materials with complex microstructures that offer unique properties for high-temperature applications. The complexity of the superalloy materials makes it particularly challenging to obtain fundamental insight into their behaviour from the atomic structure to turbine blades. Recent advances in modelling and simulation of superalloys contribute to a better understanding and prediction of materials properties and therefore offer guidance for the development of new alloys. This workshop will give an overview of recent progress in modelling and simulation of materials for superalloys, with a focus on single crystal Ni-base and Co-base alloys. Topics will include electronic structure methods, atomistic simulations, microstructure modelling and modelling of microstructural evolution, solidification and process simulation as well as the modelling of phase stability and thermodynamics.

  11. Effect of Solvothermal Reduction Process on Crystal Phase of Nickel%溶剂热制备条件对镍晶体结构的影响

    Institute of Scientific and Technical Information of China (English)

    米远祝; 刘应亮; 肖勇; 袁定胜; 张静娴

    2005-01-01

    Nickel powders were obtained after chemical reduction of nickel chloride by KBH4 using absolute ethylenediamine as solvent in a stainless autoclave. The product was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD results show that the as-prepared sample have different crystal structures at different reaction temperatures. It was face-centered cubic (fcc) nickel under 200℃, and there was only hexagonal close-packed (hcp) Ni above 300℃. At 250℃, the patterns indicate that both fcc and hcp phases of Ni coexist in the as-prepared sample. When the ethylenediamine was respectively substituted by benzene and toluene, only fcc phase nickel was obtained. SEM and TEM indicate that the fcc Ni is nano-particles with about 100 nm in diameter, and hcp nickel is nano-crystalline clusters.

  12. Influences of MCrAlY coatings on oxidation resistance of single crystal superalloy DD98M and their inter-diffusion behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Long [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xin, Li, E-mail: xli@imr.ac.cn [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Xinyue; Wang, Xiaolan; Wei, Hua; Zhu, Shenglong; Wang, Fuhui [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-11-15

    Oxidation and interdiffusion behaviors of Ni-based single crystal superalloy DD98M with nominal compositions Ni–5.0Co–6.0Cr–6.3Al–6.0W–2.0Mo–6.0Ta–1.0Ti (in wt.%) and two types of MCrAlY coatings at 1000 °C and 1050 °C were investigated. Complex oxides formed on the surface of DD98M alloy when oxidized at 1000 °C and 1050 °C, which stratified, cracked and spalled. The faceted-like AlN and the particle-like and strip-like TiN formed in the alloy. The application of the NiCrAlY and NiCoCrAlYHfSi coatings greatly improved the oxidation resistance of DD98M alloy. After 500 h oxidation, α-Al{sub 2}O{sub 3} was still the dominate phase in the oxide scales formed on the coated specimens. The adhesion of the oxide scale on the NiCoCrAlYHfSi coating was much better than that on the NiCrAlY coating. Interdiffusion occurred between the coatings and the substrate, which led to the formation of the IDZ and SRZ. The IDZ of the NiCrAlY coated specimen was composed of γ phase and Al- and Ta-rich γ′ phase. The γ′ phase in the IDZ accommodated most of the inward diffusing aluminum, so the SRZ formation was suppressed when oxidized at 1050 °C. However the formation of SRZ with μ-TCP still occurred when oxidized at 1000 °C probably due to the low solubility and slow diffusion rate of the alloying elements at lower temperature. The IDZ of the NiCoCrAlYHfSi coated specimen was a single γ phase. A large amount of μ-TCP precipitated in the SRZ of the NiCoCrAlYHfSi coated specimen when oxidized at 1000 °C and 1050 °C. It can be concluded coating composition has a significant effect on the development of the IDZ and SRZ. Thermal exposure temperature also has influences on the formation of the SRZ. The mechanism of SRZ formation and TCP precipitation are discussed. - Graphical abstract: The TEM micrograph of the IDZ and SRZ of the NiCoCrAlYHfSi-coated specimen oxidized at 1050 °C for 100 h and the respective diffraction patterns of the needle-like and the

  13. Negative creep in nickel base superalloys

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter; Hald, John

    2004-01-01

    Negative creep describes the time dependent contraction of a material as opposed to the elongation seen for a material experiencing normal creep behavior. Negative creep occurs because of solid state transformations that results in lattice contractions. For most applications negative creep will h...

  14. Special Features of Creep and Long-Term Strength of Single-Crystal Refractory Nickel-Base Alloys

    Science.gov (United States)

    Semenov, S. G.; Getsov, L. B.; Tikhomirova, E. A.; Semenov, A. S.

    2016-03-01

    Results of experimental studies of creep in a wide range of temperatures and stresses are presented for three modern single-crystal nickel-base alloys. A method for determining the creep characteristics by tests including step increase of the tension is suggested and tested. The effect of transition into plastic condition on the creep parameters, the influence of the chemical composition and loading conditions on the duration of creep stages I, II and III, and the conditions of appearance of crystallographic and not crystallographic modes of fracture are analyzed. Possible simple approximations of the creep curves are considered with allowance for the accumulation of damage and occurrence of unsteady creep stages.

  15. Development and use of a new burner rig facility to mimic service loading conditions of Ni-based single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Mauget Florent

    2014-01-01

    Full Text Available Performing representative experiments of in-service operating conditions of Ni-based superalloys used as high pressure turbine blades in aeroengines is a challenging issue due to the complex environmental, mechanical and thermal solicitations encountered by those components. A new burner rig test facility called MAATRE (French acronym for Mechanics and Aerothermics of Cooled Turbine Blades has been developed at ENSMA – Pprime Institute to mimic as close as possible those operating conditions. This new test bench has been used to perform complex non-isothermal creep tests representative of thermomechanical solicitations seen by some sections of HP turbine blades during engine certification procedure.

  16. Development of a Refractory High Entropy Superalloy

    Directory of Open Access Journals (Sweden)

    Oleg N. Senkov

    2016-03-01

    Full Text Available Microstructure, phase composition and mechanical properties of a refractory high entropy superalloy, AlMo0.5NbTa0.5TiZr, are reported in this work. The alloy consists of a nano-scale mixture of two phases produced by the decomposition from a high temperature body-centered cubic (BCC phase. The first phase is present in the form of cuboidal-shaped nano-precipitates aligned in rows along <100>-type directions, has a disordered BCC crystal structure with the lattice parameter a1 = 326.9 ± 0.5 pm and is rich in Mo, Nb and Ta. The second phase is present in the form of channels between the cuboidal nano-precipitates, has an ordered B2 crystal structure with the lattice parameter a2 = 330.4 ± 0.5 pm and is rich in Al, Ti and Zr. Both phases are coherent and have the same crystallographic orientation within the former grains. The formation of this modulated nano-phase structure is discussed in the framework of nucleation-and-growth and spinodal decomposition mechanisms. The yield strength of this refractory high entropy superalloy is superior to the yield strength of Ni-based superalloys in the temperature range of 20 °C to 1200 °C.

  17. Crystal Structure and Spectroscopic Studies of Bis (morpholine dithiocarbamate) Nickel (II) Complex, Ni (C4H8ONCS2) 2

    Institute of Scientific and Technical Information of China (English)

    PAN,Su(潘苏); PAN,Su; WANG,Ying(王瑛); WANG,Ying

    2001-01-01

    The title compound has been prepared and characterized by EA, IR and TG spectralstudies. The crystal structure of nickel (IⅡ) bis(morpholine dithiocarbamate) Ni(C4HsONC S2)2 is determied by X-ray diffraction methods. It crystal lizes in the monoclinic system, space groun P2n/n, with lat tice parameters a = 0.4288(1), b = 2.0526(4), c = 0.8333(2) nn, β = 97.43(3)°, and Z = 2. In the structure, central Ni atom coordination geometry is slightly distorted square-planar with the four S atoms from two morpholine dithiocarbamate ligands. The four Ni-S bond distancs are in the range of 0.2199(5)0.2201(2) nm. The IR spectral data are in agreement with the structural ones. The TG data indicate that it decomposed completely at the 766.89°C.

  18. Helical crystallization on nickel-lipid nanotubes: perfringolysin O as a model protein.

    Science.gov (United States)

    Dang, Thanh X; Milligan, Ronald A; Tweten, Rodney K; Wilson-Kubalek, Elizabeth M

    2005-11-01

    To facilitate purification and subsequent structural studies of recombinant proteins the most widely used genetically encoded tag is the histidine tag (His-tag) which specifically binds to N-nitrilotriacetic-acid-chelated nickel ions. Lipids derivatized with a nickel-chelating head group can be mixed with galactosylceramide glycolipids to prepare lipid nanotubes that bind His-tagged proteins. In this study, we use His-tagged perfringolysin O (PFO), a soluble toxin secreted by the bacterial pathogen Clostridium perfringens, as a model protein to test the utility of nickel-lipid nanotubes as a tool for structural studies of His-tagged proteins. PFO is a member of the cholesterol dependent cytolysin family (CDC) of oligomerizing, pore-forming toxins found in a variety of Gram-positive bacterial pathogens. CDC pores have been difficult to study by X-ray crystallography because they are membrane associated and vary in size. We demonstrate that both a wild-type and a mutant form of PFO form helical arrays on nickel-lipid containing nanotubes. Cryo-electron microscopy and image analysis of the helical arrays were used to reconstruct a 3D density map of wild-type PFO. This study suggests that the use of nickel-lipid nanotubes may offer a general approach for structural studies of recombinant proteins and may provide insights into the molecular interactions of proteins that have a natural affinity for a membrane surface.

  19. Anisotropy of hydrogen diffusion in nickel single crystals: the effects of self-stress and hydrogen concentration on diffusion

    Science.gov (United States)

    Li, J.; Oudriss, A.; Metsue, A.; Bouhattate, J.; Feaugas, X.

    2017-03-01

    Hydrogen diffusion has an important role in solute-dependent hydrogen embrittlement in metals and metallic alloys. In spite of extensive studies, the complexity of hydrogen diffusion in solids remains a phenomenon that needs to be clarified. In this paper, we investigate the anisotropy of hydrogen diffusion in pure nickel single crystals using both an experimental approach and a thermodynamic development. As a first approximation, experimental data from electrochemical permeation and thermal desorption spectroscopy are described using the classical Fick’s laws and an apparent diffusion tensor. Within a thermodynamic framework, the diffusion equation can be derived from Fick’s laws with an apparent diffusion coefficient which contains an added solute content dependent term β. This term is due to the elastic strain field associated with the insertion of solute atoms. For nickel crystals, the dependence of β on the crystallographic orientation arises from the elastic anisotropy. Additionally, our results elucidate the discrepancies between the thermodynamic model and experimental observations of the effect of the solute concentration on the diffusion process. Moreover, this highlights the importance of the impact of hydrogen on vacancy formation and the subsequent consequences on the anisotropy of the apparent diffusion coefficient.

  20. Anisotropy of hydrogen diffusion in nickel single crystals: the effects of self-stress and hydrogen concentration on diffusion

    Science.gov (United States)

    Li, J.; Oudriss, A.; Metsue, A.; Bouhattate, J.; Feaugas, X.

    2017-01-01

    Hydrogen diffusion has an important role in solute-dependent hydrogen embrittlement in metals and metallic alloys. In spite of extensive studies, the complexity of hydrogen diffusion in solids remains a phenomenon that needs to be clarified. In this paper, we investigate the anisotropy of hydrogen diffusion in pure nickel single crystals using both an experimental approach and a thermodynamic development. As a first approximation, experimental data from electrochemical permeation and thermal desorption spectroscopy are described using the classical Fick’s laws and an apparent diffusion tensor. Within a thermodynamic framework, the diffusion equation can be derived from Fick’s laws with an apparent diffusion coefficient which contains an added solute content dependent term β. This term is due to the elastic strain field associated with the insertion of solute atoms. For nickel crystals, the dependence of β on the crystallographic orientation arises from the elastic anisotropy. Additionally, our results elucidate the discrepancies between the thermodynamic model and experimental observations of the effect of the solute concentration on the diffusion process. Moreover, this highlights the importance of the impact of hydrogen on vacancy formation and the subsequent consequences on the anisotropy of the apparent diffusion coefficient. PMID:28327592

  1. Influence of bis-thiourea nickel nitrate on the structural, optical, electrical, thermal and mechanical behavior of a KDP single crystal for NLO applications

    Science.gov (United States)

    Rasal, Y. B.; Shaikh, R. N.; Shirsat, M. D.; Kalainathan, S.; Hussaini, S. S.

    2017-03-01

    A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200-900 nm using UV-visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ 3) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10-5 esu and 5.57  ×  10-6 cm W-1 respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

  2. Syntheses, X-ray crystal structures, and spectroscopic properties of new nickel dithiolenes and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bigoli, F.; Pellinghelli, M.A. [Universita degli Studi di Parma (Italy); Deplano, P. [Universita degli Studi di Cagliari (Italy)] [and others

    1997-03-12

    The direct addition of nickel powder to the reaction mixtures of 1,3-dialkyl-4,5-dioxoimidazolidine-2-thione (1) with the thionation Lawesson reagent produces [Ni{sup II}(R{sub 2}timdt{sup -}){sub 2}] (R{sub 2}timdt = 1,3-dialkylmidazolidine-2,4,5-trithione). These complexes belong to a new class of nickel-dithiolenes, showing remarkably high absorption ({epsilon} {approx} 80 000 dm{sup 3} mol{sup -1} cm{sup -1}, {lambda} {approx} 1000 nm) in the near-infrared region (near-IR), accompanied by high photochemical stability that makes these complexes promising near-IR dyes.

  3. Crystal structures of two nickel compounds comprising neutral Ni(II) hydrazone complexes and di-carb-oxy-lic acids.

    Science.gov (United States)

    Nakanishi, Takumi; Sato, Osamu

    2017-02-01

    Two isostructural Ni(II) compounds, bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-chloro-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Cl2O4), and bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-bromo-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Br2O4), were synthesized and their crystal structures determined. The pair of N,N',O-tridentate N-[1-(pyridin-2-yl-κN)eth-yl]pyridine-4-carbohydrazonate L ligands result in a cis-NiO2N4 octa-hedral coordination sphere for the metal ions. The asymmetric units consist of two half-mol-ecules of the di-carb-oxy-lic acids, which are completed by crystallographic inversion symmetry. In the respective crystals, the 2,5-di-chloro-terephthalic acid (H2Cl2TPA, 1-Cl) mol-ecules form zigzag hydrogen-bonded chains with the [Ni(L)2] mol-ecules, with the hydrogen-bond distances in 1-Br slightly longer than those in 1-Cl. The packing is consolidated by aromatic π-π stacking between the di-carb-oxy-lic acid mol-ecules and terminal pyridine rings in [Ni(L)2] and short halogen-halogen inter-actions are also observed. The qualitative prediction of the H-atom position from the C-N-C angles of the terminal pyridine rings in L and the C-O distances in the carboxyl groups show that 1-Cl and 1-Br are co-crystals rather than salts.

  4. The Mechanical Properties of Candidate Superalloys for a Hybrid Turbine Disk

    Science.gov (United States)

    Gabb, Timothy P.; MacKay, Rebecca A.; Draper, Susan L.; Sudbrack, Chantal K.; Nathal, Michael V.

    2013-01-01

    The mechanical properties of several cast blade superalloys and one powder metallurgy disk superalloy were assessed for potential use in a dual alloy hybrid disk concept of joined dissimilar bore and web materials. Grain size was varied for each superalloy class. Tensile, creep, fatigue, and notch fatigue tests were performed at 704 to 815 degC. Typical microstructures and failure modes were determined. Preferred materials were then selected for future study as the bore and rim alloys in this hybrid disk concept. Powder metallurgy superalloy LSHR at 15 micron grain size and single crystal superalloy LDS-1101+Hf were selected for further study, and future work is recommended to develop the hybrid disk concept.

  5. Studying the effect of Ruthenium on High Temperature Mechanical Properties of Nickel Based Superalloys and Determining the Universal Behavior of Ruthenium at Atomic Scale with respect to alloying elements, Stress and Temperature

    Directory of Open Access Journals (Sweden)

    Sriswaroop Dasari

    2016-10-01

    Full Text Available Any property of a material is a function of its microstructure and microstructure is a function of material composition. So, to maximize the desired properties of a material, one has to understand the evolution of microstructure which in turn is nothing but the reflection of the role of alloying elements. Research has not been done to understand the universal behavior of a certain base/alloying element. Let’s take the example of Cl- ion in HCl, we all know that in general, chloride ion can only be replaced by Fluoride or oxygen ion and that no other ion can replace it. But when you consider a metal like Ni, Co, Cr, Fe etc. there is no establishment that it behaves only in a certain way. Though I concord to the fact that discovery of universal behavior of Ni is lot complex than chloride ion, I think that future research should be focused in this direction also. Superalloys are the candidate materials required to improve thermal efficiency of a gas turbine by allowing higher turbine inlet gas temperatures. Gas turbines are the heart of local power systems, next generation jet engines and high performance space rockets. Recent research in superalloys showed that addition of some alloying elements in minor quantities can result in drastic change in properties. Such an alloying element is Ruthenium (Ru. Addition of Ruthenium to superalloys has shown improvement in mechanical properties by an order of magnitude. However reasons for such improvement are not known yet. Hence, there is a need to identify its role and discover the universal behavior of ruthenium to utilize it efficiently. In this proposal, we study materials with different compositions that are derived based on one ruthenium containing superalloy, and different thermomechanical history. Based on the evolution of microstructures and results of mechanical testing, we plan to determine the exact role of Ruthenium and prediction of its behavior with respect to other elements in the material

  6. Thermomechanical fatigue and fracture characteristics of Ni-base single crystal superalloys%镍基单晶高温合金热机疲劳断裂特征

    Institute of Scientific and Technical Information of China (English)

    崔建军; 张建新; 原田广史

    2012-01-01

    为了进一步提高镍基单晶高温合金的热机疲劳性能,通过微观结构解析研究了合金热机疲劳断裂特征.通过金相和扫描电子显微镜研究了热机疲劳断裂的断口特征和微观结构.研究表明:裂纹起源于形变孪晶与试样外表面的交截处,过程中的氧化有助于裂纹的长大;裂纹尖端的应力场诱发出大量形变孪晶,而形变孪晶的存在为裂纹进一步沿着孪晶界扩展提供了便利条件;镍基单晶高温合金的疲劳断裂主要是由于形变孪晶的形成以及裂纹沿孪晶界的扩展造成的.形变孪晶与高温合金疲劳断裂密切相关.%To improve the thermomechanical fatigue(TMF) property of Ni-base single crystal superalloy,fracture characteristics of the alloy were studied through microstructural analysis.The fracture characteristics and evolution of microstructures during thermomechanical fatigue tests were acquired using optical microscope as well as scanning electron microscope.The main crack is found to originate from the intersection of deformation twin plates with specimen surface,and then oxidation assists the growth of the crack.The stress concentration at the crack tip results in high density of deformation twins and the propagation of crack along the twin boundaries can lead to TMF failure of the specimen.The fracture failure of the Ni-base single crystal superalloy is attributed to the formation of deformation twins and the propagation of crack along the twin boundaries.

  7. Optical reflectance, optical refractive index and optical conductivity measurements of nonlinear optics for L-aspartic acid nickel chloride single crystal

    Science.gov (United States)

    Anbazhagan, G.; Joseph, P. S.; Shankar, G.

    2013-03-01

    Single crystals of L-aspartic acid nickel chloride (LANC) were grown by the slow evaporation technique at room temperature. The grown crystals were subjected to Powder X-ray diffraction studies to confirm the crystal structure. The modes of vibration of different molecular groups present in LANC have been identified by FTIR spectral analysis. Optical transferency of the grown crystal was investigated by UV-Vis-NIR spectrum. The lower optical cut off wavelength for this crystal is observed at 240 nm and energy band gap 5.179 eV. The optical reflectance and optical refractive index studies have been carried out in this crystal. Finally, the optical conductivity and electrical conductivity studies have been carried out on LANC single crystal.

  8. Synthesis, Crystal Structure and Nonlinear Optical Properties of Nickel(Ⅱ) Complex with Schiff-base Ligand

    Institute of Scientific and Technical Information of China (English)

    XUE Zhao-Ming(薛照明); ZHANG Xuan-Jun(张宣军); TIAN Yu-Peng(田玉鹏); WU Jie-Ying(吴杰颖); JIANG Min-Hua(蒋民华); FUN Hoong Kun

    2003-01-01

    The nickel(Ⅱ) complex with the new ligand of S-benzyl-β-N-[10-ethylphenothiazine-3-methylene]dithiocarbazate(HL) crystallizes in the triclinic system, space group P1-with a = 7.516(1), b = 11.322(1), c = 13.366(1) (A),α= 84.818(1),β= 81.688(1), y= 76.037(1)°, V= 1090.26(3) (A)3, Z = 1, Dc=1.413 g/cm3, F(000) = 482,μ(MoKα)= 0.774 mm-1 (λ= 0.7103(A)),R = 0.0573 and wR =0.1375 for 3357 observed reflections withⅠ≥ 2σ(Ⅰ). The HL has lost a proton from its tautomeric thiol form and acts as a single negatively charged bidentate ligand coordinating to the nickel ion via the mercapto sulfur and β-nitrogen atoms. The geometry around Ni(Ⅱ) is almost square-planar with two equivalent Ni-N and Ni-S bonds. The nonlinear absorption of HL and NiL2 solutions (in DMF) was measured by open-aperture Z-scan technique at the wavelength of 532 nm.

  9. Thermochemical micro imprinting of single-crystal diamond surface using a nickel mold under high-pressure conditions

    Science.gov (United States)

    Imoto, Yuji; Yan, Jiwang

    2017-05-01

    Single-crystal diamond is an important material for cutting tools, micro electro mechanical systems, optical devices, and semiconductor substrates. However, the techniques for producing microstructures on diamond surface with high efficiency and accuracy have not been established. This paper proposes a thermochemical imprinting method for transferring microstructures from a nickel (Ni) mold onto single-crystal diamond surface. The Ni mold was micro-structured by a nanoindenter and then pressed against the diamond surface under high temperature and pressure in argon atmosphere. Results show that microstructures on the Ni mold were successfully transferred onto the diamond surface, and their depth increased with both pressure and temperature. Laser micro-Raman spectroscopy, transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) analyses indicate that a graphite layer was formed over the contact area between diamond and Ni during pressing, and after washing by a mixed acid, the graphite layer could be completely removed. This study demonstrated the feasibility of a cost-efficient fabrication method for large-area microstructures on single-crystal diamond.

