High-temperature deformation of B2 NiAl-base alloys

International Nuclear Information System (INIS)

Lee, I.G.; Ghosh, A.K.

1994-01-01

The high-temperature deformation behavior of three rapidly solidified and processed NiAl-base alloys--NiAl, NiAl containing 2 pct TiB 2 , and NiAl containing 4 pct HfC--have been studied and their microstructural and textural changes during deformation characterized. Compressions tests were conducted at 1,300 and 1,447 K at strain rates ranging from 10 -6 to 10 -2 s -1 . HfC-containing material showed dispersion strengthening as well as some degree of grain refinement over NiAl, while TiB 2 dispersoid-containing material showed grain refinement as well as secondary recrystallization and did not improve high-temperature strength. Hot-pack rolling was also performed to develop thin sheet materials (1.27-mm thick) and from these alloys. Without dispersoids, NiAl rolled easily at 1,223 K and showed low flow stress and good ductility during the hot-rolling operation. Rolling of dispersoid-containing alloys was difficult due to strain localization and edge-cracking effects, resulting partly from the high flow stress at the higher strain rate during the rolling operation. Sheet rolling initially produced a {111} texture, which eventually broke into multiple-texture components with severe deformation

Solidification of Al-Sn-Cu Based Immiscible Alloys under Intense Shearing

Science.gov (United States)

Kotadia, H. R.; Doernberg, E.; Patel, J. B.; Fan, Z.; Schmid-Fetzer, R.

2009-09-01

The growing importance of Al-Sn based alloys as materials for engineering applications necessitates the development of uniform microstructures with improved performance. Guided by the recently thermodynamically assessed Al-Sn-Cu system, two model immiscible alloys, Al-45Sn-10Cu and Al-20Sn-10Cu, were selected to investigate the effects of intensive melt shearing provided by the novel melt conditioning by advanced shear technology (MCAST) unit on the uniform dispersion of the soft Sn phase in a hard Al matrix. Our experimental results have confirmed that intensive melt shearing is an effective way to achieve fine and uniform dispersion of the soft phase without macro-demixing, and that such dispersed microstructure can be further refined in alloys with precipitation of the primary Al phase prior to the demixing reaction. In addition, it was found that melt shearing at 200 rpm and 60 seconds will be adequate to produce fine and uniform dispersion of the Sn phase, and that higher shearing speed and prolonged shearing time can only achieve minor further refinement.

Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy.

Science.gov (United States)

Dang, B; Zhang, X; Chen, Y Z; Chen, C X; Wang, H T; Liu, F

2016-08-09

Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

Research into Oil-based Colloidal-Graphite Lubricants for Forging of Al-based Alloys

International Nuclear Information System (INIS)

Petrov, A.; Petrov, P.; Petrov, M.

2011-01-01

The presented paper describes the topical problem in metal forging production. It deals with the choice of an optimal lubricant for forging of Al-based alloys. Within the scope of the paper, the properties of several oil-based colloidal-graphite lubricants were investigated. The physicochemical and technological properties of these lubricants are presented. It was found that physicochemical properties of lubricant compositions have an influence on friction coefficient value and quality of forgings.The ring compression method was used to estimate the friction coefficient value. Hydraulic press was used for the test. The comparative analysis of the investigated lubricants was carried out. The forging quality was estimated on the basis of production test. The practical recommendations were given to choose an optimal oil-based colloidal-graphite lubricant for isothermal forging of Al-based alloy.

United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

Institute of Scientific and Technical Information of China (English)

韩延峰; 刘相法; 王海梅; 王振卿; 边秀房; 张均艳

2003-01-01

The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated. It is foundthat excellent modification effect can be obtained by the addition of this new type of A1-P master alloy into Al-24Simelt and the average primary Si grain size is decreased below 47 μm from original 225 μm. It is also found that theTiC particles in the melt coming from Al8Ti2C can improve the modification effect of the Al-P master alloy. Whenthe content of TiC particles in the Al-24Si melt is 0.03 %, the improvement reaches the maximum and keeps steadywith increasing content of TiC particles. Modification effect occurs at 50 min after the addition of the Al-P master al-loy and TiC particles, and keeps stable with prolonging holding time.

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

International Nuclear Information System (INIS)

Qin, Gaowu W.; Ren Yuping; Huang Wei; Li Song; Pei Wenli

2010-01-01

Graphical abstract: Display Omitted Research highlights: The ε-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8 Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure ε-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 o C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure ε-AlMn, γ 2 -Al 8 Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ε-AlMn phase in the Mn-Al alloys, not the γ 2 -Al 8 Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn-Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 o C.

A Study on Development of High Strength Al-Zn Based alloy for Die Casting Ⅲ

Energy Technology Data Exchange (ETDEWEB)

Shin, Sang-Soo; Park, Ik-Min [Pusan National University, Busan (Korea, Republic of); Yeom, Gil-Young; Lim, Kyoung-Mook [Korea Institute of Industrial Technology, Incheon (Korea, Republic of); Son, Hyun-Jin [Oh-Sung Co. Ltd., Siheung (Korea, Republic of)

2015-09-15

In this study, the microstructural evolution and various characteristics of Al-20⁓45wt%Zn alloys were investigated. In terms of microstructure, as the amount of Zn addition to the alloys increased, the α-phase size decreased and the α+η non-equilibrium solidification phase fraction increased. Also, increasing Zn content improved the wear resistance of the alloys, but reduced the damping capacity and toughness of the alloys. Their physical properties of the Al-Zn alloy with high Zn content, specifically the wear resistance and toughness, were superior to those of commercial ALDC12 alloys for die-casting. Based on these results, we considered the possibility of application of the developed Al-Zn alloy as a structural material.

A Study on Development of High Strength Al-Zn Based alloy for Die Casting Ⅲ

International Nuclear Information System (INIS)

Shin, Sang-Soo; Park, Ik-Min; Yeom, Gil-Young; Lim, Kyoung-Mook; Son, Hyun-Jin

2015-01-01

In this study, the microstructural evolution and various characteristics of Al-20⁓45wt%Zn alloys were investigated. In terms of microstructure, as the amount of Zn addition to the alloys increased, the α-phase size decreased and the α+η non-equilibrium solidification phase fraction increased. Also, increasing Zn content improved the wear resistance of the alloys, but reduced the damping capacity and toughness of the alloys. Their physical properties of the Al-Zn alloy with high Zn content, specifically the wear resistance and toughness, were superior to those of commercial ALDC12 alloys for die-casting. Based on these results, we considered the possibility of application of the developed Al-Zn alloy as a structural material.

Advanced Class of FML on the Base Al-Li Alloy 1441 with Lower Density

Science.gov (United States)

Antipov, V. V.; Senatorova, O. G.; Lukina, N. F.

Structure, composition, properties combination of specimens and components, a number of technological parameters for production of advanced FML based on high-modulus Al-Li 1441 alloy (E 79 GPa) with reduced density (d 2.6 g/m3) and optimized adhesive prepreg reinforced with high-strength high-modulus VMP glass fibres are described. Service life 1441 alloy provides the possibility of manufacture of thin sheets (up to 0.3 mm), clad and unclad. Moreover, some experience on the usage of 1441 T1, T11 sheets and shapes in Be 200 and Be 103 aircraft was accumulated. The class of FML materials based on Al-Li alloy provide an 5% improvement in weight efficiency and stiffness of skin structures as compared with those made from FML with conventional Al-Cu-Mg (2024T3 a.o.) and Al-Zn-Mg-Cu (7475T76 a.o.) alloys.

Chemical interaction of the In-Ga eutectic with Al and Al-base alloys

International Nuclear Information System (INIS)

Trenikhin, M.V.; Bubnov, A.V.; Duplyakin, V.K.; Nizovskij, A.I.

2006-01-01

The chemical interaction of the indium-gallium eutectic with Al and Al-base alloys is studied by X-ray diffraction, optical microscopy, and electron microscopy. Experimental data are presented that shed light on the reaction mechanism and the diffusion processes responsible for the subsequent disintegration of the material and its dissolution in water. Mechanical tests show that the activation of aluminum leads to a transition from plastic to brittle fracture [ru

Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

Energy Technology Data Exchange (ETDEWEB)

Qin, Gaowu W., E-mail: qingw@smm.neu.edu.c [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China); Ren Yuping; Huang Wei; Li Song; Pei Wenli [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China)

2010-10-08

Graphical abstract: Display Omitted Research highlights: The {epsilon}-AlMn phase acts as the heterogeneous nucleus of {alpha}-Mg phase during the solidification of the AZ31 Mg alloy, not the {gamma}-Al{sub 8}Mn{sub 5} phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure {epsilon}-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 {sup o}C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure {epsilon}-AlMn, {gamma}{sub 2}-Al{sub 8}Mn{sub 5} or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the {epsilon}-AlMn phase in the Mn-Al alloys, not the {gamma}{sub 2}-Al{sub 8}Mn{sub 5} phase. The grain size of AZ31 Mg alloy is about 91 {mu}m without any addition of Mn-Al alloys, but remarkably decreases to {approx}55 {mu}m with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to {approx}53 {mu}m, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 {sup o}C.

The corrosion behaviour of Zr3Al-based alloys

International Nuclear Information System (INIS)

Murphy, E.V.; Wieler, R.

1977-07-01

The corrosion resistance of several zirconium-aluminum alloys with aluminum contents ranging from 7.6 to 9.6 wt% was examined in 300 deg C and 325 deg C water, 350 deg C and 400 deg C steam and in air and wet CO 2 at 325 deg C and 400 deg C. In the transformed alloys there are three phases present, αZr, Zr 2 Al and Zr 3 Al of which the αZr phase is the least corrosion resistant. The most important factor controlling the corrosion behaviour of these alloys was found to be the size, distribution and amount of the αZr phase in the transformed alloys, which in turn was dependent upon the microstructural scale of the untransformed alloys

Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

Science.gov (United States)

Stein, Frank; Philips, Noah

2018-03-01

High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

Thermo-mechanical processing (TMP) of Ti-48Al-2Nb-2Cr based alloys

International Nuclear Information System (INIS)

Fuchs, G.E.