  10. Misfit in Inconel-Type Superalloy

    Directory of Open Access Journals (Sweden)

    Pavel Strunz

    2013-01-01

    Full Text Available An important parameter for the characterization of microstructural changes in nickel base superalloys is the misfit - the relative difference between lattice parameters of γ matrix and γ′ precipitates. The misfit in IN738LC superalloy was examined at POLDI time-of-flight (TOF neutron diffractometer both at room temperature and in situ at elevated temperatures using a high-temperature furnace. A careful out-of-furnace measurement yielded the lattice parameters of both γ and γ′ phase at room temperature (aγ=3.58611(10 Å, aγ′=3.58857(17 Å as well as the misfit (equal to 6.9(6×10-4. The in situ measurement at elevated temperatures provided the temperature dependence of the lattice parameters of γ (up to 1120°C and γ′ (up to 1000°C. Using these data, the evolution of the misfit with temperature was calculated. The misfit decreases with increasing temperature until it reaches zero value at a temperature around 800°C. Above 800°C, it becomes negative.

  11. Phase transformation strengthening of high-temperature superalloys

    Science.gov (United States)

    Smith, T. M.; Esser, B. D.; Antolin, N.; Carlsson, A.; Williams, R. E. A.; Wessman, A.; Hanlon, T.; Fraser, H. L.; Windl, W.; McComb, D. W.; Mills, M. J.

    2016-11-01

    Decades of research has been focused on improving the high-temperature properties of nickel-based superalloys, an essential class of materials used in the hot section of jet turbine engines, allowing increased engine efficiency and reduced CO2 emissions. Here we introduce a new `phase-transformation strengthening' mechanism that resists high-temperature creep deformation in nickel-based superalloys, where specific alloying elements inhibit the deleterious deformation mode of nanotwinning at temperatures above 700 °C. Ultra-high-resolution structure and composition analysis via scanning transmission electron microscopy, combined with density functional theory calculations, reveals that a superalloy with higher concentrations of the elements titanium, tantalum and niobium encourage a shear-induced solid-state transformation from the γ' to η phase along stacking faults in γ' precipitates, which would normally be the precursors of deformation twins. This nanoscale η phase creates a low-energy structure that inhibits thickening of stacking faults into twins, leading to significant improvement in creep properties.

  12. Crack nucleation using combined crystal plasticity modelling, high-resolution digital image correlation and high-resolution electron backscatter diffraction in a superalloy containing non-metallic inclusions under fatigue.

    Science.gov (United States)

    Zhang, Tiantian; Jiang, Jun; Britton, Ben; Shollock, Barbara; Dunne, Fionn

    2016-05-01

    A crystal plasticity finite-element model, which explicitly and directly represents the complex microstructures of a non-metallic agglomerate inclusion within polycrystal nickel alloy, has been developed to study the mechanistic basis of fatigue crack nucleation. The methodology is to use the crystal plasticity model in conjunction with direct measurement at the microscale using high (angular) resolution-electron backscatter diffraction (HR-EBSD) and high (spatial) resolution-digital image correlation (HR-DIC) strain measurement techniques. Experimentally, this sample has been subjected to heat treatment leading to the establishment of residual (elastic) strains local to the agglomerate and subsequently loaded under conditions of low cyclic fatigue. The full thermal and mechanical loading history was reproduced within the model. HR-EBSD and HR-DIC elastic and total strain measurements demonstrate qualitative and quantitative agreement with crystal plasticity results. Crack nucleation by interfacial decohesion at the nickel matrix/agglomerate inclusion boundaries is observed experimentally, and systematic modelling studies enable the mechanistic basis of the nucleation to be established. A number of fatigue crack nucleation indicators are also assessed against the experimental results. Decohesion was found to be driven by interface tensile normal stress alone, and the interfacial strength was determined to be in the range of 1270-1480 MPa.

  13. Creep Behaviour of Modified Mar-247 Superalloy

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2016-06-01

    Full Text Available The paper presents the results of analysis of creep behaviour in short term creep tests of cast MAR-247 nickel-based superalloy samples made using various modification techniques and heat treatment. The accelerated creep tests were performed under temperature of 982 °C and the axial stresses of σ = 150 MPa (variant I and 200 MPa (variant II. The creep behaviour was analysed based on: creep durability (creep rupture life, steady-state creep rate and morphological parameters of macro- and microstructure. It was observed that the grain size determines the creep durability in case of test conditions used in variant I, durability of coarse-grained samples was significantly higher.

  14. Nickel Dermatitis - Nickel Excretion

    DEFF Research Database (Denmark)

    Menné, T.; Thorboe, A.

    1976-01-01

    Nickel excretion in urine in four females -sensitive to nickel with an intermittent dyshidrotic eruption was measured with flameless atomic absorption. Excretion of nickel was found to be increased in association with outbreaks of vesicles. The results support the idea that the chronic condition...... was maintained by ingestion of nickel in food....

  15. Nickel: makes stainless steel strong

    Science.gov (United States)

    Boland, Maeve A.

    2012-01-01

    Nickel is a silvery-white metal that is used mainly to make stainless steel and other alloys stronger and better able to withstand extreme temperatures and corrosive environments. Nickel was first identified as a unique element in 1751 by Baron Axel Fredrik Cronstedt, a Swedish mineralogist and chemist. He originally called the element kupfernickel because it was found in rock that looked like copper (kupfer) ore and because miners thought that "bad spirits" (nickel) in the rock were making it difficult for them to extract copper from it. Approximately 80 percent of the primary (not recycled) nickel consumed in the United States in 2011 was used in alloys, such as stainless steel and superalloys. Because nickel increases an alloy's resistance to corrosion and its ability to withstand extreme temperatures, equipment and parts made of nickel-bearing alloys are often used in harsh environments, such as those in chemical plants, petroleum refineries, jet engines, power generation facilities, and offshore installations. Medical equipment, cookware, and cutlery are often made of stainless steel because it is easy to clean and sterilize. All U.S. circulating coins except the penny are made of alloys that contain nickel. Nickel alloys are increasingly being used in making rechargeable batteries for portable computers, power tools, and hybrid and electric vehicles. Nickel is also plated onto such items as bathroom fixtures to reduce corrosion and provide an attractive finish.

  16. CCDC 1419731: Experimental Crystal Structure Determination : dodecakis(mu-2-phenylethanethiolato)-hexa-nickel dichloromethane solvate

    KAUST Repository

    Joya, Khurram S.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  17. CCDC 1419754: Experimental Crystal Structure Determination : octakis(mu2-2-phenylethanethiolato)-tetra-nickel

    KAUST Repository

    Joya, Khurram S.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  18. 一种单晶高温合金中γ'相的析出行为%The Precipitation of γ'-phase in a Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    杨旭

    2011-01-01

    研究了固溶冷却速度和时效时间对一种镍基单晶高温合金中γ'相的析出的影响.合金经1250℃固溶处理4 h.从炉中快速取出,分别进行空冷、油冷和水冷,以考察冷却速度对γ'相析出的影响.随后对固溶处理后试样进行时效处理,以考察时效时问和固溶冷却速度对γ'相长大的影响.结果表明,合金在固溶处理后,γ'相尺寸随固溶冷却速率的升高而下降.在时效处理时,γ'相尺寸的增大率随固溶冷却速度的增大而减小;随着时效时间的增加,γ'相的尺寸增加.%The effects of cooling rate and aging time on the precipitation of ,γ'-phase in a single crystal superalloy were studied. The superalloy was cooled in air, oil and water after solution heat treatment at 1 250 ℃ for 4hours ,respectively, to study the effect of cooling rate on the precipitation of γ'-phase. The solution treated samples were aging treated at 850 ℃ for 24 hours to study the effects of cooling rate and aging time on the growth of γ'-phase. The experiment results show that the size of γ'-phase decreases with the increase of cooling rate during the process of cooling. During the aging process, the size enhancement coefficient of γ'-phase increases as cooling rate decreases, and the size of γ'-phase increases with the increase of aging time.

  19. Broaching Performance of Superalloy GH4169 Based on FEM

    Institute of Scientific and Technical Information of China (English)

    Xiangwei Kong; Bin Li; Zhibo Jin; Wenran Geng

    2011-01-01

    The nickel-based superalloy GH4169 is an important material for high temperature applications in the aerospace industry. However, due to its poor machinability, GH4169 is hard to be cut and generates saw-tooth chips during high speed machining, which could significantly affect the dynamic cutting force, cutting temperature fluctuation, tool life, and the surface integrity of the parts. In this paper, the saw-tooth chip formation mechanism of superalloy GH4169 was investigated by the elasto-viscoplastic finite element method (FEM). Using the finite element software of ABAQUS/Explicit, the deformation of the part during high speed machining was simulated. The effective plastic strain, the temperature field, the stress distribution, and the cutting force were analyzed to determine the influence of the cutting parameters on the saw-tooth chip formation. The study on broaching performance has great effect on selecting suitable machining parameters and improving tool life.

  20. Microstructural Stability and Hot Deformation of γ- γ'- δ Ni-Base Superalloys

    Science.gov (United States)

    Detrois, Martin; Helmink, Randolph C.; Tin, Sammy

    2014-11-01

    Nickel-base superalloys exhibit excellent high-temperature mechanical and physical properties and remain the first choice for structural components in advanced gas turbine engines for the aerospace propulsion and power generation applications. In response to the increasing demand for more efficient solutions and tighter requirements linked to gas turbine technologies, the properties of nickel-base superalloys can be improved by modification of their thermo-mechanical and/or compositional attributes. Recent investigations have revealed the potential use of ternary eutectic γ- γ'- δ Ni-base superalloys in advanced gas turbines due to high temperature mechanical properties that are comparable to state-of-the-art polycrystalline Ni-base superalloys. With properties largely dependent on microstructural strengthening mechanisms, both the composition and thermo-mechanical processing parameters of this novel class of alloys need to be optimized concurrently. The hot deformation characteristics of four γ- γ'- δ Ni-base superalloys with varying levels of Nb were evaluated at temperatures and strain rates between 1353 K and 1433 K (1080 °C and 1160 °C) and 0.01 to 0.001/s, respectively. Evidence of dislocation-based plasticity was observed following deformation at low temperatures and high strain rates, while high temperatures and low strain rates promoted superplasticity in these alloys. The extent of the microstructural changes and the magnitude of the cavitation damage which occurred during deformation was found to vary as a function of the alloy composition.

  1. Microstructural aspects of fatigue in Ni-base superalloys.

    Science.gov (United States)

    Antolovich, Stephen D

    2015-03-28

    Nickel-base superalloys are primarily used as components in jet engines and land-based turbines. While compositionally complex, they are microstructurally simple, consisting of small (50-1000 nm diameter), ordered, coherent Ni(3)(Al,Ti)-type L1(2) or Ni(3)Nb-type DO(22) precipitates (called γ(') and γ(''), respectively) embedded in an FCC substitutional solid solution consisting primarily of Ni and other elements which confer desired properties depending upon the application. The grain size may vary from as small as 2 μm for powder metallurgy alloys used in discs to single crystals the actual size of the component for turbine blades. The fatigue behaviour depends upon the microstructure, deformation mode, environment and cycle time. In many cases, it can be controlled or modified through small changes in composition which may dramatically change the mechanism of damage accumulation and the fatigue life. In this paper, the fundamental microstructural, compositional, environmental and deformation mode factors which affect fatigue behaviour are critically reviewed. Connections are made across a range of studies to provide more insight. Modern approaches are pointed out in which the wealth of available microstructural, deformation and damage information is used for computerized life prediction. The paper ends with a discussion of the very important and highly practical subject of thermo-mechanical fatigue (TMF). It is shown that physics-based modelling leads to significantly improved life prediction. Suggestions are made for moving forward on the critical subject of TMF life prediction in notched components. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  2. Characterization of oxide scales to evaluate high temperature oxidation behavior of Ni-20Cr coated superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, H. [Mechanical Engineering Department, BBSB Engineering College, Fatehgarh Sahib 140407 (India)], E-mail: hnr97@yahoo.com; Puri, D.; Prakash, S. [Metallurgical and Materials Engineering Department, Indian Institute of Technology Roorkee, Roorkee 247 667 (India); Maiti, Rabindranath [Central Research Facilities, Indian Institute of Technology Kharaghpur, Kharaghpur (India)

    2007-08-25

    Modern thermal spray processes such as plasma spraying are usually considered to deposit high-chromium, nickel-chromium coatings onto the superalloys to enhance their high temperature oxidation resistance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni-20Cr alloy powder was deposited on three Ni-base superalloys; Superni 75, Superni 600 and Superni 601 by shrouded plasma spray process. Oxidation kinetics was established for the uncoated as well as the coated superalloys in air at 900 deg. C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. All the coated superalloys nearly followed the parabolic rate law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. The coating was found to be successful in maintaining its integrity with the superalloy substrates in all the cases. The oxide scales formed on the oxidized coated superalloys were found to be intact and spallation-free in general. The XRD analysis revealed the presence of phase like NiO, Cr{sub 2}O{sub 3} and NiCr{sub 2}O{sub 4} in the oxide scales. The XRD results were further supported by the SEM/EDAX analyses.

  3. Prediction of Larson-Miller Curve of Nickel Base Single Crystal Superalloys%镍基单晶高温合金Larson-Miller曲线的预测

    Institute of Scientific and Technical Information of China (English)

    陈志强; 韩雅芳; 钟振纲; 魏朋义; 颜鸣皋

    1999-01-01

    提出了一种预测镍基单晶高温合金Larson-Miller曲线的新方法,应用于现有镍基单晶高温合金的Larson-Miller曲线的预测.对预测的结果与试验结果进行了比较,证明该方法能够准确地预测镍基单晶高温合金的Larson-Miller曲线.

  4. Synthesis and crystal structure of dicobalt nickel orthoborate, Co{sub 2}Ni(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tekin, Berna [Department of Chemistry, Science Faculty, Balikesir University, 10145 Balikesir (Turkey)], E-mail: bbulbul@balikesir.edu.tr; Gueler, Halil [Department of Chemistry, Science Faculty, Balikesir University, 10145 Balikesir (Turkey)], E-mail: hguler@balikesir.edu.tr

    2008-03-15

    A new binary metal borate compound, dicobalt nickel orthoborate, Co{sub 2}Ni(BO{sub 3}){sub 2} has been successfully synthesized by thermally-induced solid-state chemical reaction at 900 deg. C between the initial reactants of Co(NO{sub 3}){sub 2}.6H{sub 2}O, Ni(NO{sub 3}){sub 2}.6H{sub 2}O and H{sub 3}BO{sub 3} (mol ratio 2:1:2). The product was structurally characterized by powder X-ray diffraction technique. Co{sub 2}Ni(BO{sub 3}){sub 2} crystallizes in the kotoite type and isostructural with the chemical formula M{sub 3}(BO{sub 3}){sub 2} where M = Mg, Co and Ni. Co{sub 2}Ni(BO{sub 3}){sub 2} belongs to the orthorhombic crystal system with the refined unit cell parameters of a = 5.444(8), b = 8.404(0), c = 4.504(1) A, Z = 2 and space group was determined as Pnmn. FTIR, elemental analysis and thermal analysis were also discussed in the article.

  5. Optimizing the heat treatment of Ni-based superalloy turbine discs

    Science.gov (United States)

    Furrer, D. U.; Shankar, R.; White, C.

    2003-03-01

    The heat-treatment processes for nickel-based superalloys continue to change due to the development of new alloys, new requirements, and subsequent new manufacturing facilities. Nickel-based superalloys are continuing to evolve to meet emerging applications, while new alloys are also being introduced for advanced applications. These new materials are also being optimized for numerous mechanical and physical properties, making the selection of heat-treatment parameters increasingly challenging. New processing facilities and methods are also being implemented to allow tailoring of heat-treating parameters to meet these new challenges. For example, the Ladish SuperCooler technology allows engineering and control of all aspects of the heat-treatment process for nickel-based components, resulting in never-before possible disc properties.

  6. Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes

    Science.gov (United States)

    Shafaatian, Bita; Soleymanpour, Ahmad; Kholghi Oskouei, Nasim; Notash, Behrouz; Rezvani, Seyyed Ahmad

    2014-07-01

    A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction.

  7. High temperature cyclic oxidation and hot corrosion behaviours of superalloys at 900°C

    Indian Academy of Sciences (India)

    Subhash Kamal; R Jayaganthan; S Prakash

    2010-06-01

    Oxidation and hot corrosion are serious problems in aircraft, marine, industrial, and land-base gas turbines. It is because of the usage of wide range of fuels coupled with increased operating temperatures, which leads to the degradation of turbine engines. To obviate these problems, superalloys, viz. Superni 75, Superni 718 and Superfer 800H superalloys (Midhani grade), are the prominent materials for the high temperature applications. It is very essential to investigate the degradation mechanism of superalloys due to oxidation and hot corrosion and substantiate the role of alloying elements for the formation of protective oxide films over the surface of the superalloys. Therefore, the present work investigates the oxidation and hot corrosion behaviour of superalloys exposed to air and molten salt (Na2SO4–60% V2O5) environment, respectively, at 900°C under cyclic conditions. The weight change measurements made on the superalloys during the experiments are used to determine the kinetics of oxidation and hot corrosion. X-ray diffraction (XRD), X-ray mapping and field emission scanning electron microscope (FESEM, FEI, Quanta 200F company) with EDAX Genesis software attachment, made in Czech Republic are used to characterize the corroded products of the superalloys. It is observed that the formation of scale rich in Cr2O3, NiO and spinel NiCr2O4 has contributed for the better oxidation and hot corrosion resistance of Superni 75; whereas relatively lesser hot corrosion resistance of Superfer 800H is due to the formation of non-protective oxides of iron and sulphides of iron and nickel. The parabolic rate constants calculated for the superalloys show that the corrosion rate is minimum in air as compared to molten salt environment.

  8. Perfluorodiethoxymethane on nickel and nickel oxide surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Joyce [Iowa State Univ., Ames, IA (United States)

    1994-03-03

    The interaction of perfluorodiethoxymethane with a nickel single crystal, Ni(100); a nickel crystal with chemisorbed oxygen, Ni(100)-c(2x2)O; and a nickel crystal with nickel oxide crystallites, NiO(100) is investigated in an ultra high vacuum environment using thermal desorption spectroscopy and high resolution electron energy loss spectroscopy. Nickel, a component of hard disk drives and stainless steel, is used to represent metal surfaces in these "real" systems. Perfluorodiethoxymethane is used in this study as a model compound of industrial perfluoropolyether lubricants. These lubricants are known for their exceptional stability, except in the presence of metals. Perfluorodiethoxymethane contains the acetal group (-OCF2O-), believed to be particularly vulnerable to attack in the presence of Lewis acids. Since the surfaces studied show increasing Lewis acidity at the nickel atom sites, one might expect to see increasing decomposition of perfluorodiethoxymethane due to acidic attack of the acetal group. No decomposition of perfluorodiethoxymethane is observed on the clean Ni(100) surface, while more research is needed to determine whether a small decomposition pathway is observed on the oxygenated surfaces, or whether sample impurities are interfering with results. The strength of the bonding of perfluorodiethoxymethane to the surface is found to increase as the nickel atoms sites become more acidic in moving from Ni(100) to Ni (100)-c(2x2)O to NiO (100).

  9. An anomalous small-angle X-ray scattering study on phase decomposition in a model superalloy NiCrAl

    Energy Technology Data Exchange (ETDEWEB)

    Bley, F.; Livet, F.; Simon, J.P. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Grenoble (France). Lab. de Thermodynamique et Physico-Chimie Metallurgiques; Lyon, O.; Okuda, H.

    1998-12-01

    The precipitation structure in a model nickel-based superalloy was examined by using anomalous X-ray small-angle scattering. Preliminary results are presented on the temporal power law of the precipitation growth and the partitioning of the solute atoms between the precipitates and the matrix. In the present experiment, the concentration of nickel was the same in the matrix and the precipitates, giving no contrast change near the nickel K edge. (orig.). 7 refs.

  10. Atomistic simulation of martensite-austenite phase transition in nanoscale nickel-titanium crystals

    Science.gov (United States)

    Kexel, Christian; Schramm, Stefan; Solov'yov, Andrey V.

    2015-09-01

    Shape-memory (SM) alloys can, after initial inelastic deformation, reconstruct their pristine lattice structure upon heating. The underlying phenomenon is the structural solid-solid phase transition from low-temperature lower-symmetry martensite to the high-temperature higher-symmetry austenite. Conventional nickel-titanium (NiTi) with near-equiatomic concentration already possesses an eminent importance for many applications, whereas the nanostructured equivalent can exhibit yet enhanced thermomechanical properties. However, no plausible microscopic theory of the SM effect in NiTi exists, especially for nanoscale systems. We investigate the thermally induced martensite-austenite phase transition in free equiatomic nanocrystals, comprising up to approximately 40 000 atoms, by means of molecular-dynamics simulations (MD) using a classical Gupta-type many-body scheme. Thereby we complement and extend a previously published study [D. Mutter, P. Nielaba, Eur. Phys. J. B 84, 109 (2011)]. The structural transition, revealing features of a first-order phase transition, is demonstrated. It is contrasted with the melting phase transition, a quantum solid model and bulk experimental findings. Moreover, a nucleation-growth process is observed as well as the irreversibility of the transition upon cooling.

  11. DD6单高温合金热处理过程中的再结晶组织演化%Microstructural Evolution of Recrystallization DuringHeat Treatment in DD6 Single Crystal Superalloy

    Institute of Scientific and Technical Information of China (English)

    曲彦平; 刘丽荣; 祖国庆; 金涛; 胡壮麒

    2011-01-01

    研究DD6单晶高温合金塑性变形后热处理过程中的组织演化.结果表明,1500kg加载后,在铸态γ’相溶解温度以下预处理没有再结晶现象,预处理后再进行固溶处理发生明显的再结晶;γ’相溶解温度以上预处理发生明显的再结晶,再结晶晶界细小,晶界由粗大γ’相组成.与固溶态相比,时效处理后的再结晶深度变化不大,时效过程中,晶界由固溶态的窄晶界变为宽大的胞状晶界,并且有粒状M6C碳化物沿晶界析出.%Microstructural evolution of recrystallization during heat treatment in DD6 single crystal su-peralloy were investigated. The results showed that during pre-treatment at the temperature up to as-cast γ' phase solvus, no recrystallization occurred, while after solution treatment, rapid recrystallization occurred. During preheat treatment above the temperature, recrystallization occurred. The recrystallization grain boundary was thin and composed of bigger γ' phase. Compared with the micro-structure after solution treatment, the recrystallization depth after aging treatment had no obvious change. During aging treatment, grain boundary turned into wider cellular structure and some granular M6C carbide precipitated from grain boundary.