1995-02-01

The effects of heat treatment and deformation processing on the microstructures and properties of γ-TiAl based alloys produced by ingot metallurgy (I/M) and powder metallurgy (P/M) techniques were examined. The alloy selected for this work is the second generation γ-TiAl based alloy -- Ti-48Al-2Nb-2Cr (at %). Homogenization of I/M samples was performed at a variety of temperatures, followed by hot working by isothermal forging. P/M samples were prepared from gas atomized powders, consolidated by both HIP and extrusion and some of the HIPed material was then hot worked by isothermal forging. The effects of processing, heat treatment and hot working on the microstructures and properties will be discussed

Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Emad M. Elgallad

2016-01-01

Full Text Available This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

Superplastic deformation of P/M and I/M Al-Li based alloys

International Nuclear Information System (INIS)

Lederich, R.J.; Sastry, S.M.L.

1984-01-01

Incremental strain-rate and constant strain-rate cone-forming tests have been carried out at 450-550 C to investigate the superplastic forming characteristics of Al-Li-Cu-Mn, Al-Li-Cu-Mg-Zr, and Al-Li-Zn-Mg alloys processed by powder-metallurgy (P/M) and ingot-metallurgy (I/M) techniques. It is found that P/M Al-Li alloys containing 0.2 pct Zr are inherently superplastically formable without the need for extensive thermomechanical processing. I/M Al-Li alloys containing Zr are also superplastically formable. The mechanical properties of the superplastically formed and solution-treated-and-aged alloys are comparable to those of solution-treated-and-aged alloys before superplastic forming. 6 references

Study on Mg/Al Weld Seam Based on Zn–Mg–Al Ternary Alloy

Directory of Open Access Journals (Sweden)

Liming Liu

2014-02-01

Full Text Available Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA welding. An infrared thermography system was used to measure the temperature of the welding pool during the welding process to investigate the solidification process. It was found that the mechanical properties of the welded joints were improved with the increasing of the Al content in the Zn–xAl filler metals, and when Zn–30Al was used as the filler metal, the ultimate tensile strength could reach a maximum of 120 MPa. The reason for the average tensile strength of the joint increasing was that the weak zone of the joint using Zn–30Al filler metal was generated primarily by α-Al instead of MgZn2. When Zn–40Al was used as the filler metal, a new transition zone, about 20 μm-wide, appeared in the edge of the fusion zone near the Mg base metal. Due to the transition zones consisting of MgZn2- and Al-based solid solution, the mechanical property of the joints was deteriorated.

Microstructure/Oxidation/Microhardness Correlations in Gamma-Based and Tau-Based Al-Ti-Cr Alloys

Science.gov (United States)

Brady, Michael P.; Smialek, J. L.; Humphrey, D. L.

1994-01-01

The relationships between alloy microstructure and air oxidation kinetics and alloy microstructure and microhardness in the Al-Ti-Cr system for exposures at 800 C and 1000 C were investigated. The relevant phases were identified as tau (Ll2), gamma (LIO), r-Al2Ti, TiCrAl (laves), and Cr2AI. Protective alumina formation was associated with tau, Al-rich TiCrAl, and gamma/TiCrAl mixtures. Brittleness was associated with the TiCrAl phase and tau decomposition to A12Ti + Cr2AI. It was concluded that two-phase gamma + TiCrAl alloys offer the greatest potential for oxidation resistance and room temperature ductility in the Al-Ti-Cr system.

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

International Nuclear Information System (INIS)

Sameljuk, A.V.; Neikov, O.D.; Krajnikov, A.V.; Milman, Yu.V.; Thompson, G.E.

2004-01-01

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion

Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

Energy Technology Data Exchange (ETDEWEB)

Schwaighofer, Emanuel, E-mail: emanuel.schwaighofer@unileoben.ac.at [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria); Lindemann, Janny [Chair of Physical Metallurgy and Materials Technology, Brandenburg University of Technology, Konrad-Wachsmann-Allee 17, D-03046 Cottbus (Germany); GfE Fremat GmbH, Lessingstr. 41, D-09599 Freiberg (Germany); Stark, Andreas [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Mayer, Svea [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, A-8700 Leoben (Austria)

2014-09-22

New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s{sup −1} up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti{sub 5}Si{sub 3} silicides and h-type carbides Ti{sub 2}AlC enhance the dynamic recrystallization behavior during

Hot-working behavior of an advanced intermetallic multi-phase γ-TiAl based alloy

International Nuclear Information System (INIS)

Schwaighofer, Emanuel; Clemens, Helmut; Lindemann, Janny; Stark, Andreas; Mayer, Svea

2014-01-01

New high-performance engine concepts for aerospace and automotive application enforce the development of lightweight intermetallic γ-TiAl based alloys with increased high-temperature capability above 750 °C. Besides an increased creep resistance, the alloy system must exhibit sufficient hot-workability. However, the majority of current high-creep resistant γ-TiAl based alloys suffer from poor workability, whereby grain refinement and microstructure control during hot-working are key factors to ensure a final microstructure with sufficient ductility and tolerance against brittle failure below the brittle-to-ductile transition temperature. Therefore, a new and advanced β-solidifying γ-TiAl based alloy, a so-called TNM alloy with a composition of Ti–43Al–4Nb–1Mo–0.1B (at%) and minor additions of C and Si, is investigated by means of uniaxial compressive hot-deformation tests performed with a Gleeble 3500 simulator within a temperature range of 1150–1300 °C and a strain rate regime of 0.005–0.5 s −1 up to a true deformation of 0.9. The occurring mechanisms during hot-working were decoded by ensuing constitutive modeling of the flow curves by a novel phase field region-specific surface fitting approach via a hyperbolic-sine law as well as by evaluation through processing maps combined with microstructural post-analysis to determine a safe hot-working window of the refined TNM alloy. Complementary, in situ high energy X-ray diffraction experiments in combination with an adapted quenching and deformation dilatometer were conducted for a deeper insight about the deformation behavior of the alloy, i.e. phase fractions and texture evolution as well as temperature uncertainties arising during isothermal and non-isothermal compression. It was found that the presence of β-phase and the contribution of particle stimulated nucleation of ζ-Ti 5 Si 3 silicides and h-type carbides Ti 2 AlC enhance the dynamic recrystallization behavior during deformation within

Fabrication and structure of bulk nanocrystalline Al-Si-Ni-mishmetal alloys

International Nuclear Information System (INIS)

Latuch, Jerzy; Cieslak, Grzegorz; Kulik, Tadeusz

2007-01-01

Al-based alloys of structure consisting of nanosized Al crystals, embedded in an amorphous matrix, are interesting for their excellent mechanical properties, exceeding those of the commercial crystalline Al-based alloys. Recently discovered nanocrystalline Al alloys containing silicon (Si), rare earth metal (RE) and late transition metal (Ni), combine high tensile strength and good wear resistance. The aim of this work was to manufacture bulk nanocrystalline alloys from Al-Si-Ni-mishmetal (Mm) system. Bulk nanostructured Al 91-x Si x Ni 7 Mm 2 (x = 10, 11.6, 13 at.%) alloys were produced by ball milling of nanocrystalline ribbons followed by high pressure hot isostating compaction

Bridge approach slabs for Missouri DOT field evaluation of alternative and cost efficient bridge approach slabs.

Science.gov (United States)

2013-05-01

Based on a recent study on cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et : al. 2010) has recommended three new BAS designs for possible implementation by MoDOT namely a) 20 feet cast-inplace : slab with sleeper slab (C...

Detection and distribution of lithium in Mg-Li-Al based alloy by ToF-SIMS

Energy Technology Data Exchange (ETDEWEB)

Kumar, Vinod, E-mail: vkt.meta@mnit.ac.in [Metallurgical and Materials Engineering, MNIT Jaipur, 302017 (India); Adjunct Faculty, Materials Research Centre, MNIT Jaipur, 302017 (India)

2016-12-01

Highlights: • First time, Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) is used to investigate the surface as well as bulk microstructural features of novel Mg-Li-Al based alloy. • There are six multi-oxide layers present within the surface film of LATZ9531R. • Secondary ion imaging by ToF-SIMS with mass contrast effect (including Li) is possible for a multiphase lithium-containing alloy systems. - Abstract: Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) is used to investigate the surface as well as bulk microstructural features of novel Mg-Li-Al based alloy namely Mg-9Li-7Al-3Sn-1Zn (LATZ9531). ToF-SIMS study indicates that there are six multi-oxide layers present within the surface film of LATZ9531. Furthermore, The presence of Li containing phase has been qualitatively confirmed based on the high number of Li-ion counts in SIMS, and the same is verified quantitatively by using electron probe microanalysis (EPMA). The novel approach may be useful to determine the chemical composition of the phases in various alloys which has lighter alloying elements such as lithium.

Effect of molybdenum and chromium additions on the mechanical properties of Fe3Al-based alloys

International Nuclear Information System (INIS)

Sun Yangshan; Xue Feng; Mei Jianping; Yu Xingquan; Zhang Lining

1995-01-01

Iron aluminides based on Fe 3 Al offer excellent oxidation and sulfidation resistance, with lower material cost and density than stainless steels. However, their potential use as structural material has been hindered by limited ductility and a sharp drop in strength above 600 C. Recent development efforts have indicated that adequate engineering ductility of 10--20% and tensile yield strength of as high as 500 MPa can be achieved through control of composition and microstructure. These improved tensile properties make Fe 3 Al-based alloys more competitive against conventional austenic and ferritic steels. The improvement of high temperature mechanical properties has been achieved mainly by alloying processes. Molybdenum has been found to be one of the most important alloying elements for strengthening Fe 3 Al-based alloys at high temperatures. However, the RT(room temperature) ductility decreases with the increase of a molybdenum addition. On the other hand, a chromium addition to Fe 3 Al-based alloys is very efficient for improving RT ductility but not beneficial to yield strength at temperatures to 800 C. The purpose of the present paper is to report the effects of combined additions of molybdenum and chromium on mechanical properties at ambient temperature and high temperature of 600 C

Grain refinement of 7075Al alloy microstructures by inoculation with Al-Ti-B master alloy

Science.gov (United States)

Hotea, V.; Juhasz, J.; Cadar, F.