  12. Crystal Structure and Characterization of 2-N-(2-Hydroxy-benzylidene) Furanmethanoamine Nickel(Ⅱ) Complex

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; XU Hong; ZHOU Hua; WEI Ping

    2005-01-01

    The Ni(Ⅱ) complex with ligand 2-N-(2-hydroxy-benzylidene) furanmethanoamine has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction.It crystallizes in the monoclinic system, space group C2/c with a = 2.0280(4), b =0.57700(12), c = 1.7340(4) nm, β = 94.74(3)°, Z = 4, Dc = 1.508 g/cm3, the final R = 0.0434 and wR = 0.1112 for 1843 observed reflections with I > 2σ(I).X-ray analysis revealed that the Ni(Ⅱ)ion is coordinated by two nitrogen atoms of Schiff base and two oxygen atoms of salicylaldehyde in the equatorial plane, and the coordination geometry can be described as a square.

  13. Influence of plastic strain on the hydrogen evolution reaction on nickel (100) single crystal surfaces to improve hydrogen embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Lekbir, C., E-mail: choukri.lekbir@univ-lr.fr; Creus, J.; Sabot, R.; Feaugas, X.

    2013-08-20

    Hydrogen-induced embrittlement can be accountable for premature failure of structure in relation with physical and/or chemical processes occurring on material's surface or in the bulk of the material. Hydrogen Evolution Reaction (HER) corresponding to the early step of hydrogen ingress in the material is explored in present study in relation with plastic strain. HER on nickel (100) single crystal in sulphuric acid medium can be related by a Volmer–Heyrovsky mechanism. The corresponding elementary kinetic parameters as symmetry coefficients, activation enthalpies, and number of active sites have been identified via a thermokinetic model using experimental data. These parameters can be affected by defects associated with plastic strain. Irreversible plastic strain modifies the density and the distribution of storage dislocations affecting the surface roughness at atomic scale and generating additional active adsorption sites. Furthermore, surface emergence of mobile dislocations induces the formation of slip bands, which modify the surface roughness and the electronic state of the surface and increases the (111) surface density. The consequence of plastic strain on HER is explored and discussed in relation with both processes.

  14. Synthesis, crystal structures and properties of two novel macrocyclic nickel(II) and copper(II) complexes

    Science.gov (United States)

    Su, Yan-Hui; Liu, Jie; Li, Jia; Si, Xue-Zhi

    2007-06-01

    Two new 14-membered hexaaza macrocyclic complexes with the formulae [NiL](ClO 4) 2·CH 3COCH 3 ( 1) and [CuL](ClO 4) 2·CH 3COCH 3 ( 2), where L = 3,10-bis(2-thiophenemethyl)-1,3,5,8,10,12-hexaazacyclotetradecane, have been synthesized and characterized by elemental analyses, single-crystal X-ray diffraction analyses, electronic spectra, IR and TG-DTA. In 1, the nickel(II) ion is four-coordinated with four nitrogen atoms from the macrocycle and forms a square-planar coordination geometry. In 2, the copper(II) ion is six-coordinated with four nitrogen atoms from the macrocyclic ligand in the equatorial plane and two oxygen atoms from the perchlorate anions in the axial position exhibiting an elongated octahedron coordination geometry. The two complexes present two different molecular arrangements in which the [ML] 2+ (M = Ni, Cu) cation arrays in the manner of M(1)M(2)M(1)… in sequence. The pendant thiophene groups of the neighboring macrocycles have no π⋯π interactions. All the ClO4- anions and acetone molecules are involved in hydrogen-bonding interactions with the macrocyclic ligand.

  15. Synthesis,Crystal Structure and Thermal Stability of(Diacetylacetone)(diimidazole)Nickel(Ⅱ)Complex

    Institute of Scientific and Technical Information of China (English)

    建方方; 庞蕾; 肖海连; 孙萍萍

    2004-01-01

    The title compound, [Ni(acac)2(Im)2] (acac = acetylacetone), has been obtained by the reaction of Ni(acac)2 with imidazole ligand in the ethanol solvent. The blue crystal is of triclinic, space group Pī with a = 7.472(2), b = 9.456(2), c = 13.823(3)A, α = 85.55(3), β = 89.03(3), γ = 80.63(3)o, C16H22N4NiO4, Mr = 393.09, V = 960.7(3)A3, Z = 2, Dc = 1.359 g/cm3, F(000) = 412, μ = 1.036 mm-1, R = 0.0549 and wR = 0.1615. The crystal structure consists of two disconnected structural units. Each Ni atom coordinated by two N atoms from two imidazole ligands and four O atoms from two acetylactone ligands adopts a slightly distorted octahedron. The structure characterization was performed by means of IR, UV, TG, elemental analysis and single-crystal X-ray analysis. The thermal gravity (TG) data indicate that thermal decomposition of the title compound takes place in two steps, and the residue is NiO.

  16. Processing-structure characterization of rheocast IN-100 superalloy

    Science.gov (United States)

    Cheng, Jung-Jen Allen; Apelian, Diran; Doherty, Roger D.

    1986-11-01

    The rheocasting solidification process has been applied in the production of IN-100 nickel base superalloy. A high vacuum furnace for rheocasting superalloys was used to rheocast ingots under different processing conditions. Processing variables which were evaluated include stirring speed, isothermal stirring time, and volume fraction solid during isothermal stirring. Ingots, furnace cooled at the same rate but without stirring, were also examined for comparison with the rheocast ingots. A detailed microstructural examination was made of the resultant microstructure both on furnace cooling after stirring and on reheating to the isothermal stirring temperature followed by water quenching. Rheocasting yielded fine-grained structures, where the extent of microsegregatiori, the variation in macrostructure, and the solidification-induced porosity were found to be reduced in comparison to the unstirred ingot. The grain size and nonuniformity in the as-cast ingot were reduced by increasing the stirring speed, isothermal stirring time, or the volume fraction solid during stirring. The degree of the microsegregation decreased significantly with increasing volume fraction solid. Grain boundaries, both with and without solute enrichment, were found in the rosette-like solid particles after rheocasting, lending support to the Vogel-Cantor-Doherty model of rheocasting based on the formation of grain boundaries by strain-induced recrystallization and by sintering. It is clear from these results that the microstructure of this superalloy was significantly improved by rheocasting. Improved mechanical properties were also found and will be reported separately.

  17. A Comparison of the Plastic-Flow Response of a Powder-Metallurgy Nickel-Base Superalloy Under Nominally-Isothermal and Transient-Heating Hot-Working Conditions

    Science.gov (United States)

    Semiatin, S. L.; Mahaffey, D. W.; Tung, D. J.; Zhang, W.; Senkov, O. N.

    2017-01-01

    The flow-stress behavior at hot-working temperatures and strain rates of the powder-metallurgy superalloy LSHR was determined under nominally-isothermal and transient-heating conditions. Two conventional methods, compression of right-circular cylinders and torsion of thin-walled tubes, were used for isothermal tests. A direct-resistance-heating technique utilizing torsion of round-bar specimens in a Gleeble® machine was applied for both isothermal and transient-heating conditions. When expressed in terms of effective stress and strain, baseline data determined by the two conventional methods showed good agreement. With the aid of a flow-localization analysis to assess the confounding influence of axial (and radial) temperature gradients on deformation uniformity, the flow stresses determined from nominally-isothermal Gleeble® torsion tests were shown to be broadly similar to those from the conventional tests. With regard to transient phenomena, Gleeble® tests were also useful in quantifying the effect of rapid heating and short soak time on the observed higher flow stress associated with a metastable microstructure. The present work also introduces two new test techniques using direct-resistance-heated torsion specimens. One involves continuous heating under constant-torque conditions, and the other comprises testing an individual specimen at a series of temperatures and strain rates. Using a single specimen, the former method enabled the determination of the apparent activation energy for plastic flow, which was similar to that determined from the series of isothermal tests; the latter provided a low-cost, high-throughput approach to quantify the flow behavior.

  18. A Comparison of the Plastic-Flow Response of a Powder-Metallurgy Nickel-Base Superalloy Under Nominally-Isothermal and Transient-Heating Hot-Working Conditions

    Science.gov (United States)

    Semiatin, S. L.; Mahaffey, D. W.; Tung, D. J.; Zhang, W.; Senkov, O. N.

    2017-04-01

    The flow-stress behavior at hot-working temperatures and strain rates of the powder-metallurgy superalloy LSHR was determined under nominally-isothermal and transient-heating conditions. Two conventional methods, compression of right-circular cylinders and torsion of thin-walled tubes, were used for isothermal tests. A direct-resistance-heating technique utilizing torsion of round-bar specimens in a Gleeble® machine was applied for both isothermal and transient-heating conditions. When expressed in terms of effective stress and strain, baseline data determined by the two conventional methods showed good agreement. With the aid of a flow-localization analysis to assess the confounding influence of axial (and radial) temperature gradients on deformation uniformity, the flow stresses determined from nominally-isothermal Gleeble® torsion tests were shown to be broadly similar to those from the conventional tests. With regard to transient phenomena, Gleeble® tests were also useful in quantifying the effect of rapid heating and short soak time on the observed higher flow stress associated with a metastable microstructure. The present work also introduces two new test techniques using direct-resistance-heated torsion specimens. One involves continuous heating under constant-torque conditions, and the other comprises testing an individual specimen at a series of temperatures and strain rates. Using a single specimen, the former method enabled the determination of the apparent activation energy for plastic flow, which was similar to that determined from the series of isothermal tests; the latter provided a low-cost, high-throughput approach to quantify the flow behavior.

  19. Barium iron arsenide, barium cobalt arsenide, barium nickel arsenide single crystals and superconductivity upon cobalt doping

    Energy Technology Data Exchange (ETDEWEB)

    Ronning, Filip [Los Alamos National Laboratory; Sefat, A S [ORNL; Mcguire, M M [ORNL; Sales, B [ORNL; Jin, R [ORNL; Mandrus, D [ORNL

    2009-01-01

    The crystal structure and physical properties of BaFe{sub 2}As{sub 2}, BaCo{sub 2}As{sub 2}, and BaNi{sub 2}As{sub 2} single crystals are surveyed. BaFe{sub 2}As{sub 2} gives a magnetic and structural transition at T{sub N} = 132(1) K, BaCo{sub 2}As{sub 2} is a paramagnetic metal, while BaNi{sub 2}As{sub 2} has a structural phase transition at T{sub 0} = 131 K, followed by superconductivity below {Tc} = 0.69 K. The bulk superconductivity in Co-doped BaFe{sub 2}As{sub 2} below {Tc} = 22 K is demonstrated by resistivity, magnetic susceptibility, and specific heat data. In contrast to the cuprates, the Fe-based system appears to tolerate considerable disorder in the transition metal layers. First principles calculations for BaFe{sub 1.84}Co{sub 0.16}As{sub 2} inter-band scattering due to Co is weak.

  20. SUPERPLASTICITY AND DIFFUSION BONDING OF IN718 SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1 ×10-4s-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T,pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are: T= 1273-1323K, p = 20-30MPa, t = 45-60min.

  1. Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Osoba, L.O. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada); Ding, R.G. [Department of Metallurgy and Materials Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Ojo, O.A., E-mail: ojo@cc.umanitoba.ca [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, Manitoba, R3T 5V6 (Canada)

    2012-03-15

    Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti-Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with the formation of {gamma}-{gamma}' eutectic in {gamma}' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: Black-Right-Pointing-Pointer A newly developed superalloy was welded by CO{sub 2} laser beam joining technique. Black-Right-Pointing-Pointer Electron microscopy characterization of the weld microstructure was performed. Black-Right-Pointing-Pointer Identified interdendritic microconstituents consist of MC-type carbides. Black-Right-Pointing-Pointer Modification of primary solidification path is used to explain cracking resistance.

  2. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    Science.gov (United States)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  3. Synthesis, spectral (IR, UV-Vis and variable temperature NMR) characterization and crystal structure of (N-benzyl-N-furfuryldithicarbamato-S,S')(thiocyanato-N)(triphenylphosphine)nickel(II).

    Science.gov (United States)

    Valarmathi, P; Thirumaran, S; Sarmal, Lovely; Kant, Rajni

    2014-08-14

    Planar (N-benzyl-N-furfuryldithiocarbamato-S,S')(thiocyanato-N)(triphenylphospine)nickel(II), [Ni(bfdtc)(NCS)(PPh3)], (1) was prepared from bis(N-benzyl-N-furfuryldithiocarbamato-S,S')nickel(II), [Ni(bfdtc)2], (2) and characterized by elemental analysis, cyclic voltammetry, electronic, IR and variable temperature (1)H and (13)C NMR spectra. For complex 1, the thioureide vCN value is shifted to higher wavenumber compared to 2 and N(13)CS2 carbon signal observed for 1 is additionally shielded compared to the parent complex 2, suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. In the room temperature (13)C NMR spectrum of 1, two pseudo doublets are observed in the aliphatic region. Variable temperature (13)C NMR spectral studies suggest that the fast thiocyanate exchange appears to be responsible for the appearance of pseudo doublets. Single crystal X-ray structural analysis of 1 and 2 confirm the presence of four coordinated nickel in a distorted square planar arrangement with the NiS2PN and NiS4 chromophores, respectively. The NiS bonds are symmetric in 2 (2.1914(14) and 2.2073(13)Å). But significant asymmetry in NiS bond distances was observed in 1 (2.2202(8)Å and 2.1841Å). This observation clearly supports the less effective trans effect of SCN(-) over PPh3. Cyclic voltammetric studies revealed easier reduction of nickel(II) to nickel(I) in complex 1 compared to 2.

  4. FGH95镍基合金组织结构对持久性能的影响%Influence of microstructure on enduring properties of FGH95 nickel-base superalloy

    Institute of Scientific and Technical Information of China (English)

    谢君; 田素贵; 周晓明; 李柏松

    2012-01-01

    通过对不同温度热等静压FGH95合金进行完全热处理、组织形貌观察、XRD谱线分析及持久性能测试,研究FGH95合成组织结构对持久性能的影响,结果表明:随着HIP温度升高,分布在原始颗粒边界处的粗大γ’相数量和尺寸逐渐减小,当HIP温度提高至1 180℃,晶粒明显长大.热等静压合金经完全热处理后,粒状碳化物沿晶界和晶内不连续分布,且细小γ'相在基体中弥散析出.经X线衍射分析,随热等静压温度升高,γ和γ'两相晶格常数略有增加,但错配度逐渐减小;在650℃,1 034 MPa条件下,由于1 120℃HIP合金完全热处理后具有较高的晶格错配度,致使合金具有较长持久寿命;合金在蠕变期间的变形特征是位错滑移,位错绕过或剪切γ'相.%By means of full heat treatment, microstructure observation, XRD diffraction analysis and enduring properties measurement, an investigation was made into the influence of microstructure on enduring properties of FGH95 superalloys. The results show that the quantities and size of the coarser γ' phase distribute in the regions decrease as the HIP temperature increases. With the HIP temperature increases to 1 180 ℃, the grain obviously grows up. After the HIP alloy is fully heat treated, the carbide particles discontinuously distribute along boundaries and in the grain, and the fine γ’ phase dispersedly precipitates in the matrix. After X-ray diffraction analysis, the lattice parameters of γ and γ’ phase increase slightly, but the misfit decreases gradually. Under the condition of 650 ℃ and 1 034 MPa, as the 1 120 ℃ HIP alloy which is fully heat treated has higher lattice misfit, the alloy possesses longer lifetime. During creep process, the deforming features of the alloy are dislocations slipping in the matrix, dislocations crossing or shearing into γ’ phase.

  5. Synthesis and Crystal Structure of Binuclear and Pentanuclear Nickel(II Complexes Containing 4-(salicylaldiminatoantipyrine Schiff base

    Directory of Open Access Journals (Sweden)

    Mohamed N. EL-Kaheli

    2015-11-01

    Full Text Available The new title binuclear Ni (II compound  (1 and the novel pentanuclear Ni (II cluster {[   } (2 are formed from the reaction of an asymmetric Schiff base ligand L (L = 4-(salicylaldiminatoantipyrine with Ni .4  in the former or Ni(ClO42.6H2O in presence of malonate in the later.  Complex (1 consists of ( ]+ cation and one uncoordinated tetraphenylborate anion.  The cation adopts a distorted octahedral arrangement around each metal center.  In the binuclear unit both Ni(II ions are linked through two phenolate (µ2-O oxygen atoms of L, and two oxygen atoms of a  bridging carboxylate group. Each Ni (II coordinates to four oxygen atoms at the basal plane, two oxygen atoms from two bridging phenolate groups, one from pyrazolone ring and the last of an aqua molecule, and at the axial positions to a bridging carboxylate-O atom and an azomethine nitrogen atom.  In the pentanuclear cluster (2 consisting of [ ]+2 cation and two tetraphenylborate anions, the core of the cation is assembled by four [Ni( ] units, linked to the central Ni-ion by two bridging water molecules. The resulting coordination sphere for the external symmetry related nickel ions is a pseudo octahedron.  The central Ni-atom unusually adopts dodecahedron geometry through its coordination to eight bridging water molecules. In complex (1 each Ni-atom is coordinated to one tridentate L ligand and in complex (2 each [Ni ( ] unit is coordinated to two bidentate L ligands.  Inter-and intramolecular hydrogen bonds are present in both crystal structures.

  6. Crystal Structures and Antifungal Activities of Fluorine-Containing Thioureido Complexes with Nickel(II

    Directory of Open Access Journals (Sweden)

    Chun Li

    2013-12-01

    Full Text Available Ni(II complexes with N-2-fluorobenzoylpiperidine-1-carbothioimidate (L2−, N-4-fluorobenzoylpiperidine-1-carbothioimidate (L3−, N-2-fluorobenzoylmorpholine- 1-carbothioimidate (L5− and N-4-fluorobenzoylmorpholine-1-carbothioimidate (L6−  have been synthesized and characterized by elemental analysis, FTIR and 1H-NMR. The crystal structures of three ligands (HL2, HL3 and HL6 and the corresponding Ni(II complexes ([Ni(L22], [Ni(L32] and [Ni(L62] have been determined by X-ray diffraction. The antifungal activities of the Ni(II complexes together and the corresponding ligands against the fungi Botrytis cinerea, Trichoderma spp., Myrothecium and Verticillium spp. have been investigated. The experimental results showed that the ligands and their complexes have antifungal abilities. When the fluorine was substituted on the para-benzoyl moiety, the antifungal activity of the ligands was obviously increased. Moreover, the ligands were stronger than their complexes in inhibiting fungal activities. The antifungal ability of HL6 is especially strong, and similar to that of the commercial fungicide fluconazole.

  7. Towards low-friction and wear-resistant plasma sintering dies via plasma surface co-alloying CM247 nickel alloy with V/Ag and N

    OpenAIRE

    Zhang Zhenxue; Li Xiaoying; Dong Hanshan; Sánchez Eluxka Almandoz; Fuentes Gonzalo García; Qin Yi

    2015-01-01

    Nickel based superalloys have good oxidation and creep resistance and hence they can function under high mechanical stress and high temperatures. However, their undesirable tribological behaviour is the major technical barrier to the challenging high-temperature, lubricant-free plasma sintering tool application. In this study, nickel based CM247 superalloy surfaces were co-alloyed using innovative active screen plasma technology with both interstitial element (e.g. N) and substitutional alloy...

  8. Stem-EDX and FIB-SEM Tomography of ALLVAC 718Plus Superalloy

    Directory of Open Access Journals (Sweden)

    Kruk A.

    2016-06-01

    Full Text Available Allvac 718Plus (718Plus is a high strength, corrosion resistant nickel- based superalloy used for application in power generation, aeronautics and aerospace industry. The 718Plus microstructure consists of a γ matrix with γ’-Ni3(Al,Ti and some δ- Ni3Nb phases as well as lamellar particles (η-Ni3Ti, η*-Ni6AlNb or Ni6(Al,TiNb precipitated at the grain boundaries.

  9. HIGH-TEMPERATURE LOW CYCLE FATIGUE BEHAVIOR OFNICKEL BASE SUPERALLOY GH536

    Institute of Scientific and Technical Information of China (English)

    M. Zhao; L.Y. Xu; K.S. Zhang; B.Y. Yang

    2001-01-01

    Low cycle fatigue tests on nickel base superalloy GH536 were performed at 600. 700and 800°C. The strain-life and cyclic stress-strain relationship were given at various temperatures. The change in fatigue life behavior and fatigue parameters with temperature increasing was discussed. At low and intermediate total strain amplitudes,the fatigue life was found to decrease with increasing temperature.``

  10. Oxidation resistant iron and nickel alloys for high temperature use

    Science.gov (United States)

    Hill, V. L.; Misra, S. K.; Wheaton, H. L.

    1970-01-01

    Iron-base and nickel-base alloys exhibit good oxidation resistance and improved ductility with addition of small amounts of yttrium, tantalum /or hafnium/, and thorium. They can be used in applications above the operating temperatures of the superalloys, if high strength materials are not required.

  11. Aspectos metalúrgicos de revestimentos dissimilares com a superliga à base de níquel inconel 625 Metallurgical aspects of dissimilar weld overlays of inconel 625 nickel based superalloys

    Directory of Open Access Journals (Sweden)

    Cleiton Carvalho Silva

    2012-09-01

    Full Text Available Prolongar a vida útil e aumentar a confiabilidade de equipamentos e tubulações de plantas de produção e processamento de petróleo é uma busca constante no setor de petróleo e gás. Tais aspectos dependem essencialmente do uso de ligas resistentes à corrosão. Neste contexto, a soldagem de revestimento com superligas à base de níquel tem sido uma alternativa interessante, pois confere aos equipamentos uma alta resistência à corrosão com um custo inferior, se comparado à fabricação de componentes ou tubulações maciças com superligas. Assim, o objetivo do presente trabalho foi investigar o comportamento metalúrgico de revestimento de superliga à base de níquel do tipo Inconel 625 depositados pelo processo TIG com alimentação de arame frio. As soldagens foram realizadas em uma bancada robotizada, empregando uma fonte eletrônica de soldagem com sistema de aquisição de dados para o monitoramento dos sinais de corrente e tensão. A caracterização microestrutural foi realizada através das técnicas de microscopia eletrônica de varredura (MEV e transmissão (MET, espectroscopia de energia dispersiva de raios-X (EDS. Os resultados mostraram que a microestrutura do metal de solda foi constituída por uma matriz γ com fases secundárias ricas em Nb. Foi encontrada a formação de precipitados complexos de carbonetos/nitretos de Ti e Nb.To extend the life and reliability of pipes and equipment in oil & gas production and processing settings is a continuous demand. These aspects are essentially dependent on corrosion resistant alloys used. In this context, the weld overlay with Ni-based superalloys is a great interesting alternative, since improve the corrosion resistance without increase the cost of manufacture when compared to massive equipment. Thus, the objective of this study was to evaluate the metallurgical aspects of Inconel 625 weld overlays deposited by GTAW cold wire feed process. The welds were performed using a

  12. NICKEL-BASED ALLOYS IN GE AIRCRAFT TURBINES:PAST,PRESENT & FUTURE

    Institute of Scientific and Technical Information of China (English)

    D. Chang; R. Schafrik

    2005-01-01

    Improvements in materials have been critical to advances in the propulsion system. Over the past 50 years, many improvements have been made to nickel-based superalloys to satisfy design requirements; several key developments will be highlighted. Today, millions of pounds of superalloys are annually produced for use in turbine blades, vanes, disks, cases, and frames throughout the engine. Looking to the future, several themes emerge, although predicting the future is inherently risky.

  13. Evaluation of powder metallurgy superalloy disk materials

    Science.gov (United States)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  14. Nickel Electroplating

    Institute of Scientific and Technical Information of China (English)

    Toru Murakami; Yasuo Uchikoshiki; Kazutoshi Komori

    2004-01-01

    Nickel electroplating has been used practically for decades, is easy to plate, but there is an unknown interest in it.Nickel electroplating as a basis of surface treatment is shown practically from basics to the applied electronics use. At first the basics of nickel electroplating, for example, purpose, use, merit & demerit, nickel plating solution, current efficiency,limiting current density, additional agents and their behaviors are surveyed. And the points of nickel deposition already practically used such as decorative nickel plating, satin nickel plating and functional nickel plating, which has very high throwing power and has been used for electronics, are described in detail.

  15. Nickel Electroplating

    Institute of Scientific and Technical Information of China (English)

    ToruMurakami; YasuoUchikoshiki; KazutoshiKomori

    2004-01-01

    Nickel electroplating has been used practically for decades, is easy to plate, but there is an unknown interest in it. Nickel electroplating as a basis of surface treatment is shown practically from basics to the applied electronics use. At first the basics of nickel electroplating, for example, purpose, use, merit & demerit, nickel plating solution, current efficiency, limiting current density, additional agents and their behaviors are surveyed. And the points of nickel deposition already practically used such as decorative nickel plating, satin nickel plating and functional nickel plating, which has very high throwing power and has been used for electronics, are described in detail.

  16. Strain-induced γ{sup '}-coarsening during aging of Ni-based superalloys under uniaxial load. Modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mushongera, Leslie T.

    2016-07-28

    Turbine blades which are used in the hot paths of aerospace or industrial gas turbines are usually manufactured as casted single crystalline parts. However, even though grain boundaries are excluded, the degradation behavior of respectively developed single crystal nickel-base superalloys, is still quite complex involving a number of very different microscopic effects. One of these is the diffusion-limited coarsening of the γ{sup '}-precipitates. Long-term aging or creep loading along the <100> crystallographic orientation results in the anisotropic coarsening of the γ{sup '}-precipitates. In the end, the microstructure contains quite large, irregularly shaped precipitates or plate-like precipitates aligned either parallel (P-type rafts) or perpendicular (N-type rafts) to the loading direction. This behavior is detrimental for the properties of these materials since their superior properties emanate from the size, morphology and distribution of the γ{sup '}-precipitates [R. Reed: Cambridge University Press, (2006)]. In order to efficiently design these materials, the phenomenon of coarsening should be known in detail to optimize the materials accurately. On this background, the general objective of this thesis is to develop an integrated computational approach for simulating morphological evolution in single crystal Ni-base superalloys. As a first step towards that aim, a multi-component phase field model coupled to inputs from CALPHAD-type and kinetic databases for the relevant driving forces was developed based on the grand-potential formalism similar to Plapp [Phys. Rev. E, 84: 031601 (2011)]. The thermodynamic formulation of the model was validated by comparisons to ThermoCalc equilibrium calculations and DICTRA sharp-interface simulations. Phase field approaches that allow for anisotropies of the interfacial energy sufficiently high so that the interface develops sharp corners due to missing crystallographic orientations were formulated. This

  17. Evaluation of hot corrosion behaviour of HVOF sprayed NiCrAl coating on superalloys at 900 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Mahesh, R.A. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India); Jayaganthan, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)], E-mail: rjayafmt@iitr.ernet.in; Prakash, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, IIT Roorkee Campus, Roorkee 247667, Uttarakhand (India)

    2008-10-15

    In the present investigation, NiCrAl coating was deposited on Ni- and Fe-based superalloy substrates by using high velocity oxy-fuel (HVOF) process to study the hot corrosion behaviour in molten salt (Na{sub 2}SO{sub 4}-60% V{sub 2}O{sub 5}) environment at 900 deg. C under cyclic conditions. The mass gain measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopic analysis (SEM/EDS) and X-ray mapping techniques were used to analyse the corrosion products. The bare superalloys experienced higher weight gain. The NiCrAl-coated Superni 750 alloy (SN 750) provided a better protection among the coated superalloys investigated. The formation of oxides and spinels of nickel, chromium and aluminum may be contributing better resistance to hot corrosion.

  18. Pulsed laser-assisted machining of Inconel 718 superalloy

    Science.gov (United States)

    Azhdari Tadavani, Soheila; Shoja Razavi, Reza; Vafaei, Reza

    2017-01-01

    Nickel-based superalloys including Inconel 718(IN718) are widely used in aerospace industries due to their superior high temperature strength, toughness, and corrosion resistance. These alloys are difficult to machine mainly because of their low thermal conductivity and high work hardening rate, which cause steep temperature gradient and high cutting forces at the tool edge. The application of laser assisted machining is the subject of many new researches since shear forces; surface coarsening and tool wear are reduced. The aim of this investigation was to evaluate laser assisted machining behavior of a 718 Inconel superalloy from the view point of machining specific energy, surface roughness, tool wear and chip appearance. Experimental apparatuses used included optical and scanning electron microscopy, spark emission spectroscopy, and EDS analysis. The results indicated that increasing the temperature to about 540 °C just ahead of primary shear zone, can result in 35% reduction of machining specific energy, in comparison with conventional machining. Furthermore, surface coarsening and tool wear were reduced by 22% and 23% respectively. Flank wear was the main deteriorating factor on cutting tools during laser assisted machining. SEM micrographs indicated that increase in temperature has no noticeable effect on finished workpiece surface. Analysis of variance obtained from regression analysis indicated that frequency of laser beam has the most influential effect on temperature. The optimum conditions for laser assisted machining of 718 superalloy is suggested as follows: 80 Hz frequency, 400 W power, 24 m/min cutting speed, and 0.052 mm/rev feed rate along with 540 °C temperature, 2.51 J/mm2 machining specific energy and 130 N cutting force.

  19. Tuning crystal phase of NiSx through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction

    Science.gov (United States)

    Li, Xiao; Shang, Xiao; Rao, Yi; Dong, Bin; Han, Guan-Qun; Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-02-01

    A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiSx/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). XRD patterns confirm the composition of NiSx/NF(Ox): two kinds of crystal phase including β-NiS and Ni3S2. While using bare NF as support under identical conditions, only Ni3S2 phase can be detected. SEM images reveal two kinds of morphologies of NiSx/NF(Ox) including pyramids structure of β-NiS and nanorod-like structure of Ni3S2, which implies the tuning effect of electro-pretreatment of NF on the selective preparation of NiSx crystal phase. It can be speculated that Ni(OH)2 layer derived from electro-oxidized NF is responsible for the growth of β-NiS while metallic Ni is transformed into Ni2S3 during sulfurization. Electrochemical measurements for OER indicate the enhanced electrocatalytic activity of NiSx/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm-2 compared with Ni3S2/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of β-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiSx crystal phases for preparing excellent OER eletrocatalysts.

  20. Application of Rapidly Solidified Superalloys.

    Science.gov (United States)

    1977-11-01

    those described earlier. It was noted, however, that the conventional lype stlperalloys (as evidenced in MAR M2(W, AF2-1DA and MAR M247 alloys, the...Activation Energy For Matrix Creep in MAR MAX() Alloy....................... I I *v 7o- SUMMARY This program is being conducted for the purpose of applying...can be achieved in superalloy powder materials for optimization of mechanical properties above I., Tm. MAR M200 alloy powder, processed and reacted in

  1. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, M.A., E-mail: mgonzalez@comimsa.com.mx [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Martinez, D.I., E-mail: dorairma@yahoo.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Perez, A., E-mail: betinperez@hotmail.com [Facultad de Ingenieria Mecanica y Electrica (FIME-UANL), Av. Universidad s/n. Ciudad Universitaria, C.P.66451 San Nicolas de los Garza, N.L. (Mexico); Guajardo, H., E-mail: hguajardo@frisa.com [FRISA Aerospace, S.A. de C.V., Valentin G. Rivero No. 200, Col. Los Trevino, C.P. 66150, Santa Caterina N.L. (Mexico); Garza, A., E-mail: agarza@comimsa.com [Corporacion Mexicana de Investigacion en Materiales S.A. de C.V. (COMIMSA), Ciencia y Tecnologia No.790, Saltillo 400, C.P. 25295 Saltillo Coah. (Mexico)

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  2. N-benzoylated 1,4,8,11-tetraazacyclotetradecane and their copper(II) and nickel(II) complexes: Spectral, magnetic, electrochemical, crystal structure, catalytic and antimicrobial studies

    Science.gov (United States)

    Nirmala, G.; Rahiman, A. Kalilur; Sreedaran, S.; Jegadeesh, R.; Raaman, N.; Narayanan, V.

    2010-09-01

    A series of N-benzoylated cyclam ligands incorporating three different benzoyl groups 1,4,8,11-tetra-(benzoyl)-1,4,8,11-tetraazacyclotetradecane (L 1), 1,4,8,11-tetra-(2-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 2) and 1,4,8,11-tetra-(4-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 3) and their nickel(II) and copper(II) complexes are described. Crystal structure of L 1 is also reported. The ligands and complexes were characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. N-benzoylation causes red shift in the λmax values of the complexes. The cyclic voltammogram of the complexes of ligand L 1 show one-electron, quasi-reversible reduction wave in the region -1.00 to -1.04 V, whereas that of L 2 and L 3 show two quasi-reversible reduction peaks. Nickel complexes show one-electron quasi-reversible oxidation wave at a positive potential in the range +1.05 to +1.15 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment values μeff 1.70-1.73 BM which is close to the spin-only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. All the ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.

  3. The development of a 2D ultrasonic array system for the in situ inspection of single crystal turbine blades

    Science.gov (United States)

    Lane, C. J. L.; Dunhill, A. K.; Drinkwater, B. W.; Wilcox, P. D.

    2012-05-01

    Modern jet-engine turbine blades are cast from single crystals of nickel-based superalloys because of the excellent mechanical properties that these materials exhibit at high temperatures. However, the anisotropic behavior of single crystals causes difficulties when using ultrasound to inspect these components for defects that could potentially initiate in-service. This paper describes the development of a 2D ultrasonic array system for the in situ inspection of these components. The problems associated with the inspection of anisotropic single crystal materials such as the directional dependence of the ultrasonic velocity, beam directivities in anisotropic media and the variation in the crystallographic orientation, are all addressed in this paper. In addition, constraints regarding access to the inspection location within the engine are discussed. Finally, the defect detection sensitivity and sizing capability of the developed system is evaluated.

  4. Oxidation and emittance of superalloys in heat shield applications

    Science.gov (United States)

    Wiedemann, K. E.; Clark, R. K.; Unnam, J.

    1986-01-01

    Recently developed superalloys that form alumina coatings have a high potential for heat shield applications for advanced aerospace vehicles at temperatures above 1095C. Both INCOLOY alloy MA 956 (of the Inco Alloys International, Inc.), an iron-base oxide-dispersion-strengthened alloy, and CABOT alloy No. 214 (of the Cabot Corporation), an alumina-forming nickel-chromium alloy, have good oxidation resistance and good elevated temperature strength. The oxidation resistance of both alloys has been attributed to the formation of a thin alumina layer (alpha-Al2O3) at the surface. Emittance and oxidation data were obtained for simulated Space Shuttle reentry conditions using a hypersonic arc-heated wind tunnel. The surface oxides and substrate alloys were characterized using X-ray diffraction and scanning and transmission electron microscopy with an energy-dispersive X-ray analysis unit. The mass loss and emittance characteristics of the two alloys are discussed.

  5. The characteristics of serrated flow in superalloy IN738LC

    Energy Technology Data Exchange (ETDEWEB)

    Sharghi-Moshtaghin, Reza [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)], E-mail: rxs270@case.edu; Asgari, Sirous [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran (Iran, Islamic Republic of)

    2008-07-15

    Serrated flow was investigated in superalloy IN738LC, a nickel-base {gamma}' age-hardened alloy. In this material serrated flow appeared between 350 and 450 deg. C and strain rate of (8.77 x 10{sup -5} to 8.77 x 10{sup -3}) s{sup -1}. Activation energy for this process was calculated to be 0.69-0.86 eV which is in good agreement with the values reported for similar alloys. Results show that the diffusion rate of substitutional solute atoms at this temperature range is too low to cause this effect. This suggests that the interaction of solute atoms and moving dislocation is responsible for the observed serrated flow in this alloy.

  6. Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

    Institute of Scientific and Technical Information of China (English)

    CHEN Jiping; DING Zhiping

    2007-01-01

    The coupling effect of normal stress and shear stress on orthotropic materials happens when applied loading deflects from the directions of the principal axes of the material coordinate system.By taking account of the coupling effects,formulas of equivalent stress and strain for cubic single crystal materials are cited.Using the equivalent strain and equivalent stress for such material and a variable k,which is introduced to express the effect of asymmetrical cyclic loading on fatigue life,a low cycle fatigue (LCF) life prediction model for such material in multiaxial stress starts is proposed.On the basis of the yield criterion and constitutive model of cubic single crystal materials,a subroutine to calculate the thermo elastic-plastic stress-strain of the material on an ANSYS platform was developed.The cyclic stress-strain of DD3 notched specimens under asymmetrical loading at 680℃ was analyzed.Low cycle fatigue test data of the single crystal nickel-based superalloy are used to fit the different parameters of the power law with multiple linear regression analysis.The equivalent stress and strain for a cubic single crystal material as failure parameters have the largest correlation coefficient.A power law exists between k and the failure cycle.The model was validated with LCF test data of CMSX-2 and DD3 single crystal nickel-based superalloys.All the test data fall into the factor of 2.5 for CMSX-2 hollow cylinder specimens and 2.0 scatter band for DD3 notched specimens,respectively.

  7. Synthesis and Crystal Structure of a New Ternary Complex of Nickel(Ⅱ) with L-Aspartic Acid and 1,10-Phenanthroline

    Institute of Scientific and Technical Information of China (English)

    马录芳; 梁福沛; 覃海错; 胡瑞祥; 张漫波

    2004-01-01

    A new ternary complex of nickel(Ⅱ) with L-aspartate (L-Asp) and 1, 10-phenanthroline(Phen), [Ni3(L-Asp)(Phen)5(H2O)3](ClO4)4.4.75H2O, has been synthesized in a mixed solvent of H2OC2H5OH at the pH value of 3. It crystallizes in triclinic, space group P-1 with a =11.861(2), b = 18.384(4), c = 19.746(3)(°A), α = 107.68(1), β = 105.94(1), γ= 103.41(2)°, V =3703.6(11) (°A)3, Mr = 1745.66, Z = 2, Dc =1.565 g/cm3, u = 0.989 mm-1, F(000) = 1791, R = 0.0643and wR = 0.1611. The complex contains two cations, binuclear [Ni2(L-Asp)(Phen)3(H2O)]2+ and mononu- clear [Ni(Phen)2(H2O)2]2+. All the nickel ions in the complex are six-coordinated with a distorted octahedral geometry, but the coordination environments for them are different. There exist hydrogen bonds and π-π stacking interactions in the complex.

  8. Nickel(II) complexes of N2S2 donor set ligand and halide/pseudohalides: Synthesis, crystal structure, DNA and bovine/human serum albumin interaction

    Indian Academy of Sciences (India)

    Animesh Patra; Biplab Mondal; Buddhadeb Sen; Ennio Zangrando; Pabitra Chattopadhyay

    2015-11-01

    A series of neutral hexacoordinated nickel(II) complexes of formula [NiII (L)X2] (where L = 3,4-bis(2-pyridylmethylthio)toluene with tetradentate N2S2 donor set and X = chloride (1), azide (2), cyanate (3) and isothiocyanate anion (4)) have been synthesized and isolated in pure form. The complexes were characterized by physicochemical and spectroscopic methods along with detailed structural characterization of 1,2 and 3 by single crystal X-ray diffraction analyses. The structural study showed that the nickel(II) ion has a distorted octahedral geometry being chelated by the tetradentate N2S2 ligand and bound to cis- located choride or pseudohalide anions. In dimethylformamide solution the complexes showed quasi-reversible NiII/NiIII redox couples in cyclic voltammograms with E1/2 values of +0.723, +0.749, +0.768 and +0.868 V for 1, 2, 3 and 4, respectively. The study of interaction of the complexes with calf thymus DNA, bovine serum albumin (BSA) and human serum albumin (HSA) using spectroscopic and physicochemical tools clearly indicates that the complexes interact with DNA via groove binding mode.

  9. Microplasticity and dislocation mobility in copper-nickel single crystals evaluated from strain-amplitude-dependent internal friction. [CuNi

    Energy Technology Data Exchange (ETDEWEB)

    Nishino, Y.; Okada, Y.; Asano, S. (Dept. of Materials Science and Engineering, Nagoya Inst. of Tech. (Japan))

    1992-02-16

    Internal friction in copper-0.4 to 7.6 at% nickel single crystals is measured as a function of strain amplitude at various temperatures. Analysis of the data on the amplitude-dependent internal friction yields the relation of effective stress and microplastic strain of the order of 10{sup -9}. The stress-strain responses thus obtained exhibit that the microplastic flow stress increases more rapidly on alloying than the macroscopic yield stress. The mean dislocation velocity is also evaluated from the internal-friction data, which corresponds well to the etch-pit data. It is shown that the dislocation motion is impeded by friction due to dispersed solute atoms. (orig.).

  10. Effect of size discrepancy of. gamma. - and. gamma. '-phases crystal lattice parameters on heat resisting dispersion hardening nickel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Petrushin, N.V.; Ignatova, I.A.; Logunov, A.V.; Samojlov, A.I.; Razumovskij, I.M.

    Effect of Cr, Co, Nb and W alloying elements on crystal lattice parameters of ..gamma.. ahd ..gamma..' phases in Ni-Cr-Co-W-Al-Ti- Nb-Hf alloys and on their dimensional misfit at 293 and 1173 K is studied. Alloying at which alloys have the parameter of ..gamma..-solid solution lattice less than that of ..gamma..'-phase results in low heat-resistant properties and in considerable difference of coefficients of thermal expansion of the phases. Definite positive misfit of ..gamma..- and ..gamma..'-phase lattices and a low temperature gradient are the conditions of high heat resistance of complex-alloyed nickel alloys. Possible mechanisms of lattice misfit effect on strength and coalescence kinetics of the second phase in heterogeneous alloys at high temperatures are discussed.

  11. Nickel(II) complexes containing ONS donor ligands: Synthesis, characterization, crystal structure and catalytic application towards C-C cross-coupling reactions

    Indian Academy of Sciences (India)

    Panneerselvam Anitha; Rajendran Manikandan; Paranthaman Vijayan; Govindan Prakash; Periasamy Viswanathamurthi; Ray Jay Butcher

    2015-04-01

    Nickel(II) complexes containing thiosemicarbazone ligands [Ni(L)2] (1-3) (L = 9,10-phenanthrenequinonethiosemicarbazone (HL1), 9,10-phenanthrenequinone-N-methylthio semicarbazone (HL2) and 9, 10-phenanthrenequinone-N-phenylthiosemicarbazone (HL3)) have been synthesized and characterized by elemental analysis and spectroscopic (IR, UV-Vis, 1H, 13C-NMR and ESI mass) methods. The molecular structures of complexes 1 and 2 were identified by means of single-crystal X-ray diffraction analysis. The analysis revealed that the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate ONS fashion. The catalytic activity of complexes towards some C–C coupling reactions (viz., Kumada-Corriu, Suzuki-Miyaura and Sonogashira) has been examined. The complexes behave as efficient catalysts in the Kumada-Corriu and Sonogashira coupling reactions rather than Suzuki-Miyaura coupling.

  12. Resource-saving technologies of making advanced cast and deformable superalloys with allowance for processing all types of wastes

    Science.gov (United States)

    Kablov, E. N.; Sidorov, V. V.; Kablov, D. E.; Min, P. G.; Rigin, V. E.

    2016-12-01

    The results of thermodynamic analysis of the vacuum-melt-ceramic system and experimental investigations of using up to 100% wastes during vacuum-induction melting are presented. An important role of rare-earth and alkaline-earth metals and heat treatment is shown for effective refining of a melt from impurities and gases. As a result, a resource-saving technology of making advanced cast and deformable nickel superalloys is developed with allowance for processing all types of wastes, including off-grade wastes. The developed technology of refining wastes under vacuum makes it possible to manufacture the alloys that fully meet the requirements of alloy specifications from 100% wastes. This technology is now used for the mass production of nickel superalloys in a research complex at FGUP VIAM.

  13. The effect of microstructure on the fatigue behavior of Ni base superalloys

    Science.gov (United States)

    Antolovich, S. D.; Jayaraman, N.

    1983-01-01

    Nickel-base superalloys are used in jet engine components such as disks, turbine blades, and vanes. Improvements in the fatigue behavior will allow the life to be extended or the payloads to be increased. The first part of the present investigation deals primarily with the effects of microstructural variations on the fatigue crack propagation (FCP) behavior of nickel-base alloys, while the second part is concerned with low-cycle fatigue (LCF) behavior of Ni base systems. Waspaloy at low temperature is considered, taking into account material heat treatment and test procedures, a composite plot of Waspaloy FCP data, Paris law fatigue crack propagation constants, monotonic tensile data, and overload FCP test results for Waspaloy. It is found that the FCP and overload behavior of nickel-base alloys may be markedly improved by heat treating. Attention is given to effects of cyclic deformation on microstructure and substructure, environmental damage, and an environmental/deformation model of high temperature LCF.