2017-05-01

This paper aims to bring some clarification on grain refinement and modification of high strength alloys used in aerospace technique. In this work it was taken into account 7075 Al alloy, and the melt treatment was carried out by placing in the form of master alloy wire ternary AlTiB the casting trough at 730°C. The morphology of the resulting microstructures was characterized by optical microscopy. Micrographs unfinished and finished with pre-alloy containing ternary Al5Ti1B evidence fine crystals, crystal containing no columnar structure and highlights the size of the dendrites, and intermetallic phases occurring at grain boundaries in Al-Zn-Mg-Cu alloy. It has been found that these intermetallic compounds are MgZn2 type. AlTiB master alloys finishing ensures a fine eutectic structure, which determines the properties of hardware and improving the mechanical properties of aluminum alloys used in aeronautical engineering.

Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

Portevin-Le Chatelier effect in rolled Al-Li based alloys

International Nuclear Information System (INIS)

Mizera, J.; Kurzydlowski, K.J.

2001-01-01

Studied were carried out on the Portevin-Le Chatelier (PLC) effect in binary, ternary and quaternary Al-Li alloys and in the commercial 8090 alloy. The correlation between the serration characteristic, the rolling degree and the straining orientation has been analysed. The fact that the presence of the Cu-containing precipitates intensifies the PLC effects suggests, that these are primarily related to the interactions between the dislocations and the semi-coherent T 1 (Al 2 CuLi) precipitates. The analysis of the PLC effect in Al-Li alloys shows that the serrations in the stress-strain curve exhibit a profound degree of anisotropy. Most pronounced PLC effects are observed along the rolling and transverse directions. (author)

Surface modification of 5083 Al alloy by electrical discharge alloying processing with a 75 mass% Si-Fe alloy electrode

Energy Technology Data Exchange (ETDEWEB)

Stambekova, Kuralay [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan (China); Lin, Hung-Mao [Department of Mechanical Engineering, Far East University, No. 49, Zhonghua Rd., Xinshi Dist., Tainan City 74448, Taiwan (China); Uan, Jun-Yen, E-mail: jyuan@dragon.nchu.edu.tw [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 40227, Taiwan (China)

2012-03-01

This study experimentally investigates the surface modification of 5083 Al alloy by the electrical discharge alloying (EDA) process with a Si-Fe alloy as an electrode. Samples were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), micro-hardness and corrosion resistance tests. The micro-hardness of EDA alloyed layer was evidently higher than that of the base metal (5083 Al alloy). The TEM results show that the matrix of the alloyed layer has an amorphous-like structure; the matrix contains fine needle-like Si particles, block-like Si particles and nano-size Al{sub 4.5}FeSi and Al{sub 13}Fe{sub 4} particles. The TEM results support experimental results for the high hardness of the alloyed layer. Moreover, the EDA alloyed layer with composite microstructures has good corrosion resistance in NaCl aqueous solution.

Vanadium Influence on Iron Based Intermetallic Phases in AlSi6Cu4 Alloy

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Bolibruchová D.

2014-10-01

Full Text Available Negative effect of iron in Al-Si alloys mostly refers with iron based intermetallic phases, especially Al5FeSi phases. These phases are present in platelet-like forms, which sharp edges are considered as main cracks initiators and also as contributors of porosity formation. In recent times, addition of some elements, for example Mn, Co, Cr, Ni, V, is used to reduce influence of iron. Influence of vanadium in aluminium AlSi6Cu4 alloy with intentionally increased iron content is presented in this article. Vanadium amount has been graduated and chemical composition of alloy has been analysed by spectral analysis. Vanadium influence on microstructural changes was evaluated by microstructural analysis and some of intermetallic particles were reviewed by EDX analysis.

High temperature steam oxidation of Al3Ti-based alloys for the oxidation-resistant surface layer on Zr fuel claddings

International Nuclear Information System (INIS)

Park, Jeong-Yong; Kim, Il-Hyun; Jung, Yang-Il; Kim, Hyun-Gil; Park, Dong-Jun; Choi, Byung-Kwon

2013-01-01

We investigated the feasibility to apply Al 3 Ti-based alloys as the surface layer for improving the oxidation resistance of Zr fuel claddings under accident conditions. Two types of Al 3 Ti-based alloys with the compositions of Al–25Ti–10Cr and Al–21Ti–23Cr in atomic percent were prepared by arc-melting followed by homogenization annealing at 1423 K for 48 h. Al–25Ti–10Cr alloy showed an L1 2 quasi-single phase microstructure with a lot of needle-shaped minor phase and pores. Al–21Ti–23Cr alloy consisted of an L1 2 matrix and Cr 2 Al as the second phase. Al 3 Ti-based alloys showed an extremely low oxidation rate in a 1473 K steam for up to 7200 s when compared to Zircaloy-4. Both alloys exhibited almost the same oxidation rate in the early stage of oxidation, but Al–25Ti–10Cr showed a little lower oxidation rate after 4000 s than Al–21Ti–23Cr. The difference in the oxidation rate between two types of Al 3 Ti-based alloys was too marginal to distinguish the oxidation behavior of each alloy. The resultant oxide exhibited almost the same characteristics in both alloys even though the microstructure was explicitly distinguished from each other. The crystal structure of the oxide formed up to 2000 s was identified as Al 2 O 3 in both alloys. The oxide morphology consisted of columnar grains whose length was almost identical to the average oxide thickness. On the basis of the results obtained, it is considered that Al 3 Ti-based alloy is one of the promising candidates for the oxidation-resistant surface layer on Zr fuel claddings

Transformation processes during annealing of Al-amorphous alloys

International Nuclear Information System (INIS)

Petrescu, N.; Petrescu, M.; Calin, M.; Jianu, A.D.; Fecioru, M.

1993-01-01

As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.)

Transformation processes during annealing of Al-amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Petrescu, N. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Petrescu, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Calin, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania)); Jianu, A.D. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) IFTM-Bucharest (Romania)); Fecioru, M. (Polytechnic Inst. Bucharest, Faculty Materials Science and Engineering, Bucharest (Romania) DACIA Enterprise-Bucharest (Romania))

1993-11-01

As the amorphous aluminum alloys represent the newest achievement in rapid solidification of Al-based high strength heat resistent materials, a study was undertaken on the amorphous alloys in the Al-RE-TM system, the rare-earth metal being a lanthanide mixture and the transition metal a Ni-Fe substitution in definite proportions. The decomposition on heating of the most highly alloyed amorphous alloy in the investigated series is characterized by differential thermal analysis, electron microscopy and X-ray diffraction. (orig.).

Strain ageing and yield plateau phenomena in γ-TiAl based alloys containing boron

International Nuclear Information System (INIS)

Cheng, T.T.; Bate, P.S.; Botten, R.R.; Lipsitt, H.A.

1999-01-01

There has been considerable interest over the past few years in γ-TiAl based alloys since they offer a combination of low density and useful mechanical properties at temperatures higher than those possible with conventional titanium alloys. However, there are still serious limitations to their use in engineering components due to their limited ductility and fracture toughness. Much of the recent work has been focused on improving the room temperature ductility of these materials, and a significant part of the work has been involved with studying the effects of thermo-mechanical processing (TMP) and alloying. One of the alloying additions which has received much attention is boron. Addition of boron (≥0.5 at.%) leads to refined as-cast grain structures and can increase the strength and ductility of these alloys. If boron does segregate to grain boundaries, it would be expected that segregation would also occur at dislocations, which can result in solute locking and yield point phenomena. Nakano and Umakoshi's results show some signs of this, with regions of distinct upward curvature in stress-strain curves for boron-containing material, although the flow stress was always increasing with strain. Evidence of strain ageing in TiAl alloys containing boron has also been reported by Wheeler et al., and the work reported here also suggests that boron can act to produce solute locking of glide dislocations in a different class of near γ-TiAl alloys

Tribological properties of Al 7075 alloy based composites strengthened with Al2O3 fibres

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K. Naplocha

2011-04-01

Full Text Available Wear resistance of 7075 aluminium alloy based composite materials reinforced with Al2O3 Saffil fibres was investigated. The measurementsof wear were performed applying the pin-on-disc method at dry friction conditions with the gray iron counterpart. The effects ofpressure of composite samples on the counterpart made of gray iron and the orientation of fibers in relation to the friction surface on wear rate were determined. The materials were produced by squeeze casting method where 80-90% porous ceramic preform were infiltrated.After T6 heat treatment hardness increased about 50-60% both for unreinforced alloy and composites containing strengthening Saffilfibres. Wear resistance of composite materials in relation to the unreinforced 7075 alloy was slightly worse at lower pressure of 0.8 MPa. Under higher pressure of 1.2 MPa wear resistance of unreinforced 7075 alloy was even better whereas no effect of orientation of fibers on wear in composite materials was observed. Additionally, significant wear of counterface in the presence of debris with fragmented Al2O3 fibres as abrasives was observed. Wear resistance improvement of composite materials was obtained when with alumina Saffil fibres Carbon C fibres in the preforms were applied.

Investigation of new type Cu-Hf-Al bulk glassy alloys

International Nuclear Information System (INIS)

Nagy, E; Ronto, V; Solyom, J; Roosz, A

2009-01-01

In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu 49 Hf 42 Al 9 , Cu 46 Hf 45 Al 9 , Cu 50 Hf 42.5 Al 7.5 and Cu 50 Hf 45 Al 5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

Self-forming Al oxide barrier for nanoscale Cu interconnects created by hybrid atomic layer deposition of Cu–Al alloy

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Park, Jae-Hyung; Han, Dong-Suk; Kang, You-Jin [Division of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Shin, So-Ra; Park, Jong-Wan, E-mail: jwpark@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

2014-01-15

The authors synthesized a Cu–Al alloy by employing alternating atomic layer deposition (ALD) surface reactions using Cu and Al precursors, respectively. By alternating between these two ALD surface chemistries, the authors fabricated ALD Cu–Al alloy. Cu was deposited using bis(1-dimethylamino-2-methyl-2-butoxy) copper as a precursor and H{sub 2} plasma, while Al was deposited using trimethylaluminum as the precursor and H{sub 2} plasma. The Al atomic percent in the Cu–Al alloy films varied from 0 to 15.6 at. %. Transmission electron microscopy revealed that a uniform Al-based interlayer self-formed at the interface after annealing. To evaluate the barrier properties of the Al-based interlayer and adhesion between the Cu–Al alloy film and SiO{sub 2} dielectric, thermal stability and peel-off adhesion tests were performed, respectively. The Al-based interlayer showed similar thermal stability and adhesion to the reference Mn-based interlayer. Our results indicate that Cu–Al alloys formed by alternating ALD are suitable seed layer materials for Cu interconnects.