  14. Retention of Compressive Residual Stresses Introduced by Shot Peening in a Powder Metal Disk Superalloy

    Science.gov (United States)

    Gabb, Timothy P.; Danetti, Andrew; Draper, Susan L.; Locci, Ivan E.; Telesman, Jack

    2016-01-01

    The fatigue lives of disk superalloys can be increased by shot peening their surfaces, to induce compressive residual stresses near the surface that impede cracking there. As disk application temperatures increase for improved efficiency, the persistence of these beneficial stresses could be impaired, especially with continued fatigue cycling. The objective of this work was to study the retention of residual stresses introduced by shot peening, when subjected to fatigue and high temperatures. Fatigue specimens of powder metallurgy processed nickel-base disk superalloy ME3 were prepared with consistent processing and heat treatment. They were then shot peened using varied conditions. Strain-controlled fatigue cycles were run at room temperature and 704 C, to allow re-assessment of residual stresses.

  15. Corrosion-resistant nickel-base alloys for gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J.W.; Hulsizer, W.R.

    1976-08-01

    Laboratory corrosion screening procedures used during the past ten years in developing nickel-base superalloys for gas turbine applications are described. Hot salt corrosion tests have included crucible and salt shower exposures. Reproducible techniques were established and alloy composition effects defined, leading to development of M313, IN-587, a IN-792. Correlations have been made with corrosion results in burner rigs, and engine experience confirming anticipated behavior is now becoming available. During this work a number of limitations of these accelerated laboratory tests were uncovered; these are discussed. Finally, brief descriptions of the states of development of alloy MA 755E (an oxide dispersion-strengthened superalloy) and IN-939 (a cast 23 percent chromium superalloy) are outlined as examples of advanced corrosion resistant, high strength materials of the future.

  16. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Vesel, Alenka; Drenik, Aleksander; Elersic, Kristina; Mozetic, Miran; Kovac, Janez [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Gyergyek, Tomaz [University of Ljubljana, Faculty of Electrical Engineering, Trzaska 25, SI-1000 Ljubljana (Slovenia); Stockel, Jan; Varju, Jozef; Panek, Radomir [Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Ze Slovankou 3, Praha 8 (Czech Republic); Balat-Pichelin, Marianne, E-mail: marianne.balat@promes.cnrs.fr [PROMES-CNRS Laboratory, 7 rue du four solaire, 66120 Font Romeu Odeillo (France)

    2014-06-01

    Initial stages of Inconel 625 superalloy (Ni{sub 60}Cr{sub 30}Mo{sub 10}Ni{sub 4}Nb{sub 1}) oxidation upon short treatment with gaseous plasma at different temperatures up to about 1600 K were studied. Samples were treated for different periods up to a minute by oxygen or hydrogen plasma created with a microwave discharge in the standing-wave mode at a pressure of 40 Pa and a power 500 W. Simultaneous heating of the samples was realized by focusing concentrated solar radiation from a 5 kW solar furnace directly onto the samples. The morphological changes upon treatment were monitored using scanning electron microscopy, compositional depth profiling was performed using Auger electron spectroscopy, while structural changes were determined by X-ray diffraction. The treatment in oxygen plasma caused formation of metal oxide clusters of three dimensional crystallites initially rich in nickel oxide with the increasing chromium oxide content as the temperature was increasing. At about 1100 K iron and niobium oxides prevailed on the surface causing a drop of the material emissivity at 5 μm. Simultaneously the NiCr{sub 2}O{sub 4} compound started growing at the interface between the oxide film and bulk alloy and the compound persisted up to temperatures close to the Inconel melting point. Intensive migration of minority alloying elements such as Fe and Ti was observed at 1600 K forming mixed surface oxides of sub-micrometer dimensions. The treatment in hydrogen plasma with small admixture of water vapor did not cause much modification unless the temperature was close to the melting point. At such conditions aluminum segregated on the surface and formed well-defined Al{sub 2}O{sub 3} crystals.

  17. 镍基高温合金上双层搪瓷-陶瓷复合涂层1000℃氧化机理%Oxidation Behavior of Bilayered Ceramic Particle-reinforced Enamel Composite Coating on Nickel-based Superalloy K38G at 1000 ℃

    Institute of Scientific and Technical Information of China (English)

    沈明礼; 朱圣龙; 王福会

    2012-01-01

    A bilayered enamel-ceramic composite coating, consisted of an inner layer of enamel-50 mass% corundum and an outer layer of enamel-50 mass% quartz, was prepared on nickel-based superalloy K38G by spray-sintering technique. The coating is dense with glaze surface and has good adhesion to the substrate. Its oxidation behavior at 1000 ℃ for 120 h was studied by means of thermogravimetry, SEM, EDS and XRD. Cristobalite, a high-temperature polymorph of quartz, and zircon and albite precipitates were detected in the as-prepared enamel-ceramic composite coating. In addition, Ni, Co and Cr were present in the inner layer of enamel-corundum. The mass gain of the coated alloy after 120 h oxidation was about 0.2 mg/cm2, quite lower than those of NiCrA1Y coatings. Most of the quartz particles in the coating transformed into cristobalite after oxidation tests. Besides, orthoelase was detected too. Ni-enrichment was observed in the outermost region of the outer layer, while Cr-enrichment was found in the inner layer close to the inner/outer interface. And Ni-, Cr-, Al-enrichment were found in the inner layer near the substrate either of the as-prepared samples or of the samples after oxidation tests.%在镍基高温合金K38G基体上制备了双层搪瓷-陶瓷复合涂层,其中面层为搪瓷-50mass%石英,底层为搪瓷-50mass%刚玉层.涂层结合力良好,表面均匀致密,有釉面光泽.1000℃、120h氧化结果表明,涂层试样的氧化增重仅为0.2mg/cm^2左右,比文献中报道的NiCrAlY涂层的氧化速率低数倍(Ni-22Cr-10Al-1Y(mass%)1000℃100h氧化增重已达1.2mg/cm^2).刚制备出的搪瓷-陶瓷复合涂层中的部分石英颗粒已转变为方石英相,并析出少量的锆英石相和钠长石相.氧化后的涂层中大部分石英颗粒转变成方石英,并析出少量的钾长石相.氧化后的涂层试样中Ni,Cr富集分别出现在涂层的外层靠近空气区域和内层靠近外层

  18. Development of advanced P/M Ni-base superalloys for turbine disks

    Directory of Open Access Journals (Sweden)

    Garibov Genrikh S.

    2014-01-01

    Full Text Available In the process of evolution of powder metallurgy in Russia the task permanently formulated was the following: to improve strength properties of P/M superalloys without application of additional complex HIPed blanks deformation operation. On the other hand development of a turbine disk material structure to ensure an improvement in aircraft engine performance requires the use of special HIP and heat treatment conditions. To ensure maximum strength properties of disk materials it is necessary to form a structure which would have optimum size of solid solution grains, γ′-phases and carbides. Along with that heating of the material up to a temperature determined by solvus of an alloy ensures a stable and reproducible level of mechanical properties of the disks. The above-said can be illustrated by successful mastering of new complex-alloyed VVP-class superalloys with the use of powder size − 100 μm. Application of special HIP and heat treatment conditions for these superalloys to obtain the desired grain size and the strengthening γ′-phase precipitates allowed a noticeable improvement in ultimate tensile strength and yield strength up to ≥1600 MPa and ≥1200 MPa respectively. 100 hrs rupture strength at 650 ∘C and 750 ∘C was improved up to 1140 MPa and 750 MPa respectively. P/M VVP nickel-base superalloys offer higher characteristics in comparison with many superalloys designed for the same purposes. HIPed disc compacts manufactured from PREP-powder have a homogeneous micro- and macrostructure, a stable level of mechanical properties.

  19. New knowledge about 'white spots' in superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Jackman, L.A. (Teledyne Allvac, Monroe, N.C. (United States)); Maurer, G.E. (Special Metals Corp., New Hartford, N.Y. (United States)); Widge, S. (Carpenter Technology Corp., Reading, PA (United States))

    1993-05-01

    In April 1991, the first in a series of workshops was held to discuss ways in which the gas turbine industry could better understand defects in nickel-base superalloys. The group's primary objective was to better define, and expand knowledge about, segregation in superalloys such as Alloy 718 and Waspaloy,with emphasis on light-etching areas referred to as solute-lean defects or 'white spots'. This 'White Spots Committee' formed four subcommittees to focus efforts on classification, inspection, mechanisms, and mechanical properties. Completion of the tasks that these subcommittees have undertaken should greatly improve the gas turbine industry's understanding of the physical and mechanical nature of white spots. The primary purpose of this article is to formalize the characterization and classification of white spots in high-strength superalloys so that the metallurgical community can begin to use a common vocabulary when referring to them. An overview of formation mechanisms is presented along with a brief description of detection methods. Also discussed are preliminary test results, which should help shed light on the effects of solute-lean microstructures on tensile and fatigue properties. Although white spots are not limited to any single superalloy or class of superalloy, Alloy 718 is emphasized because it is so widely used, and because its relatively large solidus-liquidus temperature interval ([approximately]75 C, 135 F) and high niobium content ([approximately]5.3% Nb) make it prone to segregation. Three distinct types of white spots have been identified and named by the committee: discrete, dendritic, and solidification white spots.

  20. CCDC 1505386: Experimental Crystal Structure Determination : catena-[bis(mu-pyrazine)-(mu-fluoro)-(mu-oxido)-tetrafluoro-nickel-niobium carbon dioxide

    KAUST Repository

    Bhatt, Prashant

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  1. CCDC 1404097: Experimental Crystal Structure Determination : catena-((mu2-Hexafluorosilicato)-bis(mu2-pyrazine)-nickel dihydrate)

    KAUST Repository

    Shekhah, Osama

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  2. CCDC 1477136: Experimental Crystal Structure Determination : catena-[bis(mu-pyrazine)-(mu-oxido)-(mu-fluoro)-tetrafluoro-nickel-niobium dihydrate

    KAUST Repository

    Cadiau, Amandine

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  3. Lattice parameter variations during aging in nickel-base superalloys

    Science.gov (United States)

    Nathal, M. V.; Mackay, R. A.; Garlick, R. G.

    1988-01-01

    The importance of the state of coherency on measurements of gamma/gamma-prime lattice mismatch has been experimentally demonstrated during aging at 1000 C of specimens of an alloy with composition Ni-(8.6)Cr-(5.3)Al-(10.1)Co-(11.7)W-(1.2)Ti-(0.7)Mo (wt pct). Lattice parameter measurements are given as a function of aging time, and the corresponding sample microstructures are presented. The results show that changes of the two phases during aging did not influence the lattice parameter measurements, indicating that aging specimens to produce a semicoherent gamma/gamma-prime structure provides a good approximation of the true, unconstrained lattice mismatch.

  4. Performance of nickel base superalloy components in gas turbines

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter

    2006-01-01

    The topic of this thesis is the microstructural behaviour of hot section components in the industrial gas turbine......The topic of this thesis is the microstructural behaviour of hot section components in the industrial gas turbine...

  5. Thermal conductivity of nickel superalloy MAR-M247

    OpenAIRE

    P. Jonšta; Koštial, P.; Jonšta, Z.; Vlčková, I.; T. Kulová

    2016-01-01

    The paper presents the narrow connection between γ’ phase dissolving and values of thermal conductivity. In annealing process the free space among γ’ particles (blocks) changes in certain cycle from fine to rough and back to fine. This is accompanied by decrease and subsequent increase of thermal conductivity as well as the sample density. The results of thermal conductivity coarse are supported by image analysis. Web of Science 55 3 422 420

  6. A Review on Inertia and Linear Friction Welding of Ni-Based Superalloys

    Science.gov (United States)

    Chamanfar, Ahmad; Jahazi, Mohammad; Cormier, Jonathan

    2015-04-01

    Inertia and linear friction welding are being increasingly used for near-net-shape manufacturing of high-value materials in aerospace and power generation gas turbines because of providing a better quality joint and offering many advantages over conventional fusion welding and mechanical joining techniques. In this paper, the published works up-to-date on inertia and linear friction welding of Ni-based superalloys are reviewed with the objective to make clarifications on discrepancies and uncertainties reported in literature regarding issues related to these two friction welding processes as well as microstructure, texture, and mechanical properties of the Ni-based superalloy weldments. Initially, the chemical composition and microstructure of Ni-based superalloys that contribute to the quality of the joint are reviewed briefly. Then, problems related to fusion welding of these alloys are addressed with due consideration of inertia and linear friction welding as alternative techniques. The fundamentals of inertia and linear friction welding processes are analyzed next with emphasis on the bonding mechanisms and evolution of temperature and strain rate across the weld interface. Microstructural features, texture development, residual stresses, and mechanical properties of similar and dissimilar polycrystalline and single crystal Ni-based superalloy weldments are discussed next. Then, application of inertia and linear friction welding for joining Ni-based superalloys and related advantages over fusion welding, mechanical joining, and machining are explained briefly. Finally, present scientific and technological challenges facing inertia and linear friction welding of Ni-based superalloys including those related to modeling of these processes are addressed.

  7. A Study on the Effects on Low Cycle Fatigue Life of a High Pressure Turbine Nozzle due to the Perturbation of Crystal Orientation of Grain of DS Materials

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Jae Sung; Kang, Young Seok; Rhee, Dong Ho [Korea Aerospace Research Institute, Daejeon (Korea, Republic of)

    2016-07-15

    High pressure components of a gas turbine engine are generally made of nickel-base superalloys, using precision casting process due to complicated geometries with intricate channels and cooling holes. Turbine components manufactured from directionally solidified and single crystal materials have columnar grains; however, it is found that the crystals do not grow in its preferred direction, although the orientation can be controlled. This anisotropy can lead to the variations of elastic and Hill's parameters in constitutive equations, and they alter stress distributions and the low cycle fatigue life. We aims to evaluate the effects of perturbed crystal orientations on the structural integrity of a directionally solidified nozzle using low cycle fatigue life. We also attempt to show the necessity for the control of allowed manufacturing errors and stochastic analysis. Our approaches included conjugate heat transfer and structural analysis, along with low cycle fatigue life assessment.

  8. Preparation,Characterization and Crystal Structure Determination of a Nickel Complex[Ni(ftsc)2NO3]NO3(Hftsc=Furan-2-carbaldehyde Thiosemicarbazone)

    Institute of Scientific and Technical Information of China (English)

    BAI Yan; PAN Xiao-Jing; DANG Dong-Bin; JIN Ya-Nan; WANG Jing-Ping

    2008-01-01

    A new Ni(Ⅱ)complex,[Ni(ftsc)2NO3]NO3(Hftsc=furan-2-carbaldehyde thiosemicarbazone),has been synthesized and characterized by IR,UV spectra and single-crystal X-ray diffraction analysis.It crystallizes in a monoclinic system,space group P21/n,with a=10.5203(13),b=9.2094(11),c=20.829(3)(A),β=91.518(2)°,V=2017.3(5)(A)3,Z=4,F(000)=1064,Dc=1.716 g/cm3,and wR=0.0800.The complex contains a six-coordinated nickel(Ⅱ)center which is bound to two imine nitrogen atoms and two thiolato sulfur atoms of two ligands as well as two oxygen atoms from a nitrate anion to assume a distorted octahedral coordination geometry.In addition,intermolecular N-H…O and C-H…O hydrogen bonds between adjacent molecules link the molecules together to form a three-dimensional structure.

  9. 单晶高温合金DD6再结晶晶界析出相特征及其形成机制%CHARACTERISTIC AND FORMATION MECHANISM OF PRECIPITATES AT RECRYSTALLIZATION GRAIN BOUNDARIES OF SINGLE CRYSTAL SUPERALLOY DD6

    Institute of Scientific and Technical Information of China (English)

    熊继春; 李嘉荣; 赵金乾; 刘世忠; 董建新

    2009-01-01

    Single crystal superalloys have extremely good elevated temperature capability in advanced gas turbine aero engines due to no highly stressed grain boundaries in them. With the removal of grain boundary strengthening elements such as C, B and Zr, the occurrence of recrystallization may be detrimental to their performance. Therefore, recrystallization becomes critical in industrial manufacture of single crystal superalloy blades. In the present study, specimens of single crystal superalloy DD6 were grit blasted, solution treated and aged at vacuum atmosphere, and then the precipitates at recrystallization grain boundaries were investigated by SEM, TEM, EPMA and Thermo-Calc. The results show that a few of M_6C carbides precipitate at recrystallization grain boundaries, and their size is about 0.5 μm. These M_6C carbides are rich in W, Re and Mo, but poor in Al, Ta, Ni, the contents of Cr, Nb, Co in them are almost the same as the nominal composition of DD6 alloy. The carbon accumulation at recrystallization boundaries and combination with μ phase forming elements such as W and Mo restrain the μ phase forming. M_(23)C_6 phase hardly forms in DD6 alloy due to its high W and low Cr content.%对单晶高温合金DD6进行表面吹砂处理,然后进行固溶与时效真空热处理,采用SEM,TEM,EPMA和Thermo-Calc的方法研究了单晶合金DD6再结晶晶界析出相的特征及其形成机制.结果表明,经过吹砂处理的DD6合金在固溶与时效热处理过程中发生再结晶.再结晶晶界出现析出相,分析表明析出相为M6C碳化物,该碳化物呈粒状析出,尺寸约为0.5 μm,数量极少,富含W,Re和Mo,且Cr,Nb和Co的含量与合金名义成分差别不大,而Al,Ta和Ni含量较低.由于再结晶晶界上C元素的聚集效应,C原子在晶界上达到一定浓度后即与一定数量的W,Mo等μ相形成元素发生相变反应,抑制了合金析出μ相的倾向.又因为DD6合金W含量较高,而Cr含量较低,抑制了M_(23)C_6

  10. Investigation of delamination mechanisms during a laser drilling on a cobalt-base superalloy

    OpenAIRE

    Girardot, Jérémie; Schneider, Matthieu; Berthe, Laurent; FAVIER, Véronique

    2013-01-01

    International audience; Temperatures in the high pressure chamber of aircraft engines are continuously increasing to improve the engine efficiency. As a result, constitutive materials such as cobalt and nickel-base superalloys need to be thermally protected. The first protection is a ceramic thermal barrier coating (TBC) cast on all the hot gas-exposed structure. The second protection is provided by a cool air layer realized by the use of a thousand of drills on the parts where a cool air is flo...

  11. Nickel Farm

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Most plants find nickel to be pretty nasty stuff, and they won’t grow in soils rich in the metal.Streptanthus polygaloides. on the other hand.loves nickel.This member of the mustard family grows only in high-nickel soil in the shadow of the Sierra Nevada,in central California.Streptanthus is a rare type of plant known as a "hyperaccumulator." All plants take up nutrients

  12. Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

    Institute of Scientific and Technical Information of China (English)

    Shihong ZHANG; Zhongtang WANG; Bing QIAO; Yi XU; Tingfeng XU

    2005-01-01

    The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080~1120℃, and the temperature range recommended for the tools is 350~500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed.With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150~200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.

  13. Freckle Defect Formation near the Casting Interfaces of Directionally Solidified Superalloys

    Directory of Open Access Journals (Sweden)

    Jianping Hong

    2016-11-01

    Full Text Available Freckle defects usually appear on the surface of castings and industrial ingots during the directional solidification process and most of them are located near the interface between the shell mold and superalloys. Ceramic cores create more interfaces in the directionally solidified (DS and single crystal (SX hollow turbine blades. In order to investigate the location of freckle occurrence in superalloys, superalloy CM247 LC was directionally solidified in an industrial-sized Bridgman furnace. Instead of ceramic cores, Alumina tubes were used inside of the casting specimens. It was found that freckles occur not only on the casting external surfaces, but also appear near the internal interfaces between the ceramic core and superalloys. Meanwhile, the size, initial position, and area of freckle were investigated in various diameters of the specimens. The initial position of the freckle chain reduces when the diameter of the rods increase. Freckle area follows a linear relationship in various diameters and the average freckle fraction is 1.1% of cross sectional area of casting specimens. The flow of liquid metal near the interfaces was stronger than that in the interdendritic region in the mushy zone, and explained why freckle tends to occur on the outer or inner surfaces of castings. This new phenomenon suggests that freckles are more likely to occur on the outer or inner surfaces of the hollow turbine blades.

  14. A study of microstructural characteristics of Ni-based superalloys at high temperatures

    Science.gov (United States)

    Lal, Ravindra B.; Aggarwal, M. D.

    1990-01-01

    The microstructural characteristics of the Ni-based superalloy MAR-M245(Hf) which is used in manufacturing the components of the Space Shuttle main engine are studied. These superalloys need optimum heat treatment to get the best results. To find out the optimum heat treatment, the techniques of differential thermal analysis (DTA) and the optical photomicrographs were utilized. In the first phase, the existing experimental equipment like cutting, grinding/polishing machines and metallurgical microscope were set up to cut/polish and take the photomicrographs. In the beginning of the project a Perkin Elmer differential thermal analyzer DTA1700 along with a temperature programmed and the needed computer interface was procured and made operational. In the second year a Leitz Metallux-3 hot state research microscope was also procured and installed for in-situ observation of the superalloy samples. The hot stage when tested for the first time alloyed the thermocouple with the Tantalum heating element and has now been installed. Samples of MAR-M246(Hf), MAR-M247, Waspaloy, Udimet-41, CMSX-3, and CMSX-3 (Polycrystalline and single crystals) were studied using a differential thermal analyzer and the results are reported. Photomicrographs of the Ni-based superalloy MAR-M246 (Hf) were recorded before and after heat treatment at certain temperatures. More heat treatments need to be done before a final inference can be reached.

  15. Phase transformation and segregation to lattice defects in Ni-base superalloys.

    Science.gov (United States)

    Blavette, Didier; Cadel, Emmanuel; Pareige, Cristelle; Deconihout, Bernard; Caron, Pierre

    2007-12-01

    Nanostructural features of nickel-base superalloys as revealed by atom probe field ion microscopy (APFIM) and atom probe tomography (APT) are reviewed. The more salient information provided by these techniques is discussed through an almost exhaustive analysis of literature over the last 30 years. Atom probe techniques are shown to be able to measure the composition of tiny gamma' precipitates, a few nanometers in size, and to reveal chemical order within these precipitates. Phase separation kinetics in model NiCrAl alloys was investigated with both 3DAP and Monte-Carlo simulation. Results are shown to be in good agreement. Plane by plane analysis of {001} planes of Ni(3)Al-type gamma' phase makes it possible to estimate the degree of order as well as the preferential sites of various addition elements (Ti, Cr, Co, W, Ta, Re, Ru, etc.) included in superalloys. Clustering effects of Re in the gamma solid solution were also exhibited. Due to its ultrahigh depth resolution, the microchemistry of interfaces and grain boundaries can be characterized on an atomic scale. Grain boundaries in Astroloy or N18 superalloys were found to be enriched in B, Mo, and Cr and Al depleted.