Self-forming Al oxide barrier for nanoscale Cu interconnects created by hybrid atomic layer deposition of Cu–Al alloy

International Nuclear Information System (INIS)

Park, Jae-Hyung; Han, Dong-Suk; Kang, You-Jin; Shin, So-Ra; Park, Jong-Wan

2014-01-01

The authors synthesized a Cu–Al alloy by employing alternating atomic layer deposition (ALD) surface reactions using Cu and Al precursors, respectively. By alternating between these two ALD surface chemistries, the authors fabricated ALD Cu–Al alloy. Cu was deposited using bis(1-dimethylamino-2-methyl-2-butoxy) copper as a precursor and H 2 plasma, while Al was deposited using trimethylaluminum as the precursor and H 2 plasma. The Al atomic percent in the Cu–Al alloy films varied from 0 to 15.6 at. %. Transmission electron microscopy revealed that a uniform Al-based interlayer self-formed at the interface after annealing. To evaluate the barrier properties of the Al-based interlayer and adhesion between the Cu–Al alloy film and SiO 2 dielectric, thermal stability and peel-off adhesion tests were performed, respectively. The Al-based interlayer showed similar thermal stability and adhesion to the reference Mn-based interlayer. Our results indicate that Cu–Al alloys formed by alternating ALD are suitable seed layer materials for Cu interconnects

Modeling of mechanical properties of as-cast Mg-Li-Al alloys based on PSO-BP algorithm

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Li Ming

2012-05-01

Full Text Available Artificial neural networks have been widely used to predict the mechanical properties of alloys in material research. This study aims to investigate the implicit relationship between the compositions and mechanical properties of as-cast Mg-Li-Al alloys. Based on the experimental collection of the tensile strength and the elongation of representative Mg-Li-Al alloys, a momentum back-propagation (BP neural network with a single hidden layer was established. Particle swarm optimization (PSO was applied to optimize the BP model. In the neural network, the input variables were the contents of Mg, Li and Al, and the output variables were the tensile strength and the elongation. The results show that the proposed PSO-BP model can describe the quantitative relationship between the Mg-Li-Al alloy’s composition and its mechanical properties. It is possible that the mechanical properties to be predicted without experiment by inputting the alloy composition into the trained network model. The prediction of the influence of Al addition on the mechanical properties of as-cast Mg-Li-Al alloys is consistent with the related research results.

The use of Nb in rapid solidified Al alloys and composites

Energy Technology Data Exchange (ETDEWEB)

Audebert, F., E-mail: metal@fi.uba.ar [Advanced Materials Group, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, Ciudad de Buenos Aires 1063 (Argentina); Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Department of Mechanical Engineering and Mathematical Sciences, Oxford Brookes University, Wheatley Campus, OX33 1HX Oxford (United Kingdom); Galano, M. [Department of Materials, University of Oxford, Parks Road, OX1 3PH Oxford (United Kingdom); Saporiti, F. [Advanced Materials Group, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, Ciudad de Buenos Aires 1063 (Argentina)

2014-12-05

Highlights: • The use of Nb in RS Al alloys and composites has been reviewed. • Nb was found to improve the GFA of rapid solidified Al–Fe and Al–Ni alloys. • Nb has higher effect in increasing the corrosion resistance than RE in Al–Fe alloys. • Nb improves the stability of the Al–Fe–Cr icosahedral phase. • Nb improves strength, ductility and toughness of nanoquasicrystalline Al matrix composites. - Abstract: The worldwide requirements for reducing the energy consumption and pollution have increased the demand of new and high performance lightweight materials. The development of nanostructured Al-based alloys and composites is a key direction towards solving this demand. High energy prices and decreased availability of some alloying elements open up the opportunity to use non-conventional elements in Al alloys and composites. In this work the application of Nb in rapid solidified Al-based alloys and Al alloys matrix composites is reviewed. New results that clarify the effect of Nb on rapid solidified Al alloys and composites are also presented. It is observed that Nb stabilises the icosahedral Al–Fe/Cr clusters, enhances the glass forming ability and shifts the icosahedral phase decomposition towards higher temperatures. Nb provides higher corrosion resistance with respect to the pure Al and Al–Fe–RE (RE: rare earth) alloys in the amorphous and crystalline states. The use of Nb as a reinforcement to produce new Al alloy matrix composites is explored. It is observed that Nb provides higher strength, ductility and toughness to the nanoquasicrystalline matrix composite. Nb appears as a new key element that can improve several properties in rapid solidified Al alloys and composites.

Formation and structure of nanocrystalline Al-Mn-Ni-Cu alloys

International Nuclear Information System (INIS)

Latuch, J.; Krasnowski, M.; Ciesielska, B.

2002-01-01

This paper reports the results of the short investigation on the effect of Cu additions upon the nanocrystallization behaviour of an Al-Mn-Ni alloy. 2 at.% Cu added to the base alloy of Al 85 Mn 10 Ni 5 alloy by substitution for Mn(mischmetal). The control of cooling rate did not cause the formation of nanocrystals of fcc-Al phase. The nanocrystalline structure fcc-Al + amorphous phase in quarternary alloy was obtained by isothermal annealing and continuous heating method, but the last technique is more effective. The volume fraction, lattice parameter, and size of Al-phase were calculated. (author)

Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys

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Guo J.

2015-06-01

Full Text Available Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.

Alloying behavior of iron, gold and silver in AlCoCrCuNi-based equimolar high-entropy alloys

International Nuclear Information System (INIS)

Hsu, U.S.; Hung, U.D.; Yeh, J.W.; Chen, S.K.; Huang, Y.S.; Yang, C.C.

2007-01-01

High-entropy alloys are newly developed alloys that are composed, by definition, of at least five principal elements with concentrations in the range of 5-35 at.%. Therefore, the alloying behavior of any given principal element is significantly affected by all the other principal elements present. In order to elucidate this further, the influence of iron, silver and gold addition on the microstructure and hardness of AlCoCrCuNi-based equimolar alloys has been examined. The as-cast AlCoCrCuNi base alloy is found to have a dendritic structure, of which only solid solution FCC and BCC phases can be observed. The BCC dendrite has a chemical composition close to that of the nominal alloy, with a deficiency in copper however, which is found to segregate and form a FCC Cu-rich interdendrite. The microstructure of the iron containing alloys is similar to that of the base alloy. It is found that both of these aforementioned alloys have hardnesses of about 420 HV, which is equated to their similar microstructures. The as-cast ingot forms two layers of distinct composition with the addition of silver. These layers, which are gold and silver in color, are determined to have a hypoeutectic Ag-Cu composition and a multielement mixture of the other principal elements, respectively. This indicates the chemical incompatibility of silver with the other principal elements. The hardnesses of the gold (104 HV) and silver layers (451 HV) are the lowest and highest of the alloy systems studied. This is attributed to the hypoeutectic Ag-Cu composition of the former and the reduced copper content of the latter. Only multielement mixtures, i.e. without copper segregation, form in the gold containing alloy. Thus, it may be said that gold acts as a 'mixing agent' between copper and the other elements. Although several of the atom pairs in the gold containing alloy have positive enthalpies, thermodynamic considerations show that the high entropy contribution is sufficient to counterbalance

Zr-based conversion layer on Zn-Al-Mg alloy coated steel sheets: insights into the formation mechanism

International Nuclear Information System (INIS)

Lostak, Thomas; Maljusch, Artjom; Klink, Björn; Krebs, Stefan; Kimpel, Matthias; Flock, Jörg; Schulz, Stephan; Schuhmann, Wolfgang

2014-01-01

Zr-based conversion layers are considered as environmentally friendly alternatives replacing trication phosphatation in the automotive industry. Based on excellent electronic barrier properties they provide an effective corrosion protection of the metallic substrate. In this work, thin protective layers were grown on novel Zn-Al-Mg alloy coated steel sheets by increasing the local pH-value at the sample surface leading to deposition of a Zr-based conversion layer. For this purpose Zn-Al-Mg alloy (ZM) coated steel sheets were treated in an aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H 2 ZrF 6 ) and characterized after different immersion times with SKPFM and field emission SEM (FE-SEM)/EDX techniques. A deposition mechanism of Zr-based conversion coatings on microstructural heterogeneous Zn-Al-Mg alloy surfaces was proposed

Structural, electronic, magnetic and optical properties of Ni,Ti/Al-based Heusler alloys. A first-principles approach

Energy Technology Data Exchange (ETDEWEB)

Adebambo, Paul O. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; McPherson Univ., Abeokuta (Nigeria). Dept. of Physical and Computer Sciences; Adetunji, Bamidele I. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Bells Univ. of Technology, Oto (Nigeria). Dept. of Mathematics; Olowofela, Joseph A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Oguntuase, James A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Mathematics; Adebayo, Gboyega A. [Univ. of Agriculture. Abeokuta (Nigeria). Dept. of Physics; Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

2016-05-01

In this work, detailed first-principles calculations within the generalised gradient approximation (GGA) of electronic, structural, magnetic, and optical properties of Ni,Ti, and Al-based Heusler alloys are presented. The lattice parameter of C1{sub b} with space group F anti 43m (216) NiTiAl alloys is predicted and that of Ni{sub 2}TiAl is in close agreement with available results. The band dispersion along the high symmetry points W→L→Γ→X→W→K in Ni{sub 2}TiAl and NiTiAl Heusler alloys are also reported. NiTiAl alloy has a direct band gap of 1.60 eV at Γ point as a result of strong hybridization between the d state of the lower and higher valence of both the Ti and Ni atoms. The calculated real part of the dielectric function confirmed the band gap of 1.60 eV in NiTiAl alloys. The present calculations revealed the paramagnetic state of NiTiAl. From the band structure calculations, Ni{sub 2}TiAl with higher Fermi level exhibits metallic properties as in the case of both NiAl and Ni{sub 3}Al binary systems.

Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

Science.gov (United States)

Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

2016-01-01

The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles. PMID:28008967

FRACTIONAL RECRYSTALLIZATION KINETICS IN DIRECTLY COLD ROLLED Al-Mg, Al-Mg-Sc AND Al-Mg-Sc-Zr ALLOY

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M. S. Kaiser

2014-12-01

Full Text Available The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes

Preferential site occupancy of alloying elements in TiAl-based phases

Energy Technology Data Exchange (ETDEWEB)

Holec, David, E-mail: david.holec@unileoben.ac.at; Reddy, Rajeev K.; Klein, Thomas; Clemens, Helmut [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700 Leoben (Austria)

2016-05-28

First principles calculations are used to study the preferential occupation of ternary alloying additions into the binary Ti-Al phases, namely, γ-TiAl, α{sub 2}-Ti{sub 3}Al, β{sub o}-TiAl, and B19-TiAl. While the early transition metals (TMs, group IVB, VB, and VIB elements) prefer to substitute for Ti atoms in the γ-, α{sub 2}-, and B19-phases, they preferentially occupy Al sites in the β{sub o}-TiAl. Si is, in this context, an anomaly, as it prefers to sit on the Al sublattice for all four phases. B and C are shown to prefer octahedral Ti-rich interstitial positions instead of substitutional incorporation. The site preference energy is linked with the alloying-induced changes of energy of formation, hence alloying-related (de)stabilisation of the phases. We further show that the phase-stabilisation effect of early TMs on β{sub o}-phase has a different origin depending on their valency. Finally, an extensive comparison of our predictions with available theoretical and experimental data (which is, however, limited mostly to the γ-phase) shows a consistent picture.

Vacuum brazing of TiAl48Cr2Nb2 casting alloys based on TiAl (γ intermetallic compound

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Z. Mirski

2010-01-01

Full Text Available A growing interest in modern engineering materials characterised by increasingly better operational parameters combined with a necessity to obtain joints of such materials representing good operation properties create important research and technological problems of today. These issues include also titanium joints or joints of titanium alloys based on intermetallic compounds. Brazing is one of the basic and sometimes even the only available welding method used for joining the aforesaid materials in production of various systems, heat exchangers and, in case of titanium alloys based on intermetallic compounds, turbine elements and space shuttle plating etc. This article presents the basic physical and chemical properties as well as the brazability of alloys based on intermetallic compounds. The work also describes the principle and mechanisms of diffusion-brazed joint formation as well as reveals the results of metallographic and strength tests involving diffusion-welded joints of TiAl48Cr3Nb2 casting alloy based on TiAl (γ phase with the use of sandwich-type layers of silver-based parent metal (grade B- Ag72Cu-780 (AG 401 and copper (grade CF032A. Structural examination was performed by means of light microscopy, scanning electron microscope (SEM and energy dispersion spectrometer (EDS. Furthermore, the article reveals the results of shear strength tests involving the aforementioned joints.

Corrosion behaviors of Zn/Al-Mn alloy composite coatings deposited on magnesium alloy AZ31B (Mg-Al-Zn)

International Nuclear Information System (INIS)

Zhang Jifu; Zhang Wei; Yan Chuanwei; Du Keqin; Wang Fuhui

2009-01-01

After being pre-plated a zinc layer, an amorphous Al-Mn alloy coating was applied onto the surface of AZ31B magnesium alloy with a bath of molten salts. Then the corrosion performance of the coated magnesium alloy was examined in 3.5% NaCl solution by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the single Zn layer was active in the test solution with a high corrosion rate while the Al-Mn alloy coating could effectively protect AZ31B magnesium alloy from corrosion in the solution. The high corrosion resistance of Al-Mn alloy coating was ascribed to an intact and stable passive film formed on the coating. The performances of the passive film on Al-Mn alloy were further investigated by Mott-Schottky curve and X-ray photoelectron spectroscopy (XPS) analysis. It was confirmed that the passive film exhibited n-type semiconducting behavior in 3.5% NaCl solution with a carrier density two orders of magnitude less than that formed on pure aluminum electrode. The XPS analysis indicated that the passive film was mainly composed of AlO(OH) after immersion for long time and the content of Mn was negligible in the outer part of the passive film. Based on the EIS measurement, electronic structure and composition analysis of the passive film, a double-layer structure, with a compact inner oxide and a porous outer layer, of the film was proposed for understanding the corrosion process of passive film, with which the experimental observations might be satisfactorily interpreted.

High-temperature deformation behavior and mechanical properties of rapidly solidified Al-Li-Co and Al-Li-Zr alloys

International Nuclear Information System (INIS)

Sastry, S.M.L.; Oneal, J.E.

1984-01-01

The deformation behavior at 25-300 C of rapidly solidified Al-3Li-0.6Co and Al-3Li-0.3Zr alloys was studied by tensile property measurements and transmission electron microscopic examination of dislocation substructures. In binary Al-3Li and Al-3Li-Co alloys, the modulus normalized yield stress increases with an increase in temperature up to 150 C and then decreases. The yield stress at 25 C of Al-3Li-0.3Zr alloys is 180-200 MPa higher than that of Al-3Li alloys. However, the yield stress of the Zr-containing alloy decreases drastically with increasing temperatures above 75 C. The short-term yield stresses at 100-200 C of the Al-3Li-based alloys are higher than that of the conventional high-temperature Al alloys. The temperature dependences of the flow stresses of the alloys were analyzed in terms of the magnitudes and temperature dependences of the various strengthening contributions in the two alloys. The dislocation substructures at 25-300 C were correlated with mechanical properties. 19 references

Particle Based Alloying by Accumulative Roll Bonding in the System Al-Cu

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Mathias Göken

2011-11-01

Full Text Available The formation of alloys by particle reinforcement during accumulative roll bonding (ARB, and subsequent annealing, is introduced on the basis of the binary alloy system Al-Cu, where strength and electrical conductivity are examined in different microstructural states. An ultimate tensile strength (UTS of 430 MPa for Al with 1.4 vol.% Cu was reached after three ARB cycles, which almost equals UTS of the commercially available Al-Cu alloy AA2017A with a similar copper content. Regarding electrical conductivity, the UFG structure had no significant influence. Alloying of aluminum with copper leads to a linear decrease in conductivity of 0.78 µΩ∙cm/at.% following the Nordheim rule. On the copper-rich side, alloying with aluminum leads to a slight strengthening, but drastically reduces conductivity. A linear decrease of electrical conductivity of 1.19 µΩ∙cm/at.% was obtained.

The quasicrystalline phase formation in Al-Cu-Cr alloys produced by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Sviridova, T.A.; Shevchukov, A.P.; Shelekhov, E.V. [National University of Science and Technology ' MISIS' , Moscow 119049 (Russian Federation); Diakonov, D.L. [Bardin Central Research Institute for the Iron and Steel Industry, Moscow 105005 (Russian Federation); Tcherdyntsev, V.V.; Kaloshkin, S.D. [National University of Science and Technology ' MISIS' , Moscow 119049 (Russian Federation)

2011-06-15

Research highlights: > Formation of decagonal quasicrystalline phase in Al-Cu-Cr alloys. > Obtained decagonal phase belongs to D{sub 3} family of decagonal quasicrystals. > Decagonal phase has 1.26 nm periodicity along 10-fold axis. > Alloys were produced by combination of mechanical alloying and subsequent annealing. > Phase composition of as-milled powders depending on annealing temperature. - Abstract: Almost single-phase decagonal quasicrystal with periodicity of 1.26 nm along 10-fold axis was produced in Al{sub 69}Cu{sub 21}Cr{sub 10} and Al{sub 72.5}Cu{sub 16.5}Cr{sub 11} alloys using combination of mechanical alloying (MA) and subsequent annealing. Phase transformations of as-milled powders depending on annealing temperature in the range of 200-800 deg. C are examined. Since the transformations can be explained based on kinetic and thermodynamic reasons it seems that applied technique (short preliminary MA followed by the annealing) permits to produce the equilibrium phases rather than metastable ones.

Effect of Al and Y2O3 on Mechanical Properties in Mechanically Alloyed Nanograin Ni-Based Alloys.

Science.gov (United States)

Kim, Chung Seok; Kim, Il-Ho

2015-08-01

The effects of aluminum and Y2O3 on the mechanical properties in nano grain Ni-based alloys have been investigated. The test specimens are prepared by mechanical alloying at an Ar atmosphere. The addition of Y2O3 and Al may cause an increase in the tensile strength at room temperature, 400 °C and 600 °C. However, it was confirmed that the increase of tensile strength at room temperature and 400 °C was predominantly caused by addition of Y2O3, while that at 600 °C was mainly due to addition of Al. These results can be attributed to the dispersion strengthening of Y2O3, preventing the formation of Cr2O3 and the change of fracture mode at 600 °C by the addition of Al.

Application of mechanical alloying to synthesis of intermetallic phases based alloys

International Nuclear Information System (INIS)

Dymek, S.

2001-01-01

Mechanical alloying is the process of synthesis of powder materials during milling in high energetic mills, usually ball mills. The central event in mechanical alloying is the ball-powder-ball collision. Powder particles are trapped between the colliding balls during milling and undergo deformation and/or fracture. Fractured parts are cold welded. The continued fracture and cold welding results in a uniform size and chemical composition of powder particles. The main applications of mechanical alloying are: processing of ODS alloys, syntheses of intermetallic phases, synthesis of nonequilibrium structures (amorphous alloys, extended solid solutions, nanocrystalline, quasi crystals) and magnetic materials. The present paper deals with application of mechanical alloying to synthesis Ni A l base intermetallic phases as well as phases from the Nb-Al binary system. The alloy were processed from elemental powders. The course of milling was monitored by scanning electron microscopy and X-ray diffraction. After milling, the collected powders were sieved by 45 μm grid and hot pressed (Nb alloys and NiAl) or hot extruded (NiAl). The resulting material was fully dense and exhibited fine grain (< 1 μm) and uniform distribution of oxide dispersoid. The consolidated material was compression and creep tested. The mechanical properties of mechanically alloys were superior to properties of their cast counterparts both in the room and elevated temperatures. Higher strength of mechanically alloyed materials results from their fine grains and from the presence of dispersoid. At elevated temperatures, the Nb-Al alloys have higher compression strength than NiAl-based alloys processed at the same conditions. The minimum creep rates of mechanically alloyed Nb alloys are an order of magnitude lower than analogously processed NiAl-base alloys. (author)

Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

Science.gov (United States)

Klein, Thomas; Clemens, Helmut; Mayer, Svea

2016-01-01

Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT) offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys. PMID:28773880

Mechanical properties of Fe3Al-based alloys with addition of carbon, niobium and titanium

International Nuclear Information System (INIS)

Zhang Zhengrong; Liu Wenxi

2006-01-01

Several Fe 3 Al-based iron aluminides with the addition of alloying elements carbon, niobium and titanium were produced by vacuum induction melting (VIM) and hot spinning forging. Analytic techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used in studying the microstructure and fracture manner of these alloys. The results show that due to the addition of alloying elements, the superlattice dislocations tend towards multiple slipping, leaving behind on their slip plane ribbons of square-shaped slip-induced antiphase boundaries. The elongation of Fe 3 Al in tension at room temperature increased to about 10% by the addition of suitable alloying elements, the usage of thermo-mechanical processing that has the function of refining grains and substructures, and subsequent annealing

Synthesis Of NiCrAlC alloys by mechanical alloying

International Nuclear Information System (INIS)

Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M.