  16. Crystal structure of bis[S-hexyl 3-(4-methylbenzylidenedithiocarbazato-κ2N3,S]nickel(II

    Directory of Open Access Journals (Sweden)

    M. B. H. Howlader

    2015-02-01

    Full Text Available In the title complex, [Ni(C15H21N2S22], the NiII atom exhibits a square-planar coordination geometry and is located on an inversion centre leading to a trans configuration of the N,S-chelating ligands. In the crystal, the complex molecules stack at a distance of 4.6738 (3 Å along the a axis, which exclude any significant interactions between the aromatic rings.

  17. Synthesis of Large-Sized Single-Crystal Hexagonal Boron Nitride Domains on Nickel Foils by Ion Beam Sputtering Deposition.

    Science.gov (United States)

    Wang, Haolin; Zhang, Xingwang; Liu, Heng; Yin, Zhigang; Meng, Junhua; Xia, Jing; Meng, Xiang-Min; Wu, Jinliang; You, Jingbi

    2015-12-22

    Large-sized single-crystal h-BN domains with a lateral size up to 100 μm are synthesized on Ni foils by ion-beam sputtering deposition. The nucleation density of h-BN is dramatically decreased by reducing the concentrations of both active sites and species on the Ni surface through a brief in situ pretreatment of the substrate and optimization of the growth parameters, enabling the growth of large-sized domains.

  18. Effect of Re Addition and Withdrawal Rate on the Solidification Behavior of Directionally Solidified Superalloy AM3

    Institute of Scientific and Technical Information of China (English)

    F.Long; Y.S.Yoo; S.M.Seo; T.Jin; Z.Q.Hu; C.Y.Jo

    2011-01-01

    The influence of Re addition and withdrawal rate on the solidification behavior of the first generation single crystal superalloy AM3 was investigated by directional solidification and quenching experiments. The primary dendrite arm spacing and eutectic volume fraction were measured from directionally solidified superalloy AM3 with different Re contents. It is found that the primary dendrite arm spacing is determined by the withdrawal rate, and Re does not influence on the value. The eutectic fraction increases with increasing Re addition. Partition coefficients of alloying elements were investigated with energy-dispersive X-ray spectrometry (EDS) analysis. The data was submitted to a statistical treatment to establish the solidification path, and the partition coefficients were measured by fitting the curve with a modified Scheil formula. It is shown that the addition of Re results in bigger microsegregation of alloying elements in directionally solidified AM3 superalloy.

  19. Influence of Processing Parameters on Grain Size Evolution of a Forged Superalloy

    Science.gov (United States)

    Reyes, L. A.; Páramo, P.; Salas Zamarripa, A.; de la Garza, M.; Guerrero-Mata, M. P.

    2016-01-01

    The microstructure evolution of nickel-based superalloys has a great influence on the mechanical behavior during service conditions. Microstructure modification and the effect of process variables such as forging temperature, die-speed, and tool heating were evaluated after hot die forging of a heat-resistant nickel-based alloy. Forging sequences in a temperature range from 1253 to 1323 K were considered through experimental trials. An Avrami model was applied using finite element data to evaluate the average grain size and recrystallization at different evolution zones. It was observed that sequential forging at final temperatures below 1273 K provided greater grain refinement through time-dependent recrystallization phenomena. This investigation was aim to explore the influence of forging parameters on grain size evolution in order to design a fully homogenous and refined microstructure after hot die forging.

  20. Computational and Experimental Design of Fe-Based Superalloys for Elevated-Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter K. [Univ. of Tennessee, Knoxville, TN (United States); Fine, Morris E. [Northwestern Univ., Evanston, IL (United States); Ghosh, Gautam [Northwestern Univ., Evanston, IL (United States); Asta, Mark D. [Univ. of California, Berkeley, CA (United States); Liu, Chain T. [Auburn Univ., AL (United States); Sun, Zhiqian [Univ. of Tennessee, Knoxville, TN (United States); Huang, Shenyan [Univ. of Tennessee, Knoxville, TN (United States); Teng, Zhenke [Univ. of Tennessee, Knoxville, TN (United States); Wang, Gongyao [Univ. of Tennessee, Knoxville, TN (United States)

    2012-04-13

    Analogous to nickel-based superalloys, Fe-based superalloys, which are strengthened by coherent B2- type precipitates are proposed for elevated-temperature applications. During the period of this project, a series of ferritic superalloys have been designed and fabricated by methods of vacuum-arc melting and vacuum-induction melting. Nano-scale precipitates were characterized by atom-probe tomography, ultrasmall- angle X-ray scattering, and transmission-electron microscopy. A duplex distribution of precipitates was found. It seems that ferritic superalloys are susceptible to brittle fracture. Systematic endeavors have been devoted to understanding and resolving the problem. Factors, such as hot rolling, precipitate volume fractions, alloy compositions, precipitate sizes and inter-particle spacings, and hyperfine cooling precipitates, have been investigated. In order to understand the underlying relationship between the microstructure and creep behavior of ferric alloys at elevated temperatures, in-situ neutron studies have been carried out. Based on the current result, it seems that the major role of β' with a 16%-volume fraction in strengthening ferritic alloys is not load sharing but interactions with dislocations. The oxidation behavior of one ferritic alloy, FBB8 (Fe-6.5Al-10Ni-10Cr-3.4Mo-0.25Zr-0.005B, weight percent), was studied in dry air. It is found that it possesses superior oxidation resistance at 1,023 and 1,123 K, compared with other creep-resistant ferritic steels [T91 (modified 9Cr-1Mo, weight percent) and P92 (9Cr-1.8W-0.5Mo, weight percent)]. At the same time, the calculation of the interfacial energies between the -iron and B2-type intermetallics (CoAl, FeAl, and NiAl) has been conducted.

  1. Solution heat-treatment of Nb-modified MAR-M247 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Soares Azevedo e Silva, Paulo Ricardo, E-mail: paulori@alunos.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Baldan, Renato, E-mail: renato@ppgem.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Nunes, Carlos Angelo, E-mail: cnunes@demar.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); Carvalho Coelho, Gilberto, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Escola de Engenharia de Lorena (EEL), Departamento de Engenharia de Materiais DEMAR, Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12600-970, Lorena, Sao Paulo (Brazil); UniFoa, Centro Universitario de Volta Redonda, Nucleo de Pesquisa, Campus Tres Pocos, Avenida Paulo Erlei Alves Abrantes, 1325, Bairro Tres Pocos, 27240-560, Volta Redonda, Rio de Janeiro (Brazil); and others

    2013-01-15

    MAR-M247 superalloy has excellent mechanical properties and good oxidation resistance at elevated temperatures. Niobium is an element known as {gamma} Prime phase hardener in nickel-based superalloys, besides promoting homogeneous distribution of MC carbides. This work is inserted in a project that aims to evaluate the total replacement of tantalum by niobium atoms in MAR-M247 superalloy (10.2 Co, 10.2 W, 8.5Cr, 5.6 Al, 1.6 Nb, 1.4 Hf, 1.1 Ti, 0.7 Mo, 0.15 C, 0.06 Zr, 0.015 B, Ni balance-wt.%). Based on microstructural characterizations (SEM and FEG-SEM, both with EDS) of the as-cast material and heat-treated materials as well as utilizing Thermocalc simulations and experiments of differential thermal analysis (DTA), heat-treatment at 1260 Degree-Sign C for 8 h was chosen as an ideal condition for the solution of Nb-modified MAR-M247 superalloy. The hardness of as-cast and ideally solution treated materials was 390 {+-} 14 HV and 415 {+-} 6 HV, respectively. - Highlights: Black-Right-Pointing-Pointer DTA and microstructure of MAR-M247(Nb) showed a good agreement with Thermocalc. Black-Right-Pointing-Pointer An ideal condition for solution heat-treatment of MAR-M247(Nb) is 1260 Degree-Sign C for 8 h. Black-Right-Pointing-Pointer It was an observed evidence of incipient melting in samples heat-treated at 1280 Degree-Sign C.

  2. Synthesis, Crystal Structure and Theoretical Calculation of a Novel Nickel(II) Complex with Dibromotyrosine and 1,10-Phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Guimei; Zhang, Xia; Fan, Yuhua; Bi, Caifeng; Yan, Xingchen; Zhang, Zhongyu; Zhang, Nan [Ocean Univ. of China, Qingdao (China)

    2013-10-15

    A new complex [Ni(phen)(C{sub 9}H{sub 8}Br{sub 2}NO{sub 3}){sub 2}·2CH{sub 3}OH·2H{sub 2}O] [phen: 1,10-phenanthroline C{sub 9}H{sub 8}Br{sub 2}NO{sub 3}: 3,5-dibromo-L-tyrosine] was synthesized and characterized by IR, elemental analysis and single crystal X-ray diffraction. X-ray crystallography shows that Ni(II) ion is six-coordinated. The Ni(II) ion coordinates with four nitrogen atoms and two oxygen atoms from three ligands, forming a mononuclear Ni(II) complex. The crystal crystallizes in the Orthorhombic system, space group P2{sub 1}2{sub 1}2 with a = 12.9546 A, b = 14.9822 A, c = 9.9705 A, V = 1935.2 A, Z = 1, F(000) = 1008, S = 0.969, ρ{sub calcd} = 1.742 g·cm{sup -3}, μ = 4.688 mm{sup -1}, R{sub 1} = 0.0529 and wR{sub 2} = 0.0738 for 3424 observed reflections (I > 2σ(I)). Theoretical study of the title complex was carried out by density functional theory (DFT) method and the B3LYP method employing the 6-3l+G{sup *} basis set. The energy gap between HOMO and LUMO indicates that this complex is prone to interact with DNA. CCDC: 908041.

  3. Syntheses, crystal structures, spectral and DFT studies of copper(II) and nickel(II) complexes with N‧-(pyridine-2-ylmethylene)acetohydrazide

    Science.gov (United States)

    Patel, Ram N.; Singh, Yogendra Pratap; Singh, Yogendra; Butcher, Ray J.; Zeller, Matthias; Singh, R. K. Bhubon; U-wang, Oinam

    2017-05-01

    Three new metal(II) complexes (copper(II)/nickel(II)) with N'-(pyridine-2-ylmethylene) acetohydrazide [Cu(HL)2]·(ClO4)21, [Ni(HL)2]·NO3·ClO4·0.5H2O 2 and [Cu(μ-CH3COO)(L)]2·4H2O 3 have been synthesized form N‧-(pyridine-2-ylmethylene) acetohydrazide (HL/L). The synthesized complexes were characterized by means of elemental analysis, spectroscopic, magnetic susceptibility and cyclic voltammetric measurements. Single crystal X-ray analysis of complexes has revealed the presence of a distorted octahedral geometry around mononuclear copper(II) and nickel(II) complex (1 and 2) and distorted square pyramidal geometry around copper(II) centers of complex 3. In the solid state Schiff base remains in its keto-tautomeric form. On complexation with Cu(II)/Ni(II) ions in natural or slightly acidic medium it coordinates through ketonic oxygen (keto form, HL) whereas in basic medium it acts as monoprotic (enol form, L) ligand. Variable-temperature magnetic susceptibility data of the compound 3 indicates the presence of weak antiferromagnetic interaction with J = -12.3 cm-1. The cyclic voltammograms of homobinuclear complex 3 in DMSO gave two irreversible waves which correspond to the Cu(II,II)/Cu(II,I) and Cu(II,I)/Cu(I,I) redox processes. On the other hand, the mononuclear complex 1 exhibited M(II)/M(I) quasireversible wave E1/2 = 0.06 V vs Ag/AgCl. X-band electron paramagnetic resonance (epr) data of copper(II) mononuclear and binuclear complexes 1 and 3 have been collected to investigate magnetic properties of the complexes in detail. The electronic structures, spectral properties of the ligands and the complexes have been explained by DFT and TD-DFT calculations. In addition, biological activity ranking of present complexes 1-3 are investigated theoretically. Complexes catalyzed the dismutation of superoxide (O2▪-) at biological pH in alkaline nitroblue tetrazolium chloride assay and IC50 values were evaluated.

  4. RESEARCH ON REFRACTORY SUPERALLOYS IN THE HTM 21 PROJECT

    Institute of Scientific and Technical Information of China (English)

    Y.F.Gu; Y.Yamabe-Mitarai; C.Huang; H.Harada

    2005-01-01

    It was proposed that a new class of alloys based on platinum group metals (PGMs) were called refractory superalloys.These refractory superalloys have an fcc and LI2 coherent two-phase structure (similar to that of Ni-based superalloys), high melting temperatures and good potential as structural materials used at temperatures up to 1800℃.Our recent results on the microstructure evolution, deformation and fracture behavior of some of these refracotry superalloys, especial Ir- and Rh-base refractory superalloys were reported.

  5. Creep and residual mechanical properties of cast superalloys and oxide dispersion strengthened alloys

    Science.gov (United States)

    Whittenberger, J. D.

    1981-01-01

    Tensile, stress-rupture, creep, and residual tensile properties after creep testing were determined for two typical cast superalloys and four advanced oxide dispersion strengthened (ODS) alloys. The superalloys examined included the nickel-base alloy B-1900 and the cobalt-base alloy MAR-M509. The nickel-base ODS MA-757 (Ni-16CR-4Al-0.6Y2O3 and the iron-base ODS alloy MA-956 (Fe-20Cr-5Al-0.8Y2O3) were extensively studied, while limited testing was conducted on the ODS nickel-base alloys STCA (Ni-16Cr-4.5Al-2Y2O3) with a without Ta and YD-NiCrAl (Ni-16Cr-5Al-2Y2O3). Elevated temperature testing was conducted from 114 to 1477 K except for STCA and YD-NiCrAl alloys, which were only tested at 1366 K. The residual tensile properties of B-1900 and MAR-M509 are not reduced by prior creep testing (strains at least up to 1 percent), while the room temperature tensile properties of ODS nickel-base alloys can be reduced by small amounts of prior creep strain (less than 0.5 percent). The iron-base ODS alloy MA-956 does not appear to be susceptible to creep degradation at least up to strains of about 0.25 percent. However, MA-956 exhibits unusual creep behavior which apparently involves crack nucleation and growth.

  6. Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy

    Science.gov (United States)

    Kuppan, Saravanan; Xu, Yahong; Liu, Yijin; Chen, Guoying

    2017-02-01

    Understanding the reaction pathway and kinetics of solid-state phase transformation is critical in designing advanced electrode materials with better performance and stability. Despite the first-order phase transition with a large lattice mismatch between the involved phases, spinel LiMn1.5Ni0.5O4 is capable of fast rate even at large particle size, presenting an enigma yet to be understood. The present study uses advanced two-dimensional and three-dimensional nano-tomography on a series of well-formed LixMn1.5Ni0.5O4 (0<=x<=1) crystals to visualize the mesoscale phase distribution, as a function of Li content at the sub-particle level. Inhomogeneity along with the coexistence of Li-rich and Li-poor phases are broadly observed on partially delithiated crystals, providing direct evidence for a concurrent nucleation and growth process instead of a shrinking-core or a particle-by-particle process. Superior kinetics of (100) facets at the vertices of truncated octahedral particles promote preferential delithiation, whereas the observation of strain-induced cracking suggests mechanical degradation in the material.

  7. Fatigue Resistance of the Grain Size Transition Zone in a Dual Microstructure Superalloy Disk

    Science.gov (United States)

    Gabb, T. P.; Kantzos, P. T.; Telesman, J.; Gayda, J.; Sudbrack, C. K.; Palsa, B. S.

    2010-01-01

    Mechanical property requirements vary with location in nickel-based superalloy disks. To maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored microstructures. In this study, a specialized heat treatment method was applied to produce varying grain microstructures from the bore to the rim portions of a powder metallurgy processed nickel-based superalloy disk. The bore of the contoured disk consisted of fine grains to maximize strength and fatigue resistance at lower temperatures. The rim microstructure of the disk consisted of coarse grains for maximum resistance to creep and dwell crack growth at high temperatures up to 704 C. However, the fatigue resistance of the grain size transition zone was unclear, and needed to be evaluated. This zone was located as a band in the disk web between the bore and rim. Specimens were extracted parallel and transverse to the transition zone, and multiple fatigue tests were performed at 427 and 704 C. Mean fatigue lives were lower at 427 C than for 704 C. Specimen failures often initiated at relatively large grains, which failed on crystallographic facets. Grain size distributions were characterized in the specimens, and related to the grains initiating failures as well as location within the transition zone. Fatigue life decreased with increasing maximum grain size. Correspondingly, mean fatigue resistance of the transition zone was slightly higher than that of the rim, but lower than that of the bore. The scatter in limited tests of replicates was comparable for all transition zone locations examined.

  8. Electrochemical isolation of intermetallic and carbide phases from nickel-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shul' ga, A.V.; Nikishanov, V.V.; Ofitserov, A.V.

    1988-01-01

    Parameters of carbide phases were examined to find the optimum conditions for isolating intermetallic and carbide phases from complex nickel-base alloys. Conditions for an electrochemical isolation of the phases are chosen on the basis of polarization curves for the matrix and phases to be isolated. Electrochemical studies were performed with a potentiostat and data from x-ray analyses of the phases are tabulated. Two electrolytes were developed, the first for isolating carbide phases from nickel matrix and from nickel-base superalloys and the second electrolyte isolates intermetallic phases.

  9. Nickel nanofibers synthesized by the electrospinning method

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yi [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China); Zhang, Xuebin, E-mail: zzhhxxbb@126.com [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China); Zhu, Yajun; Li, Bin; Wang, Yang; Zhang, Jingcheng; Feng, Yi [School of Materials Science and Engineering, Hefei University of Technology, Anhui 230000 (China)

    2013-07-15

    Highlights: ► The nickel nanofibers have been obtained by electrospinning method. ► The nickel nanofibers had rough surface which was consisted of mass nanoparticles. ► The average diameter of nickel nanofibers is about 135 nm and high degree of crystallization. ► The Hc, Ms, and Mr were estimated to be 185 Oe, 51.9 and 16.9 emu/g respectively. - Abstract: In this paper, nickel nanofibers were prepared by electrospinning polyvinyl alcohol/nickel nitrate precursor solution followed by high temperature calcination in air and deoxidation in hydrogen atmosphere. The thermal stability of the as-electrospun PVA/Ni(NO{sub 3}){sub 2} composite nanofibers were characterized by TG–DSC. The morphologies and structures of the as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electronmicroscope (FE-SEM) and field-emission transmission electron microscopy (FE-TEM). The hysteresis loops (M–H loops) were measured by Physical Property Measurement System (PPMS). The results indicate that: the PVA and the nickel nitrate were almost completely decomposed at 460 °C and the products were pure nickel nanofibers with face-centered cubic (fcc) structure. Furthermore, the as-prepared nickel nanofibers had a continuous structure with rough surface and high degree of crystallization. The average diameter of nickel nanofibers was about 135 nm. The nanofibers showed a stronger coercivity of 185 Oe than value of bulk nickel.

  10. Thresholds of time dependent intergranular crack growth in a nickel disc alloy Alloy 720Li

    OpenAIRE

    Li Hangyue; Fisk Joe; Lim Lik-Beng; Williams Steve; Bowen Paul

    2014-01-01

    At high temperatures in air, introducing a dwell period at the peak stress of fatigue cycles promotes time dependent intergranular crack growth which can increase crack growth rates by upto a few orders of magnitude from the rates of transgranular fatigue crack growth in superalloys. It is expected that time dependent intergranular crack growth in nickel-based superalloys may not occur below a critical mechanical driving force, ΔKth−IG, analogous to a fatigue threshold (ΔKth) and a critical t...

  11. Laser engineered net shaping of Co-based superalloys

    Institute of Scientific and Technical Information of China (English)

    XUE Chun-fang; DAI Yao; TIAN Xin-li

    2006-01-01

    Laser engineered net shaping(LENS) process was investigated using Co-based superalloy powder with a high power continuous wave CO2 laser. Thin wall part with smooth surface was obtained by LENS of layer-by-layer deposition of the powder materials. This thin wall sample was tested for metallographic examinations, micro-hardness, X-ray diffraction and mechanical property test. Microstructural results show that the layers possess rapid solidification microstructural feature, fine dendritic crystal and M7C3-type carbides (essentially chromium-rich carbide) dispersed in the γ(Co,Cr) phase matrix. Dendrite spacing as well as the solidification mode can be controlled through control process parameters. In addition, this microstructural feature of the as-formed Co-base sample leads to an evident hardening and a superior tensile strength and toughness.

  12. Structure of ultradisperse nickel particles produced by the thermolysis of nickel formate-monoethanol amine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Khvorov, M.M.; Dudchenko, A.K.; Khimchenko, IU.I.

    1986-05-01

    Histograms of the size distribution of ultradisperse nickel particles produced by the thermolysis of amine complexes are plotted using dark-field and light-field electron microscopy data. It is found that the size distribution can be adequately approximated by logarithmically probabilistic functions. The ultradisperse nickel particles feature several types of structure, i.e., faceted stable single crystals coated by an organic film, small aggregates of such crystals, large stable globules, and hexahedral and trihedral crystals. 8 references.

  13. Crystal structure of hexa-aqua-nickel(II) bis-{5-bromo-7-[(2-hy-droxy-eth-yl)amino]-1-methyl-6-oxido-quinolin-1-ium-3-sulfonate} monohydrate.

    Science.gov (United States)

    Le Thi Hong, Hai; Nguyen Thi Ngoc, Vinh; Do Thi Van, Anh; Van Meervelt, Luc

    2016-09-01

    The asymmetric unit of the title compound, [Ni(H2O)6](C12H12BrN2O5S)2·H2O, contains a half hexa-aqua-nickel(II) complex cation with the Ni(II) ion lying on an inversion center, one 5-bromo-7-[(2-hy-droxy-eth-yl)amino]-1-methyl-6-oxido-quinolin-1-ium-3-sulfonate (QAO) anion and a half lattice water mol-ecule on a twofold rotation axis. In the crystal, QAO anions are stacked in a column along the c axis by π-π stacking inter-actions [centroid-centroid distances 3.5922 (10)-3.7223 (11) Å]. The columns are inter-linked by hexa-aqua-nickel(II) cations through O-H⋯O and N-H⋯O hydrogen bonds.