2010-01-01

The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni 3 Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

International Nuclear Information System (INIS)

Andoh, A.

1997-01-01

The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

The electrochemical properties of melt-spun Al-Si-Cu alloys

International Nuclear Information System (INIS)

Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing; Sun Zhanbo; Song Xiaoping; Yang Sen; Wang Liqun

2011-01-01

Highlights: → Non-equilibrium Al 75-X Si 25 Cu X alloys exhibit high lithiation storages. → The lithiation mechanism is different from melt-spun Al-Si-Mn system. → The structural evolution is mitigated in the non-equilibrium alloys. → Volume variation is alleviated due to the co-existence of Al 2 Cu, α-Si and α-Al. - Abstract: Melt spinning was used to prepare Al 75-X Si 25 Cu X (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, α-Si and Al 2 Cu co-existed in the alloys. Nano-scaled α-Al grains, as the matrix, formed in the as-quenched ribbons. The Al 74 Si 25 Cu 1 and Al 71 Si 25 Cu 4 anodes exhibited initial discharge specific capacities of 1539 mAh g -1 , 1324 mAh g -1 and reversible capacities above 472 mAh g -1 , 508 mAh g -1 at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled α-Al, α-Si, and Al 2 Cu for the present alloys.

Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

International Nuclear Information System (INIS)

Liang, S M; Schmid-Fetzer, R

2016-01-01

The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented. (paper)

Influence of Processing on the Microstructure and Mechanical Properties of a NbAl3-Base Alloy

Science.gov (United States)

Hebsur, Mohan G.; Locci, Ivan E.; Raj, S. V.; Nathal, Michael V.

1992-01-01

Induction melting and rapid solidification processing, followed by grinding to 75-micron powder and P/M consolidation, have been used to produce a multiphase, NbAl3-based, oxidation-resistant alloy of Nb-67Al-7Cr-0.5Y-0.25W composition whose strength and ductility are significantly higher than those of the induction-melted alloy at test temperatures of up to 1200 K. Attention is given to the beneficial role of microstructural refinement; the major second phase, AlNbCr, improves both oxidation resistance and mechanical properties.

Recent advances in alloy design of Ni{sub 3}Al alloys for structural use

Energy Technology Data Exchange (ETDEWEB)

Liu, C.T.; George, E.P.

1996-12-31

This is a comprehensive review of recent advances in R&D of Ni{sub 3}Al-based alloys for structural use at elevated temperatures in hostile environments. Recent studies indicate that polycrystalline Ni{sub 3}Al is intrinsically quite ductile at ambient temperatures, and its poor tensile ductility and brittle grain-boundary fracture are caused mainly by moisture-induced hydrogen embrittlement when the aluminide is tested in moisture- or hydrogen-containing environments. Tensile ductility is improved by alloying with substitutional and interstitial elements. Among these additives, B is most effective in suppressing environmental embrittlement and enhancing grain-boundary cohesion, resulting in a dramatic increase of tensile ductility at room temperature. Both B-doped and B-free Ni{sub 3}Al alloys exhibit brittle intergranular fracture and low ductility at intermediate temperatures (300-850 C) because of oxygen-induced embrittlement in oxidizing environments. Cr is found to be most effective in alleviating elevated-temperature embrittlement. Parallel efforts on alloy development using physical metallurgy principles have led to development of several Ni{sub 3}Al alloys for industrial use. The unique properties of these alloys are briefly discussed. 56 refs, 15 figs, 3 tabs.

Theoretical prediction of the electronic transport properties of the Al-Cu alloys based on the first-principle calculation and Boltzmann transport equation

Science.gov (United States)

Choi, Garam; Lee, Won Bo

Metal alloys, especially Al-based, are commonly-used materials for various industrial applications. In this paper, the Al-Cu alloys with varying the Al-Cu ratio were investigated based on the first-principle calculation using density functional theory. And the electronic transport properties of the Al-Cu alloys were carried out using Boltzmann transport theory. From the results, the transport properties decrease with Cu-containing ratio at the temperature from moderate to high, but with non-linearity. It is inferred by various scattering effects from the calculation results with relaxation time approximation. For the Al-Cu alloy system, where it is hard to find the reliable experimental data for various alloys, it supports understanding and expectation for the thermal electrical properties from the theoretical prediction. Theoretical and computational soft matters laboratory.

Structural high-temperature and (βNiAl+γ)-alloys based on Ni-Al-Co-Me systems with an improved low-temperature ductility

International Nuclear Information System (INIS)

Povarova, K.B.; Kazanskaya, N.K.; Drozdov, A.A.; Lomberg, B.S.; Gerasimov, V.V.

2001-01-01

The βNiAl-based alloys (B2) have lower density higher resistance to oxidation, and higher melting temperature relative to those of Ni-superalloys or γ'Ni 3 Al-base alloys. An improved low-temperature ductility of advanced Ni-AI-Co-M β+γ alloys(El=9-16 % at 293-1173 K is achieved due to the formation γ-Ni solid solution intergranular interlayers of eutectic origin. Secondary γ and/or γ' precipitates form in the grains of the supersaturated β-solid solution upon heat treatment at 1473-1573 K and 1073-1173 K. The limiting contents of alloying elements (Ti, Hf, Nb, Ta, Cr, Mo) for the (β+γ) alloys Ni - (19-29) % AI - (22-35) % Co, are determined which allowed to avoid the formation of primary γ'-phase (decrease solidus temperature ≤1643 K) and hard phases of the types σ, η and δ (decrease ductility). Alloying affects the morphology of the secondary γ and γ' precipitates: globular equiaxed precipitates are formed in the alloys containing Cr, Mo, and needle precipitates are formed in alloys alloys containing γ'-forming elements Nb, Ta and, especially, Ti and Hf. After directional solidification, (β+γ')-alloys have directed columnar special structure with a low extension of transverse grain boundaries. This microstructure allows one to increase UTS, by a factor 1,5-2 and long-term strength (time to rupture increase by a factor of 5-10 at 1173 K). (author)

Effects of Al-Mn-Ti-P-Cu master alloy on microstructure and properties of Al-25Si alloy

Directory of Open Access Journals (Sweden)

Xu Chunxiang

2013-09-01

Full Text Available To obtain a higher microstructural refining efficiency, and improve the properties and processing ability of hypereutectic Al-25Si alloy, a new environmentally friendly Al-20.6Mn-12Ti-0.9P-6.1Cu (by wt.% master alloy was fabricated; and its modification and strengthening mechanisms on the Al-25Si alloy were studied. The mechanical properties of the unmodified, modified and heat treated alloys were investigated. Results show that the optimal addition amount of the Al-20.6Mn-12Ti-0.9P-6.1Cu master alloy is 4wt.%. In this case, primary Si and eutectic Si as well as メ-Al phase were clearly refined, and this refining effect shows an excellent long residual action as it can be heat-retained for at least 5 h. After being T6 heat treated, the morphology of primary and eutectic Si in the Al-25Si alloys with the addition of 4wt.% Al-20.6Mn-12Ti-0.9P-6.1Cu alloy changes into particles and short rods. The average grain size of the primary and eutectic Si decreases from 250 レm (unmodified to 13.83 レm and 35 レm (unmodified to 7 レm; the メ-Al becomes obviously finer and the distribution of Si phases tends to be uniform and dispersed. Meanwhile, the tensile properties are improved obviously; the tensile strengths at room temperature and 300 ìC reach 241 MPa and 127 MPa, increased by 153.7% and 67.1%, respectively. In addition, the tensile fracture mechanism changes from brittle fracture for the alloy without modification to ductile fracture after modification. Modifying the morphology of Si phase and strengthening the matrix can effectively block the initiation and propagation of cracks, thus improving the strength of the hypereutectic Al-25Si alloy.

Viscosity of Industrially Important Zn-Al Alloys Part II: Alloys with Higher Contents of Al and Si

Science.gov (United States)

Nunes, V. M. B.; Queirós, C. S. G. P.; Lourenço, M. J. V.; Santos, F. J. V.; Nieto de Castro, C. A.

2018-05-01

The viscosity of Zn-Al alloys melts, with industrial interest, was measured for temperatures between 693 K and 915 K, with an oscillating cup viscometer, and estimated expanded uncertainties between 3 and 5 %, depending on the alloy. The influence of minor components, such as Si, Mg and Ce + La, on the viscosity of the alloys is discussed. An increase in the amount of Mg triggers complex melt/solidification processes while the addition of Ce and La renders alloys viscosity almost temperature independent. Furthermore, increases in Al and Si contents decrease melts viscosity and lead to an Arrhenius type behavior. This paper complements a previous study describing the viscosity of Zn-Al alloys with quasi-eutectic compositions.

The electrochemical properties of melt-spun Al-Si-Cu alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang Linping; Wang Fei; Liang Pu; Song Xianlei; Hu Qing [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Sun Zhanbo, E-mail: szb@mail.xjtu.edu.cn [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Song Xiaoping; Yang Sen; Wang Liqun [MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

2011-10-03

Highlights: {yields} Non-equilibrium Al{sub 75-X}Si{sub 25}Cu{sub X} alloys exhibit high lithiation storages. {yields} The lithiation mechanism is different from melt-spun Al-Si-Mn system. {yields} The structural evolution is mitigated in the non-equilibrium alloys. {yields} Volume variation is alleviated due to the co-existence of Al{sub 2}Cu, {alpha}-Si and {alpha}-Al. - Abstract: Melt spinning was used to prepare Al{sub 75-X}Si{sub 25}Cu{sub X} (X = 1, 4, 7, 10 mol%) alloy anode materials for lithium-ion batteries. A metastable supersaturated solid solution of Si and Cu in fcc-Al, {alpha}-Si and Al{sub 2}Cu co-existed in the alloys. Nano-scaled {alpha}-Al grains, as the matrix, formed in the as-quenched ribbons. The Al{sub 74}Si{sub 25}Cu{sub 1} and Al{sub 71}Si{sub 25}Cu{sub 4} anodes exhibited initial discharge specific capacities of 1539 mAh g{sup -1}, 1324 mAh g{sup -1} and reversible capacities above 472 mAh g{sup -1}, 508 mAh g{sup -1} at the 20th cycle, respectively. The specific capacities reduced as the increase of the Cu content. AlLi intermetallic compound was detected in the lithiated alloys. It is concluded that the lithiation mechanism of the Al-Si-based alloys can be affected by the third component. The structural evolution and volume variation can be mitigated due to the formation of non-equilibrium state and the co-existence of nano-scaled {alpha}-Al, {alpha}-Si, and Al{sub 2}Cu for the present alloys.

Interdiffusion between U-Mo alloys and Al or Al alloys at 340 deg. C. Irradiation plan

International Nuclear Information System (INIS)

Fortis, A.M.; Mirandou, M.; Ortiz, M.; Balart, S.; Denis, A.; Moglioni, A.; Cabot, P.

2005-01-01

Out of reactor interdiffusion experiments between U-Mo alloys and Al alloys made close to fuel operation temperature are needed to validate the results obtained above 500 deg. C. A study of interdiffusion between U-Mo and Al or Al alloys, out and in reactor, has been initiated. The objective is to characterize the interdiffusion layer around 250 deg. C and study the influence of neutron irradiation. Irradiation experiments will be performed in the Argentine RA3 reactor and chemical diffusion couples will be fabricated by Friction Stir Welding (FSW) technique. In this work out-of-pile diffusion experiments performed at 340 deg. C are presented. Friction Stir Welding (FSW) was used to fabricate some of the samples. One of the results is the presence of Si, in the interaction layer, coming from the Al alloy. This is promising in the sense that the absence of Al rich phases may also be expected at low temperature. (author)

The Evaluation of the Corrosion Resistance of the Al-Si Alloys Antimony Alloyed

Directory of Open Access Journals (Sweden)

Svobodova J.

2014-06-01

Full Text Available This paper deals with the evaluation of the corrosion resistance of the Al-Si alloys alloyed with the different amount of antimony. Specifically it goes about the alloy AlSi7Mg0,3 which is antimony alloyed in the concentrations 0; 0,001; 0,005; 0,01 a 0,05 wt. % of antimony. The introduction of the paper is dedicated to the theory of the aluminium alloys corrosion resistance, testing and evaluation of the corrosion resistance. The influence of the antimony to the Al-Si alloys properties is described further in the introduction. The experimental part describes the experimental samples which were prepared for the experiment and further they were exposed to the loading in the atmospheric conditions for a period of the 3 months. The experimental samples were evaluated macroscopically and microscopically. The results of the experiment were documented and the conclusions in terms of the antimony impact to the corrosion resistance of the Al-Si alloy were concluded. There was compared the corrosion resistance of the Al-Si alloy antimony alloyed (with the different antimony content with the results of the Al-Si alloy without the alloying after the corrosion load in the atmospheric conditions in the experiment.

Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Thompson, Zachary T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-10-01

Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.

The dissimilar brazing of Kovar alloy to SiCp/Al composites using silver-based filler metal foil

Science.gov (United States)

Wang, Peng; Xu, Dongxia; Zhai, Yahong; Niu, Jitai

2017-09-01

Aluminum metal matrix composites with high SiC content (60 vol.% SiCp/Al MMCs) were surface metallized with a Ni-P alloy coating, and vacuum brazing between the composites and Kovar alloy were performed using rapidly cooled Ag-22.0Cu-15.9In-10.86Sn-1.84Ti (wt%) foil. The effects of Ni-P alloy coating and brazing parameters on the joint microstructures and properties were researched by SEM, EDS, and single lap shear test, respectively. Results show that Ag-Al intermetallic strips were formed in the 6063Al matrix and filler metal layer because of diffusion, and they were arranged regularly and accumulated gradually as the brazing temperature was increased ( T/°C = 550-600) or the soaking time was prolonged ( t/min = 10-50). However, excessive strips would destroy the uniformity of seams and lead to a reduced bonding strength (at most 70 MPa). Using a Ni-P alloy coating, void free joints without those strips were obtained at 560 °C after 20 min soaking time, and a higher shear strength of 90 MPa was achieved. The appropriate interface reaction ( 2 μm transition layer) that occurred along the Ni-P alloy coating/filler metal/Kovar alloy interfaces resulted in better metallurgical bonding. In this research, the developed Ag-based filler metal was suitable for brazing the dissimilar materials of Ni-P alloy-coated SiCp/Al MMCs and Kovar alloy, and capable welding parameters were also broadened.

Composites Strengthened with Graphene Platelets and Formed in Semisolid State Based on α and α/β MgLiAl Alloys

Science.gov (United States)

Dutkiewicz, Jan; Rogal, Łukasz; Fima, Przemyslaw; Ozga, Piotr

2018-05-01

MgLiAl base composites strengthened with graphene platelets were prepared by semisolid processing of ball-milled alloy chips with 2% of graphene platelets. Composites strengthened with graphene platelets show higher hardness and yield stress than the cast alloys, i.e., 160 MPa as compared to 90 MPa for as-cast alloy MgLi9Al1.5. Mechanical properties for MgLiAl-based composites were similar or higher than for composites based on conventional AZ91 or WE43 alloys. The strengthening however was not only due to the presence of graphene, but also phases resulting from the reaction between carbon and lithium, i.e., Li2C2 carbide. Graphene platelets were located at globules boundaries resulting from semisolid processing for all investigated composites. Graphene platelets were in agglomerates forming continuous layers at grain boundaries in the composite based on the alloy MgLi4.5Al1.5. The shape of agglomerates was more complex and wavy in the composite based on MgLi9Al1.5 alloy most probably due to lithium-graphene reaction. Electron diffraction from the two-phase region α + β in MgLi9Al1.5 indicated that [001]α and [110]β directions are rotated about 4° from the ideal relationship [001] hex || [110] bcc phases. It showed higher lattice rotation than in earlier studies what is most probably caused by lattice slip and rotation during semisolid pressing causing substantial deformation particularly within the β phase. Raman spectroscopy studies confirmed the presence of graphene platelets within agglomerates and in addition the presence mainly of Li2C2 carbides in composites based on MgLi4.5Al1.5 and Mg9Li1.5Al alloys. From the character of Raman spectra refinement of graphene platelets was found in comparison with their initial size. The graphene areas without carbides contain graphene nanoplatelets with lateral dimension close to initial graphene sample. Electron diffraction allowed to confirm the presence of Li2C2 carbide at the surface of agglomerates found from

High Temperature Deformation of Twin-Roll Cast Al-Mn-Based Alloys after Equal Channel Angular Pressing.

Science.gov (United States)

Málek, Přemysl; Šlapáková Poková, Michaela; Cieslar, Miroslav

2015-11-12

Twin roll cast Al-Mn- and Al-Mn-Zr-based alloys were subjected to four passes of equal channel angular pressing. The resulting grain size of 400 nm contributes to a significant strengthening at room temperature. This microstructure is not fully stable at elevated temperatures and recrystallization and vast grain growth occur at temperatures between 350 and 450 °C. The onset of these microstructure changes depends on chemical and phase composition. Better stability is observed in the Al-Mn-Zr-based alloy. High temperature tensile tests reveal that equal channel angular pressing results in a softening of all studied materials at high temperatures. This can be explained by an active role of grain boundaries in the deformation process. The maximum values of ductility and strain rate sensitivity parameter m found in the Al-Mn-Zr-based alloy are below the bottom limit of superplasticity (155%, m = 0.25). However, some features typical for superplastic behavior were observed-the strain rate dependence of the parameter m , the strengthening with increasing grain size, and the fracture by diffuse necking. Grain boundary sliding is believed to contribute partially to the overall strain in specimens where the grain size remained in the microcrystalline range.

Reactive wetting of Ti-6Al-4V alloy by molten Al 4043 and 6061 alloys at 600-700 C

Energy Technology Data Exchange (ETDEWEB)

Lin, Qiaoli; Li, Fuxiang; Jin, Peng; Yu, Weiyuan [Lanzhou Univ. of Technology (China). State Key Lab. of Advanced Processing and Recycling of Non-ferrous Metal

2017-06-15

Wetting of Ti-6Al-4V alloy by two industrial grade Al alloys (i.e., Al 6061 and 4043 alloys) was studied using the sessile drop method at 600-700 C under high vacuum. Al/Ti-6Al-4V is a typical reactive wetting system with good final wettability accompanied by the formation of precursor film which is actually an extended reaction layer. The formation mechanism for the precursor film is ''subcutaneous infiltration''. The small amount of alloying element Si in the alloys can cause significant segregation at the liquid/solid interface which satisfies the thermodynamic condition. The wetting behavior can be described by the classic reaction product control models, and Ti{sub 7}Al{sub 5}Si{sub 12} decomposition and Al{sub 3}Ti formation correspond to the two spreading stages. The small difference in alloying elements in Al 6061 and 4043 resulted in distinctly different interface structures, formation of precursor film and spreading dynamics, especially for the Si segregation at the interface.

Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

Energy Technology Data Exchange (ETDEWEB)

Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-09-18

FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO₂ or ZrO₂. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

The Effect of Grain-refinement on Zn-10Al Alloy Damping Properties

Directory of Open Access Journals (Sweden)

Piwowarski G.

2014-12-01

Full Text Available The paper is devoted to grain-refinement of the medium-aluminium zinc based alloys (MAl-Zn. The system examined was sand cast Zn- 10 wt. %. Al binary alloy (Zn-10Al doped with commercial Al-3 wt. % Ti - 0.15 wt. % C grain refiner (Al-3Ti-0.15C GR. Basing on the measured attenuation coefficient of ultrasonic wave it was stated that together with significantly increased structure fineness damping decreases only by about 10 - 20%. The following examinations should establish the influence of the mentioned grain-refinement on strength and ductility of MAl-Zn cast alloys.