  14. Nickel allergy

    DEFF Research Database (Denmark)

    Fischer, L A; Johansen, J D; Menné, T

    2007-01-01

    BACKGROUND: The frequency of nickel allergy varies between different population groups. Exposure regulation has proven effective in decreasing the frequency. Experimental studies with other allergens have shown a significant relation between patch test reactivity and repeated open application test.......78 microg nickel cm(-2) in the patch test. The threshold for the ROAT (in microg nickel cm(-2) per application) was significantly lower than the threshold for the patch test, while the dose-response for the accumulated ROAT dose at 1 week, 2 weeks and 3 weeks was very similar to the patch test dose......-response; indeed, there was no statistically significant difference. CONCLUSIONS: For elicitation of nickel allergy the elicitation threshold for the patch test is higher than the elicitation threshold (per application) for the ROAT, but is approximately the same as the accumulated elicitation threshold...

  15. Crystal structure of bis{2-[(E-(4-fluorobenzyliminomethyl]phenolato-κ2N,O}nickel(II

    Directory of Open Access Journals (Sweden)

    Amalina Mohd Tajuddin

    2014-10-01

    Full Text Available The asymmetric unit of the title complex, [Ni(C14H11FNO2], contains one-half of the molecule with the NiII cation lying on an inversion centre coordinated by a bidentate Schiff base anion. The cationic NiII center is in a distorted square-planar coordination environment chelated by the imine N and phenolate O donor atoms of the two Schiff base ligands. The N and O donor atoms of the two ligands are mutually trans with Ni—N and Ni—O bond lengths of 1.9242 (10 and 1.8336 (9 Å, respectively. The fluorophenyl ring is almost orthogonal to the coordination plane and makes a dihedral angle of 82.98 (7° with the phenolate ring. In the crystal, molecules are linked into screw chains by weak C—H...F hydrogen bonds. Additional C—H...π contacts arrange the molecules into sheets parallel to the ac plane.

  16. Crystal structure of bis{2-[(E-(4-methoxylbenzyliminomethyl]phenolato-κ2N,O1}nickel(II

    Directory of Open Access Journals (Sweden)

    Hadariah Bahron

    2014-08-01

    Full Text Available The asymmetric unit of the title compound, [Ni(C15H14NO22], comprises an NiII cation, lying on an inversion centre, and a Schiff base anion that acts as a bidentate ligand. The NiII cation is in a square-planar coordination environment binding to the imine N and phenolate O atoms of the two Schiff base ligands. The N- and O-donor atoms of the two ligands are mutually trans, with Ni—N and Ni—O bond lengths of 1.9191 (11 and 1.8407 (9 Å, respectively. The plane of the methoxybenzene ring makes a dihedral angle of 84.92 (6° with that of the phenolate ring. In the crystal, molecules are linked into screw chains by weak C—H...O hydrogen bonds. Additional C—H...O hydrogen bonds, together with C—H...π contacts, arrange the molecules into sheets parallel to the ac plane.

  17. Crystal structure of bis(3-bromopyridine-κNbis(O-ethyl dithiocarbonato-κ2S,S′nickel(II

    Directory of Open Access Journals (Sweden)

    Rajni Kant

    2015-01-01

    Full Text Available In the title molecular complex, [Ni(C3H5OS22(C5H4BrN2], the Ni2+ cation is located on a centre of inversion and has a distorted octahedral N2S4 environment defined by two chelating xanthate ligands and two monodentate pyridine ligands. The C—S bond lengths of the thiocarboxylate group are indicative of a delocalized bond and the O—Csp2 bond is considerably shorter than the O—Csp3 bond, consistent with a significant contribution of one resonance form of the xanthate anion that features a formal C=O+ unit and a negative charge on each of the S atoms. The packing of the molecules is stabilized by C—H...S and C—H...π interactions. In addition, π–π interactions between the pyridine rings [centroid-to-centroid distance = 3.797 (3 Å] are also present. In the crystal structure, molecules are arranged in rows along [100], forming layers parallel to (010 and (001.

  18. Oxidation Resistance: One Barrier to Moving Beyond Ni-Base Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A [ORNL; Distefano, James R [ORNL; Wright, Ian G [ORNL

    2006-01-01

    The implementation of new high-temperature materials is often hampered by their lack of oxidation or environmental resistance. This failing is one of the strongest barriers to moving beyond Ni-base superalloys for many commercial applications. In practice, usable high-temperature alloys have at least reasonable oxidation resistance, but the current generation of single-crystal Ni-base superalloys has sufficient oxidation resistance that optimized versions can be used without a metallic bond coating and only an oxygen-transparent ceramic coating for thermal protection. The material development process often centers around mechanical properties, while oxidation resistance, along with other realities, is given minor attention. For many applications, the assumption that an oxidation-resistant coating can be used to protect a substrate is seriously flawed, as coatings often do not provide sufficient reliability for critical components. Examples of oxidation problems are given for currently used materials and materials classes with critical oxidation resistance problems.

  19. Development of superalloys for 1700 C ultra-efficient gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Hiroshi [National Institute for Materials Science, Tsukuba, Ibaraki (Japan). High Temperature Materials Center

    2010-07-01

    Mitigation of global warming is one of the most outstanding issues for the humankind. The Japanese government announced that it will reduce its greenhouse gas emissions by 25% from the 1990 level by 2020 as a medium-term goal. One of the promising approaches to achieving this is to improve the efficiency of thermal power plants emitting one-third of total CO{sub 2} gas in Japan. The key to improving the thermal efficiency is high temperature materials with excellent temperature capabilities allowing higher inlet gas temperatures. In this context, new single crystal superalloys for turbine blades and vanes, new coatings and turbine disk superalloys have been successfully developed for various gas turbine applications, typically 1700 C ultra-efficient gas turbines for next generation combine cycle power plants. (orig.)

  20. Structural Performance of Inconel 625 Superalloy Brazed Joints

    Science.gov (United States)

    Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

    2016-12-01

    The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S-N curve, providing a design curve for any joint configuration in fatigue solicitation.

  1. Chemical driving force for rafting in superalloys

    CSIR Research Space (South Africa)

    Nabarro, FRN

    1997-08-15

    Full Text Available The author provides a brief overview of the chemical driving forces for rafting in superalloys. Until recently, all theories of the driving force for rafting have considered the compositions of the two phases to be fixed, although accepting...

  2. 水合羟基高氯酸镍(Ⅱ)的晶体结构%Crystal Structure of the [nickel(Ⅱ)-(μ3-hydroxide)-(μ3-perchlorate)-aqua]n Complex

    Institute of Scientific and Technical Information of China (English)

    吴倩; 宋玉梅; 袁荣鑫; 熊仁根

    2004-01-01

    Green single crystal of the title compound was accidentally obtained by the reaction of N,N′-bis(pyridylcarbonyl)-4,4′-diaminodiphenyl ether (L) with nickel perchlorate. In the structure of [Ni(μ3-OH)(μ3-ClO4)(H2O)]n, the local coordinating geometry around Ni center displays a distorted octahedron in which one coordination site of each metal atom was occupied by a water molecule. Each perchlorate anion and hydroxyl group acts as a tridentate bridging spacer to bind three Ni atoms, thus resulting in the formation of two-dimensional layered network.

  3. Determination of inconsistency of crystal lattice parameters of. gamma. - and. gamma. '-phases of nickel heat resisting alloys by Fourier-analysis of x-ray diffraction reflex profiles

    Energy Technology Data Exchange (ETDEWEB)

    Samojlov, A.I.; Ignatova, I.A.; Krivko, A.I.; Kozlova, V.S.; Dodonova, L.P.

    1983-01-01

    A method is outlined that enables with the use of Fourier-analysis of summary unresolved X-ray diffraction profile of the matrix ..gamma.. and intermetallic ..gamma..' phases of nickel heat resisting alloys of the Ni-Cr-Co-Al-Ti-Nb-W-Mo-V -Hf system, to calculate the location of reflexes of each phase, that is, to determine the periods of their crystal lattices in the alloy (in monolith) directly without electrolytic separation of ..gamma..'-phase. The limits of the method applicability were determined.

  4. Nickel metallomics: general themes guiding nickel homeostasis.

    Science.gov (United States)

    Sydor, Andrew M; Zamble, Deborah B

    2013-01-01

    The nickel metallome describes the distribution and speciation of nickel within the cells of organisms that utilize this element. This distribution is a consequence of nickel homeostasis, which includes import, storage, and export of nickel, incorporation into metalloenzymes, and the modulation of these and associated cellular systems through nickel-regulated transcription. In this chapter, we review the current knowledge of the most common nickel proteins in prokaryotic organisms with a focus on their coordination environments. Several underlying themes emerge upon review of these nickel systems, which illustrate the common principles applied by nature to shape the nickel metallome of the cell.

  5. A New Polycrystalline Co-Ni Superalloy

    Science.gov (United States)

    Knop, M.; Mulvey, P.; Ismail, F.; Radecka, A.; Rahman, K. M.; Lindley, T. C.; Shollock, B. A.; Hardy, M. C.; Moody, M. P.; Martin, T. L.; Bagot, P. A. J.; Dye, D.

    2014-12-01

    In 2006, a new-ordered L12 phase, Co3(Al,W), was discovered that can form coherently in a face-centered cubic (fcc) A1 Co matrix. Since then, a community has developed that is attempting to take these alloys forward into practical applications in gas turbines. A new candidate polycrystalline Co-Ni γ/ γ' superalloy, V208C, is presented that has the nominal composition 36Co-35Ni-15Cr-10Al-3W-1Ta (at.%). The alloy was produced by conventional powder metallurgy superalloy methods. After forging, a γ' fraction of ~56% and a secondary γ' size of 88 nm were obtained, with a grain size of 2.5 μm. The solvus temperature was 1000°C. The density was found to be 8.52 g cm-3, which is similar to existing Ni alloys with this level of γ'. The alloy showed the flow stress anomaly and a yield strength of 920 MPa at room temperature and 820 MPa at 800°C, similar to that of Mar-M247. These values are significantly higher than those found for either conventional solution and carbide-strengthened Co alloys or the γ/ γ' Co superalloys presented in the literature thus far. The oxidation resistance, with a mass gain of 0.08 mg cm-2 in 100 h at 800°C, is also comparable with that of existing high-temperature Ni superalloys. These results suggest that Co-based and Co-Ni superalloys may hold some promise for the future in gas turbine applications.

  6. Constitutive Model for an FCC Single-Crystal Material

    Institute of Scientific and Technical Information of China (English)

    DING Zhi-ping; LIU Yi-lun; YIN Ze-yong; YANG Zhi-guo; CHENG Xiao-ming

    2006-01-01

    Talking into account the effects that the components of tension stresses couple with components of torsion stresses when off-axis loads are applied to orthotropic materials.Hill's yield criterion for plastically orthotropic solids is modified by adding an invariant that is composed of the product item of quadratic components of the deviatoric siress tensor,and a new yield criteflon is put forward in terms of the characteristics of the face-centered cubic(FCC) single-crystal material.The correlation of prediction and experiments is very good.and the new criterion is used to predict the yield stresses of an intemal single-crystal,Nickel-based superalloy,DD3,which is more accurate than that Of Hill's at 760°C.Equivalent stress and strain that adapt to the new criterion are defined.Thinking of the yield function as a plastic potential function from the associated flow rule.the elastic-plastic constitutive model for the FCC single-crystal material is constructed,and the corresponding elastic-plastic matrix iseduced.The new yield criterion and its equivalent stress and strain will be reduced to Von Mises' yield criterion and corresponding equivalent stress and strain for isotropic materials.

  7. ADVANCED NICKEL-BASED AND NICKEL-IRON-BASED SUPERALLOYS FOR CIVIL ENGINEERING APPLICATIONS

    Institute of Scientific and Technical Information of China (English)

    U. Brill

    2005-01-01

    The use of high-temperature materials is especially important in power station construction,heating systems engineering, furnace industry, chemical and petrochemical industry, waste incineration plants, coal gasification plants and for flying gas turbines in civil and military aircrafts and helicopters. Particularly in recent years, the development of new processes and the drive to improve the economics of existing processes have increased the requirements significantly so that it is necessary to change from well-proven materials to new alloys. Hitherto, heat resistant ferritic steels sufficed in conventional power station constructions for temperatures up to 550℃ newly developed ferritic/martensitic steels provide sufficient strength up to about 600-620℃. In new processes, e.g. fiuidized-bed combustion of coal, process temperatures up to 900℃ occur. However, this is not the upper limit, since in combustion engines, e.g. gas turbines. Material temperatures up to 1100℃ are reached locally. Similar development trends can also be identified in the petrochemical industry and in the heat treatment and furnace engineering. The advance to ever higher material temperatures now not only has the consequence of having to use materials with enhanced high-strength properties, considerable attention now also has to be given to their chemical stability in corrosive media. Therefore not only examples of the use of high-temperature alloys for practical applications will be given but also be contributed to some general rules for material selection with regard to their high-temperature strength and corrosion resistance.

  8. Characterisation of zeolitic materials with a HEU-type structure modified by transition metal elements: definition of acid sites in nickel-loaded crystals in the light of experimental and quantum-chemical results.

    Science.gov (United States)

    Godelitsas, A; Charistos, D; Tsipis, A; Tsipis, C; Filippidis, A; Triantafyllidis, C; Manos, G; Siapkas, D

    2001-09-03

    Nickel-loaded HEU-type zeolite crystals have been obtained by well-known synthetic procedures and characterised by X-ray fluorescence (XRF), scanning-electron microscopy/ energy-dispersive spectroscopy (SEM-EDS), FT-IR, diffuse reflectance UV/ Vis spectroscopy (DR(UV/Vis)S) and X-ray photoelectron spectroscopy (XPS) measurements as non-homoionic and non-stoichiometric substances containing exchangeable hydrated Ni2+ ions in the micropores and nickel hydroxide phases supported on the surface. Thermogravimetric analysis/differential gravimetry (TGA/DTG) and differential thermal analysis (DTA) demonstrated that full dehydration below approximately 400 degrees C follows a clearly endothermic process, whereas at higher temperatures the zeolite is amorphised and finally partially recrystallised to Ni(Al,Si) oxides, detected by powder X-ray powder diffraction (XRD). The solid acidity of NiHEU, initially determined by temperature-programmed desorption (TPD) of ammonia to be 8.93 mgg(-1) NH3, is attributed to the weak acid sites (fundamentally Lewis sites) resolved at approximately 183 degrees C, and to the strong acid sites (essentially Brønsted sites) resolved at approximately 461 degrees C in the TPD pattern. A more sophisticated study based on in situ/ex situ FT-IR with in situ/ex situ 27Al MAS NMR and pyridine (Py) as a probe molecule, revealed that the Lewis acid sites can be attributed primarily to Ni2+ ions, whereas the Brønsted ones can probably be associated with the surface-supported nickel hydroxide phases. The spectroscopic measurements in conjunction with powder XRD and 29Si MAS NMR data strongly suggest that distorted Al tetrahedra are formed during the dehydration process and Py chemisorption/complexation (NiHEU-Py), whereas the crystal structure is remarkably well preserved in the rehydrated material (NiHEU-Py/R). The structural, electronic, energetic and spectroscopic properties of all possible nickel(II) aqua and dihydroxy complexes absorbed in the

  9. Isothermal Oxidation Comparison of Three Ni-Based Superalloys

    Science.gov (United States)

    Mallikarjuna, H. T.; Richards, N. L.; Caley, W. F.

    2017-05-01

    Ni-based superalloys are used for high-temperature components of gas turbines in both industrial and aerospace applications due to their ability to maintain dimensional stability under conditions of high stress and strain. The oxidation resistance of these alloys often dictates their service lifetime. This study focuses on the isothermal oxidation behavior of three Ni-based superalloys, namely, polycrystalline cast IN738LC, single-crystal N5, and a ternary Ni-Fe-Cr (TAS) powder metallurgy alloy. The isothermal oxidation tests were conducted at 900 °C in the static air up to 1000 h, and the specific aspects studied were the oxidation behavior of these chromia-forming and alumina-forming alloys that are used extensively in industry. In particular, the behavior of oxide scale growth and subsurface changes were analyzed in detail using various techniques such as SEM, EDS, and AFM. From the isothermal oxidation kinetics, the oxidation rate constant, k p, was calculated for each alloy and found to be; k p = 2.79 × 10-6 mg2 cm-4 s-1 for IN738LC, k p = 1.42 × 10-7 mg2 cm-4 s-1 for N5 and k p = 1.62 × 10-7 mg2 cm-4 s-1 for TAS. Based on a microstructural analysis, IN738LC exhibited a continuous dense outer scale of Cr2O3 and discontinuous inner scale of Al2O3, whereas N5 and TAS showed a dense outer scale of Al2O3 alone. The results suggested that the N5 and PM-TAS alloys are more oxidation resistant than the IN738LC under these conditions.

  10. Towards low-friction and wear-resistant plasma sintering dies via plasma surface co-alloying CM247 nickel alloy with V/Ag and N

    Directory of Open Access Journals (Sweden)

    Zhang Zhenxue

    2015-01-01

    Full Text Available Nickel based superalloys have good oxidation and creep resistance and hence they can function under high mechanical stress and high temperatures. However, their undesirable tribological behaviour is the major technical barrier to the challenging high-temperature, lubricant-free plasma sintering tool application. In this study, nickel based CM247 superalloy surfaces were co-alloyed using innovative active screen plasma technology with both interstitial element (e.g. N and substitutional alloying elements (e.g. V and Ag to provide a synergy effect to enhance its tribological properties. The tribological behaviour of the plasma co-alloyed CM247 superalloy surfaces were fully evaluated using reciprocal and pin-on-disc tribometers at temperatures from room temperature to 600 ∘C. The experimental results demonstrate that the co-alloyed surface with N, Ag and V can effectively lower the friction coefficient, which is expected to help demoulding during lubricant-free plasma sintering.

  11. Effect of Inclusion on Mechanical Properties of Powder Metallurgical Superalloy%夹杂物对粉末冶金高温合金力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    李晓; 张麦仓; 张丽娜; 谢锡善

    2001-01-01

    综述了非金属夹杂物对粉末冶金镍基高温合金力学性能影响的研究现状,特别着重夹杂物尺寸、位置、形态、数量等对粉末冶金镍基高温合金低周疲劳寿命(LCF)的影响。文中提出粉末冶金高温合金存在的问题及今后的研究方向。%The present research status of the effect of non metal inclusion on powder metallurgical nickel base superalloy has been reviewed comprehensively, emphasis on the influence of inclusion size, location, morphology and quality on low-cycle fatigue (LCF) life of the superalloy. The existing points and the research direction in future for powder metallurgical superalloy are presented in this paper.

  12. Development of Wrought Superalloy in China

    Directory of Open Access Journals (Sweden)

    DU Jinhui

    2016-06-01

    Full Text Available Wrought superalloy development in China was reviewed in recent ten years. The achievement of basic research and development of industrial manufacture technologies were systematically described from the aspects of new alloys, new technologies of hot deformation. New alloys include: new disc materials 718Plus, GH4720Li and GH4065 alloy, combustion chamber alloy GH3230, and GH4706 alloy for gas turbine engines. New technologies include: ERS-CDS new technology of easy segregation materials, multi upsetting-drawing for improving the microstructure uniformity of bars, slow cooling and multi-cycle thermomechanical treatment for increasing hot plasticity of hard-to-work alloys. Finally, the further development of wrought superalloys was prospected.

  13. Thermal fatigue behavior of K465 superalloy

    Institute of Scientific and Technical Information of China (English)

    YANG Jinxia; ZHENG Qi; SUN Xiaofeng; GUAN Hengrong; HU Zhuangqi

    2006-01-01

    The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy (SEM) and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast (named as K465) and solution heat treatment (named as SK465) conditions.In K465 alloy, most thermal fatigue cracks nucleate at (Nb,W,Ti)C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode,and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.

  14. Hot Corrosion of Nickel-Base Alloys in Biomass-Derived Fuel Simulated Atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Leyens, C.; Pint, B.A.; Wright, I.G.

    1999-02-28

    Biomass fuels are considered to be a promising renewable source of energy. However, impurities present in the fuel may cause corrosion problems with the materials used in the hot sections of gas turbines and only limited data are available so far. As part of the Advanced Turbine Systems Program initiated by the U.S. Department of Energy, the present study provides initial data on the hot corrosion resistance of different nickel-base alloys against sodium sulfate-induced corrosion as a baseline, and against salt compositions simulating biomass-derived fuel deposits. Single crystal nickel-superalloy Rene N5, a cast NiCrAlY alloy, a NiCoCrAlY alloy representing industrially used overlay compositions, and a model {beta}NiAl+Hf alloy were tested in 1h thermal cycles at 950 C with different salt coatings deposited onto the surfaces. Whereas the NiCoCrAlY alloy exhibited reasonable resistance against pure sodium sulfate deposits, the NiCrAiY alloy and Rene N5 were attacked severely. Although considered to be an ideal alumina former in air and oxygen at higher temperatures, {beta}NiAl+Hf also suffered from rapid corrosion attack at 950 C when coated with sodium sulfate. The higher level of potassium present in biomass fuels compared with conventional fuels was addressed by testing a NiCoCrAlY alloy coated with salts of different K/Na atomic ratios. Starting at zero Na, the corrosion rate increased considerably when sodium was added to potassium sulfate. In an intermediate region the corrosion rate was initially insensitive to the K/Na ratio but accelerated when very Na-rich compositions were deposited. The key driver for corrosion of the NiCoCrAlY alloy was sodium sulfate rather than potassium sulfate, and no simple additive or synergistic effect of combining sodium and potassium was found.

  15. Effects of cobalt concentration on the relative resistance to octahedral and cube slip in nickle-base superalloys

    Science.gov (United States)

    Bobeck, Gene E.; Miner, R. V.

    1988-01-01

    Compression yielding tests were performed at 760 C on crystals of the Ni base superalloys Rene 150 and a modified MAR-M247, both having two different Co concentrations. For both alloy bases, increasing Co concentration was shown to decrease the critical resolved shear stress for octahedral slip, but to have little effect on that for cube slip. The results suggest that decreasing complex stacking fault energy in the gamma-prime with increasing Co could account for the observed effects.

  16. Orientation and Alloying Effects on Creep Strength in Ni-Based Superalloys

    Science.gov (United States)

    Smith, Timothy Michael, Jr.

    microtwin and stacking fault formations prominently occurred. High resolution EDX was performed in regions where stacking faults had terminated inside of a gamma' precipitate, capturing the process as it was transpiring when the creep test had ended. Again, the presence of elemental segregation was observed along superlattice stacking faults as well as multiple examples of a Co and Cr rich Cottrell atmosphere around the leading Shockley partials. The presence and interaction of newly discovered tertiary gamma particles with the formation of these faults is explored. These combined observations lead to the creation of a new microtwin formation model incorporating the diffusion processes now known to ensue during twin development. Finally, a new "phase-transformation strengthening" mechanism that resists high temperature creep deformation in Nickel-based superalloys, where specific alloying elements inhibit the deleterious deformation mode of microtwinning at temperatures above 700 °C is introduced. Ultra-high-resolution structure and composition analysis via scanning transmission electron microscopy, combined with density functional theory calculations, reveals that a superalloy with higher concentrations of the elements Titanium, Tantalum, and Niobium encourage a shear-induced solid-state transformation from the gamma' to phase along stacking faults in gamma' precipitates, which would normally be the precursors of deformation twins. This nanoscale phase creates a low energy structure that inhibits thickening of stacking faults into twins, leading to significant improvement in creep properties.

  17. High-temperature protective coatings on superalloys

    Institute of Scientific and Technical Information of China (English)

    刘培生; 梁开明; 周宏余

    2002-01-01

    Protective coatings are essential for superalloys to serve as blades of gas turb ines at high temperatures, and they primarily include aluminide coating, MCrAlY overlay coating, thermal barrier coating and microcrystalline coating. In this paper, all these high-temperature coatings are reviewed as well as their preparing techniques. Based on the most application and the main failure way, the importance is then presented for further deepgoing study on the high-temperature oxidation law of aluminide coatings.

  18. Development of Wrought Superalloy in China

    OpenAIRE

    DU Jinhui; ZHAO Guangpu; Deng, Qun; LÜ Xudong; ZHANG Beijiang

    2016-01-01

    Wrought superalloy development in China was reviewed in recent ten years. The achievement of basic research and development of industrial manufacture technologies were systematically described from the aspects of new alloys, new technologies of hot deformation. New alloys include: new disc materials 718Plus, GH4720Li and GH4065 alloy, combustion chamber alloy GH3230, and GH4706 alloy for gas turbine engines. New technologies include: ERS-CDS new technology of easy segregation materials, multi...

  19. Effects of helium impurities on superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Selle, J.E.

    1977-07-01

    A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented.

  20. CCDC 877428: Experimental Crystal Structure Determination : Deca-nickel oxonium octakis(benzene-1,3,5-tricarboxylate) (5,10,15,20-tetrakis(N-methyl-4-pyridinio)porphyrin)-nickel tetracosahydrate

    KAUST Repository

    Zhang, Zhenjie

    2012-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  1. Barrier Coatings for Refractory Metals and Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-02-23

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.

  2. Grain Boundary Engineering of a Low Stacking Fault Energy Ni-based Superalloy

    Science.gov (United States)

    McCarley, Joshua; Helmink, Randolph; Goetz, Robert; Tin, Sammy

    2017-04-01

    The effects of thermo-mechanical processing parameters on the resulting microstructure of an experimental Nickel-based superalloy containing 24 wt pct Co were investigated. Hot compression tests were performed at temperatures ranging from 1293 K to 1373 K (1020 to 1100 °C) and strain rates ranging from 0.0005 to 0.1/s. The mechanically deformed samples were also subject to annealing treatments at sub-solvus 1388 K (1115 °C) and super-solvus 1413 K (1140 °C) temperatures. This investigation sought to quantify and subsequently understand the behavior and evolution of both the grain boundary structure and length fraction of Σ3 twin boundaries in the low stacking fault energy superalloy. Over the range of deformation parameters investigated, the corresponding deformation mechanism map revealed that dynamic recrystallization or dynamic recovery was dominant. These conditions largely promoted post-deformation grain refinement and the formation of annealing twins following annealing. Samples deformed at strain rates of 0.0005 and 0.001/s at 1333 K and 1373 K (1060 °C and 1100 °C) exhibited extensive grain boundary sliding/rotation associated with superplastic flow. Upon annealing, deformation conditions that resulted predominately in superplastic flow were found to provide negligible enhancement of twin boundaries and produced little to no post-deformation grain refinement.

  3. High-temperature γ (FCC/γ′ (L12 Co-Al-W based superalloys

    Directory of Open Access Journals (Sweden)

    Knop Matthias

    2014-01-01

    Full Text Available Interim results from the development of a polycrystalline Co-Al-W based superalloy are presented. Cr has been added to provide oxidation resistance and Ni has then been added to widen and stabilise the γ′ phase field. The alloy presented has a solvus of 1010 °C and a density of 8.7 g cm−3. The room temperature flow stress is over 1000 MPa and this reduces dramatically above 800 °C. The flow stress anomaly is observed. A microstructure with both ∼ 50 nm γ′ produced on cooling and larger 100–200 nm γ′ can be obtained. Isothermal oxidation at 800 °C in air for 200 h gave a mass gain of 0.96 mg cm−2. After hot deformation in the 650–850 °C temperature range, both anti phase boundaries (APBs and stacking faults could be observed. An APB energy of 71 mJ m−2 was measured, which is comparable to that found in commercial nickel superalloys.

  4. Grain Boundary Engineering of a Low Stacking Fault Energy Ni-based Superalloy

    Science.gov (United States)

    McCarley, Joshua; Helmink, Randolph; Goetz, Robert; Tin, Sammy

    2017-02-01

    The effects of thermo-mechanical processing parameters on the resulting microstructure of an experimental Nickel-based superalloy containing 24 wt pct Co were investigated. Hot compression tests were performed at temperatures ranging from 1293 K to 1373 K (1020 to 1100 °C) and strain rates ranging from 0.0005 to 0.1/s. The mechanically deformed samples were also subject to annealing treatments at sub-solvus 1388 K (1115 °C) and super-solvus 1413 K (1140 °C) temperatures. This investigation sought to quantify and subsequently understand the behavior and evolution of both the grain boundary structure and length fraction of Σ3 twin boundaries in the low stacking fault energy superalloy. Over the range of deformation parameters investigated, the corresponding deformation mechanism map revealed that dynamic recrystallization or dynamic recovery was dominant. These conditions largely promoted post-deformation grain refinement and the formation of annealing twins following annealing. Samples deformed at strain rates of 0.0005 and 0.001/s at 1333 K and 1373 K (1060 °C and 1100 °C) exhibited extensive grain boundary sliding/rotation associated with superplastic flow. Upon annealing, deformation conditions that resulted predominately in superplastic flow were found to provide negligible enhancement of twin boundaries and produced little to no post-deformation grain refinement.

  5. Structure property characterization of rheocast and VADER processed IN-100 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, J.J.A.

    1985-01-01

    Two recent solidification processes were applied in production of IN-100 nickel-base superalloy: rheocasting and Vacuum ARc Double Electrode Remelting (VADER). A high vacuum furnace for rheocasting superalloys was built and was used to rheocast ingots under different processing conditions. Processing variables evaluated include stirring speed, isothermal stirring time and volume fraction solid during isothermal stirring. VADER processed IN-100 was purchased from Special Metals Corp. As-cast ingots were subjected to various thermal treatments including hot isostatic pressing and heat treatment. As-cast and thermally treated materials were characterized using optical and scanning electron microscopy and microprobe analysis. Both rheocasting and VADER-processed materials yield fine and equiaxed spherical structures, where the extent of macrosegregation is lesser in comparison to conventionally produced ingot material. In rheocasting, the formation of nondendritic structures is discussed further on the basis of the model of dendrite arm fragmentation. At a constant cooling rate, the grain size and macrosegregation of the as-cast ingot is reduced by increasing the stirring speed, isothermal stirring time or the volume fraction solid during solidification, however, stirring speed has a more pronounced effect on grain refinement and macro-scale chemical homogeneity than the other two variables. The degree of the microsegregation decreases with increasing volume fraction solid and/or isothermal stirring time.

  6. Microstructure Modeling of a Ni-Fe-Based Superalloy During the Rotary Forging Process

    Science.gov (United States)

    Loyda, A.; Hernández-Muñoz, G. M.; Reyes, L. A.; Zambrano-Robledo, P.

    2016-06-01

    The microstructure evolution of Ni-Fe superalloys has a great influence on the mechanical behavior during service conditions. The rotary forging process offers an alternative to conventional bulk forming processes where the parts can be rotary forged with a fraction of the force commonly needed by conventional forging techniques. In this investigation, a numerical modeling of microstructure evolution for design and optimization of the hot forging operations has been used to manufacture a heat-resistant nickel-based superalloy. An Avrami model was implemented into finite element commercial platform DEFORM 3D to evaluate the average grain size and recrystallization during the rotary forging process. The simulations were carried out considering three initial temperatures, 980, 1000, and 1050 °C, to obtain the microstructure behavior after rotary forging. The final average grain size of one case was validated by comparing with results of previous experimental work of disk forging operation. This investigation was aimed to explore the influence of the rotary forging process on microstructure evolution in order to obtain a homogenous and refined grain size in the final component.

  7. Effect of HIP Combined with RHT Process on Creep Damage of DZ125 Superalloy

    Directory of Open Access Journals (Sweden)

    WANG Tian-you

    2017-02-01

    Full Text Available Four different processes of hot isostatic pressing (HIP combined with rejuvenation heat treatments (RHT were adopted to reveal the microstructural evolution of creep damaged DZ125 specimens, finally the mechanical properties were evaluated.The results show that both γ' precipitate degeneration and creep cavities for the creep damaged DZ125 superalloy are found after the pre-endurance damage test.However, the carbided compositions from MC type to M23C6 type or M6C type has not been observed for DZ125.In addition, it is found that the HIP temperature play a dominant role in the cavity healing process for the damaged specimens. The concentrically oriented γ' rafting structure and the incipient melting are observed at 1200℃ and 1250℃ respectively.Meanwhile, it is found that the appropriate HIP schedule adopted can effectively avoid the internal recrystallization for the directionally solidified nickel-based superalloy DZ125. The appropriate HIP schedule combined with RHT process can successfully restore the microstructure induced by creep damage and recover the degraded micro-hardness to the original one, in addition improve the creep rupture life.

  8. A Computer Simulation Study of the Effects of Anions on Nickel Carbonate Crystallization Process%计算机模拟阴离子对碳酸镍结晶过程的影响

    Institute of Scientific and Technical Information of China (English)

    刘昉; Nora H.de Leeuw; 张昭

    2009-01-01

    Crystallization behaviors of nickel carbonate in different solutions are investigated via atomistic simulation technique. Simulation results show that the effect of hydration on the surface enables surface more stable and morphology more regular. The interaction between SO_4~(2-) and crystal surface is strong but SO_4~(2-) has little effect on the crystal morphology. Cl~- has relatively weaker interaction with the surface but makes the crystal morphology irregular. Only dominant (104) face is expressed in each mentioned cases. The simulation results are in good agreement with experiments.%本文采用原子模拟技术,研究了不同溶液中碳酸镍的结晶行为.结果表明,水化作用使碳酸镍晶体更稳定,形貌更规整.杂质阴离子SO_4~(2-)与碳酸镍品体表面的作用力较强,但对其形貌影响不大.Cl~-对表面的作用力较弱,但使晶体形貌更不规则.在模拟的几种情况中,碳酸镍的(104)晶面均是最主要的显露面.模拟结果能与实验现象很好吻合.

  9. Effect of Zr addition on precipitates in K4169 superalloy

    National Research Council Canada - National Science Library

    Li Yamin Liu Hongjun Liu Jie Wang Zhipeng Hao Yuan

    2012-01-01

    In order to investigate the effect of Zr addition on the precipitations of K4169 superalloy, a manual electric arc furnace was used to prepare the superalloy with different Zr addition from 0.03wt.% to 0.07wt...

  10. 75 FR 67100 - Superalloy Degassed Chromium From Japan

    Science.gov (United States)

    2010-11-01

    ... COMMISSION Superalloy Degassed Chromium From Japan AGENCY: United States International Trade Commission... chromium from Japan. SUMMARY: The Commission hereby gives notice that it has instituted a review pursuant... revocation of the antidumping duty order on superalloy degassed chromium from Japan would be likely to lead...

  11. Technology of High-speed Direct Laser Deposition from Ni-based Superalloys

    Science.gov (United States)

    Klimova-Korsmik, Olga; Turichin, Gleb; Zemlyakov, Evgeniy; Babkin, Konstantin; Petrovsky, Pavel; Travyanov, Andrey

    Recently, additive manufacturing is the one of most perspective technologies; it can replace conventional methods of casting and subsequent time-consuming machining. One of the most interesting additive technologies - high-speed direct laser deposition (HSDLD) allows realizing heterophase process during the manufacturing, which there is process takes place with a partial melting of powder. This is particularly important for materials, which are sensitive to strong fluctuations of temperature treatment regimes, like nickel base alloys with high content of gamma prime phase. This alloys are interested for many industrial areas, mostly there are used in engine systems, aircraft and shipbuilding, aeronautics. Heating and cooling rates during the producing process determine structure and affect on its properties. Using HSDLD process it possible to make a products from Ni superalloys with ultrafine microstructure and satisfactory mechanical characteristics without special subsequent heatreatment.

  12. On the precipitation sequence in a Ni-based superalloy: A Coincidence Doppler Broadening study

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, C.E. [IFIMAT, UNCentro and CONICET, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto 399, B7000GHG Tandil (Argentina); Santos, G. [NIECyT, UNCentro, Pinto 399, B7000GHG Tandil (Argentina); Petkov, M. [Jet Propulsion Lab, California Institute of Technology, Pasadena, CA 91109 (United States); Lynn, K.G. [Department of Physics, Washington State University, Pullman WA 99164-2814 (United States)

    2007-07-01

    The precipitation sequence at 700 C of the Ni{sub 3}(Ti,Al)-type ordered {gamma}' phase in the commercial nickel-based superalloy Inconel X-750 was investigated using Coincidence Doppler Broadening (CDB) technique. The results obtained are discussed in terms of positron annihilation in two well-defined states: one corresponding to the matrix ({gamma} phase) and a second related to the {gamma}' precipitates. Between these two aging stages, CDB distributions corresponding to selected intermediate aging treatments could be presented exactly, within the experimental scatter, as a linear combination of the {gamma} and {gamma}' signatures. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Development of superalloys by powder metallurgy for use at 1000 - 1400 F

    Science.gov (United States)

    Calhoun, C. D.

    1971-01-01

    Consolidated powders of four nickel-base superalloys were studied for potential application as compressor and turbine discs in jet engines. All of the alloys were based on the Rene' 95 chemistry. Three of these had variations in carbon and A12O3 contents, and the fourth alloy was chemically modified to a higher volume fraction. The A12O3 was added by preoxidation of the powders prior to extrusion. Various levels of four experimental factors (1) alloy composition, (2) grain size, (3) thermomechanical processing, and (4) room temperature deformation plus final age were evaluated by tensile and stress rupture testing at 1200 F. Various levels of the four factors were assumed in order to construct the statistically-designed experiment, but the actual levels investigated were established in preliminary studies that preceded the statistical process development study.

  14. Inclusion size effect on the fatigue crack propagation mechanism and fracture mechanics of a superalloy

    Science.gov (United States)

    Denda, Takeshi; Bretz, Perter L.; Tien, John K.

    1992-02-01

    Low cycle fatigue life of nickel-base superalloys is enhanced as a consequence of inclusion reduction in the melt process; however, the functional dependencies between fatigue characteristics and inclusions have not been well investigated. In this study, the propagation mechanism of the fatigue crack initiated from inclusions is examined in fine-grained IN718, which is a representative turbine disc material for jet engines. There is a faceted-striated crack transition on the fracture surfaces. This faceted-striated transition also appears in the da/dN vs crack length curves. It is observed that the faceted crack propagation time can be more than 50 pct of total lifetime in the low cycle fatigue test. The significance of inclusion size effect is explained on the premise that the faceted fatigue crack propagation time scales with the inclusion size, which is taken as the initial crack length. A predictive protocol for determining inclusion size effect is given.

  15. High temperature creep properties of directionally solidified CM-247LC Ni-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, Mau-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Jian, Sheng-Rui, E-mail: srjian@gmail.com [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Yeh, An-Chou [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Kuo, Chen-Ming [Department of Mechanical and Automation Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Juang, Jenh-Yih [Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2016-02-08

    This study explores the effects of cooling rate after solution heat treatment on the high temperature/low stress (982 °C/200 MPa) creep properties of CM-247LC Nickel base superalloy. Cooling rate was controlled by blowing argon gas, air cooling, and furnace cooling, which, in turn, gave rise to corresponding cooling rates (from 1260 °C to 800 °C) of 18.7, 7.4, and 0.19 °C/s, respectively. The results indicated that higher cooling rate from the solution heat treatment temperature led to finer γ′ precipitates and much improved tertiary creep as well as rupture life time in high-temperature creep test. The microstructural analyses using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that finer γ′ precipitates and narrower γ channel width could result in denser rafting structure which might have hindered the climb of dislocations across the precipitates rafts.

  16. Study on the hot corrosion behavior of a cast Ni-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Guo, J.T.; Zhang, J.; Yuan, C.; Zhou, L.Z.; Hu, Z.Q. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

    2010-07-01

    Hot corrosion behavior of Nickel-base cast superalloy K447 in 90% Na{sub 2}SO{sub 4} + 10% NaCl melting salt at 850 C and 900 C was studied. The hot corrosion kinetic of the alloy follows parabolic rate law under the experimental conditions. The external layer is mainly Cr{sub 2}O{sub 3} scale which is protective to the alloy, the intermediate layer is the Ti-rich phase, and the internal layer is mainly the international oxides and sulfides. With increased corrosion time and temperature, the oxide scales are gradually dissolved in the molten salt and then precipitate as a thick and non-protective scale. Chlorides cause the formation of volatile species, which makes the oxide scale disintegrate and break off. The corrosion kinetics and morphology examinations tend to support the basic dissolution model for hot corrosion mechanisms. (orig.)

  17. Impact of magnetic fluctuations on lattice excitations in fcc nickel.

    Science.gov (United States)

    Körmann, Fritz; Ma, Pui-Wai; Dudarev, Sergei L; Neugebauer, Jörg

    2016-02-24

    The spin-space averaging formalism is applied to compute atomic forces and phonon spectra for magnetically excited states of fcc nickel. Transverse and longitudinal magnetic fluctuations are taken into account by a combination of magnetic special quasi random structures and constrained spin-density-functional theory. It turns out that for fcc Ni interatomic force constants and phonon spectra are almost unaffected by both kinds of spin fluctuations. Given the computational expense to simulate coupled magnetic and atomic fluctuations, this insight facilitates computational modeling of magnetic alloys such as Ni-based superalloys.

  18. Microwave dielectric properties of nanostructured nickel ferrite

    Indian Academy of Sciences (India)

    John Jacob; M Abdul Khadar; Anil Lonappan; K T Mathew

    2008-11-01

    Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured nickel ferrite samples of three different average grain sizes and those of two sintered samples were studied. The parameters like dielectric constant, dielectric loss and heating coefficient of the nanoparticles samples are studied in the frequency range from 2.4 to 4 GHz. The values of these parameters are compared with those of sintered pellets of the same samples. All these parameters show size dependent variations.

  19. Crystal structure of [5-n-butyl-10-(2,5-dimethoxyphenyl-2,3,7,8,13,12,17,18-octaethylporphyrinato]nickel(II

    Directory of Open Access Journals (Sweden)

    Keith J. Flanagan

    2015-11-01

    Full Text Available The asymmetric unit of the title nickel(II porphyrin, [Ni(C48H60N4O2], contains one independent molecule. The average Ni—N bond length is 1.917 (13 Å. The molecules are arranged in a closely spaced lattice structure in which neighbouring porphyrins are oriented in inversion-related dimers. The nickel(II porphyrin is characterized by a significant degree of a ruffled (B1u conformation with small contributions from saddle (B2u and wave (y [Eg(y], as determined using normal structural decomposition. Disorder in the 2,5-dimethoxyphenyl substituent was modelled over two positions with a 60% occupancy for the major moiety. One of the ethyl groups is also disordered over two positions and was modelled with the major moiety being present in 51.3% occupancy.

  20. 硫酸盐结晶法分离富集红土型镍矿酸溶浸出液中镍的实验研究%The separation and enrichment of nickel from leachate of nickeliferous laterite by using sulfate crystallization

    Institute of Scientific and Technical Information of China (English)

    王玲; 鲁安怀; 宋晓良; 李艳; 王长秋

    2011-01-01

    红土型镍矿中镍的常压酸溶浸出是近年来国际上研究的热点.本文对红土型镍矿常压硫酸浸出液中镍的分离富集进行了初步的实验研究.不同条件的硫酸盐结晶实验表明,红土镍矿硫酸常压浸出液硫酸盐结晶析出晶体主要为MgSO4·H2O.析出晶体中除了金属元素Mg,还有少量的Fe和Ni,并且Fe/Ni较原矿中大大缩小.该硫酸盐析出晶体利于后续处理中金属Ni的进一步富集回收.利用硫酸盐结晶过程富集与回收红土型镍矿常压硫酸浸出液中镍的方法,既减少能源消耗,又有利于环境保护,是一种简单易行且成本低廉的绿色生产工艺.%In recent years, lots of research work has been carried out for nickel recovery from the nickeliferous laterite through atmospheric acid leaching. The separation and enrichment of nickel in the leachate from the atmospheric acid leaching of the nickeliferous laterite was preliminarily investigated in laboratory. A new idea that sulfate crystallization can be used to separate and enrich the nickel within nickeliferous laterite is presented in this paper, which is beneficial to the nickel recovery from the nickeliferous laterite. The sulfate crystallization experiments under different conditions indicate that the crystals crystallized from the atmospheric sulfuric acid leachate of nickeliferous laterite are mainly MgSCVHbO. More significantly, the ratio of Fe and Ni is reduced greatly in the solid solution, which is conducive to the further purification and recovery of the nickel, though it is not effective to separate the Fe and Ni in the liquor by the simple sulfate crystallization. The utilization of sulfate crystallization to separate and enrich the nickel of nickeliferous laterite not only reduces the energy consumption but also contributes to the environment. It is thus a simple and economical industrial method. It is feasible to separate and recover the nickel from the atmospheric sulfuric acid