Ni3Al intermetallide-based alloy: a promising material for turbine blades

International Nuclear Information System (INIS)

Kablov, E.N.; Lomberg, B.S.; Buntushkin, V.P.; Golubovskij, E.R.; Muboyadzhyan, S.A.

2002-01-01

A consideration is given to properties and structure of a cast intermetallic alloy grade VKNA-4U-mono- with monocrystalline structure in the temperature range of 20-1250 deg C. The influence of long-term heating at 1200 deg C on the stability of alloy mechanical properties is investigated. The advantages of a cast alloy on the basis of alloyed intermetallic compound Ni 3 Al are demonstrated, the processing and physical properties of the alloy are presented [ru

Creep behavior of Ti3Al-Nb intermetallic alloys

International Nuclear Information System (INIS)

Yu, T.H.; Yue, W.J.; Koo, C.H.

1997-01-01

It is well known that Ti 3 Al-Nb alloys are potential materials for aerospace applications. The creep property is an important consideration when materials are used at high temperature. In this article, the effect of microstructure of Ti-25Al-10Nb alloy on the creep property was investigated, and the creep property of Ti-25Al-10Nb alloy modified by small addition of silicon 0.2 at.% or carbon 0.1 at.% was observed. The alloy with the addition of molybdenum to replace part of niobium 2 at.% was also studied. The experimental results show that the furnace-cooled Ti-25Al-10Nb alloy has superior creep resistance to the air-cooled Ti-25Al-10Nb alloy at 200 MPa, but exhibits poor creep resistance at 250 MPa or above. Small addition of silicon to the Ti-25Al-10Nb alloy may increase creep resistance. Small addition of carbon to the Ti-25Al-10Nb alloy may reduce creep resistance but raise rupture strain. Molybdenum is the most effective alloying element to increase creep resistance for the Ti-25Al-10Nb alloy. The creep mechanism of Ti-25Al-10Nb alloy is governed by dislocation climb. (orig.)

Ultra-precision machining induced phase decomposition at surface of Zn-Al based alloy

International Nuclear Information System (INIS)

To, S.; Zhu, Y.H.; Lee, W.B.

2006-01-01

The microstructural changes and phase transformation of an ultra-precision machined Zn-Al based alloy were examined using X-ray diffraction and back-scattered electron microscopy techniques. Decomposition of the Zn-rich η phase and the related changes in crystal orientation was detected at the surface of the ultra-precision machined alloy specimen. The effects of the machining parameters, such as cutting speed and depth of cut, on the phase decomposition were discussed in comparison with the tensile and rolling induced microstrucutural changes and phase decomposition

The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

Science.gov (United States)

Gilman, P. S.

1984-01-01

Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

Effect of Al-5Ti-0.62C-0.2Ce Master Alloy on the Microstructure and Tensile Properties of Commercial Pure Al and Hypoeutectic Al-8Si Alloy

Directory of Open Access Journals (Sweden)

Wanwu Ding

2017-06-01

Full Text Available Al-5Ti-0.62C-0.2Ce master alloy was synthesized by a method of thermal explosion reaction in pure molten aluminum and used to modify commercial pure Al and hypoeutectic Al-8Si alloy. The microstructure and tensile properties of commercial pure Al and hypoeutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min can significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min still has a good refinement effect. The tensile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min can significantly refine both α-Al grains and eutectic Si of hypoeutectic Al-8Si alloy. The dendritic α-Al grains were significantly refined to tiny equiaxed grains. The morphology of the eutectic Si crystals was significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like eutectic Si. The tensile strength and elongation of hypoeutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.

Design and properties of advanced {gamma}(TiAl) alloys

Energy Technology Data Exchange (ETDEWEB)

Appel, F; Clemens, H; Oehring, M [Institute for Materials Research, GKSS Research Centre, Max-Planck-Strasse, D-21502 Geesthacht (Germany)

2001-07-01

Intermetallic titanium aluminides are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. Some of these concerns are addressed in the present paper through global commentary on the physical metallurgy and technology of gamma TiAl-base alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high-temperature capability. (author)

Design and properties of advanced γ(TiAl) alloys

International Nuclear Information System (INIS)

Appel, F.; Clemens, H.; Oehring, M.

2001-01-01

Intermetallic titanium aluminides are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. Some of these concerns are addressed in the present paper through global commentary on the physical metallurgy and technology of gamma TiAl-base alloys. Particular emphasis is paid on recent developments of TiAl alloys with enhanced high-temperature capability. (author)

Corrosion Inhibition Study of Al-Cu-Ni Alloy in Simulated Sea-Water ...

African Journals Online (AJOL)

Akorede

ABSTRACT: A study on the inhibition of Al-Cu-Ni alloy in simulated ... which the percentage of Copper, and Nickel were kept .... proceed based on equation of reaction in eqn (4). Al .... Sodium-Modified A356.0-Type Al-Si-Mg Alloy in Simulated.

Development of medical guide wire of Cu-Al-Mn-base superelastic alloy with functionally graded characteristics.

Science.gov (United States)

Sutou, Yuji; Omori, Toshihiro; Furukawa, Akihisa; Takahashi, Yukinori; Kainuma, Ryosuke; Yamauchi, Kiyoshi; Yamashita, Shuzo; Ishida, Kiyohito

2004-04-15

A new type of medical guide wire with functionally graded hardness from the tip to the end was developed with the use of Cu-Al-Mn-based alloys. The superelasticity (SE) of the Cu-Al-Mn-based alloys in the tip is drastically improved by controlling the grain size, whereas the end of the wire is hardened using bainitic transformation by aging at around 200-400 degrees C. Therefore, the tip of the guide wire shows a superelasticity and its end has high stiffness. This guide wire with functionally graded characteristics shows excellent pushability and torquability, superior to that of the Ni-Ti guide wire. Copyright 2004 Wiley Periodicals, Inc.

Density of liquid NiCoAlCr quarternary alloys measured by modified sessile drop method

Institute of Scientific and Technical Information of China (English)

FANG Liang; ZHANG Shu-fang; XIAO Feng; YANG Ling-chuan; DONG Jian-xin; CAO Chun-lan; TAO Zai-nan; K. MUKAI

2006-01-01

The densities of liquid NiCoAlCr quaternary alloys with a fixed molar ratio of Ni to Co to Al (x(Ni)-x(Co)-x(Al)≈73-12-15) which is close to the average value of the commercial Ni-based superalloys TMS75, INCO713, CM247LC and CMSX-4, and the mass fraction of chromium changes from 0 to 9% were measured by a modified sessile drop method. It is found that with increasing temperature and chromium concentration in the alloys, the densities of the liquid NiCoAlCr quaternary alloys decrease, whereas the molar volume of the liquid NiCoAlCr quaternary alloys increases. And the liquid densities of NiCoAlCr quaternary alloys calculated from the partial molar volumes of nickel, cobalt, aluminum and chromium in the corresponding Ni-bases binary alloys are in good agreement with the experimental ones, i.e. within the error tolerance range the densities of the liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. The molar volume of liquid NiCoAlCr binary alloy shows a negative deviation from the ideal linear mixing and the deviation changes small with the increase of chromium concentration at the same temperature.

Creep resistance in a new alloy based on Fe3Al

International Nuclear Information System (INIS)

Morris, D.G.

1994-01-01

Iron aluminide alloys based on the composition Fe 3 Al are receiving considerable attention as structural materials for applications at high temperatures in view of their excellent resistance to oxidation and corrosion as well as reasonable mechanical properties. Recently, problems associated with poor ductility at room temperature have been alleviated by small additions of Cr and by microstructure control, as well by as the realization that the low ductility is, in part, extrinsic behavior due to environmental attack. These materials suffer also from a loss of their good strength at temperatures above about 600 C, and recent attention has led also to the development of creep resistant alloys. The present report considers a new alloy developed for improved creep resistance which shows also good oxidation and erosion resistance. Effort has been devoted to an examination of the dislocation structures that characterize deformation, both cold and hot, during fast tensile straining as well as during creep testing

Microstructure and properties of thermally sprayed Al-Sn-based alloys for plain bearing applications

Science.gov (United States)

Marrocco, T.; Driver, L. C.; Harris, S. J.; McCartney, D. G.

2006-12-01

Al-Sn plain bearings for automotive applications traditionally comprise a multilayer structure. Conventionally, bearing manufacturing involves casting the Al-Sn alloy and roll-bonding to a steel backing strip. Recently, high-velocity oxyfuel (HVOF) thermal spraying has been used as a novel alternative manufacturing route. The present project extends previous work on ternary Al-Sn-Cu alloys to quaternary systems, which contain specific additions for potentially enhanced properties. Two alloys were studied in detail, namely, Al-20wt.%Sn-1wt.%Cu-2wt.%Ni and Al-20wt.%Sn-1wt.%Cu-7wt.%Si. This article will describe the microstructural evolution of these alloys following HVOF spraying onto steel substrates and subsequent heat treatment. The microstructures of powders and coatings were investigated by scanning electron microscopy, and the phases were identified by x-ray diffraction. Coating microhardnesses were determined under both as-sprayed and heat-treated conditions, and by the differences related to the microstructures that developed. Finally, the wear behavior of the sprayed and heat-treated coatings in hot engine oil was measured using an industry standard test and was compared with that of previous work on a ternary alloy.

The shock Hugoniot of the intermetallic alloy Ti-46.5Al-2Nb-2Cr

International Nuclear Information System (INIS)

Millett, Jeremy; Gray, George T. Rusty III; Bourne, Neil

2000-01-01

Plate impact experiments were conducted on a γ-titanium aluminide (TiAl) based ordered intermetallic alloy. Stress measurements were recorded using manganin stress gauges supported on the back of TiAl targets using polymethylmethacrylate windows. The Hugoniot in stress-particle velocity space for this TiAl alloy was deduced using impedance matching techniques. The results in this study are compared to the known Hugoniot data of the common alpha-beta engineering Ti-based alloy Ti-6Al-4V. The results of the current study on the intermetallic alloy TiAl support that TiAl possesses a significantly higher stress for a given particle velocity than the two-phase Ti-6Al-4V alloy. (c) 2000 American Institute of Physics

Study on Microstructure and Mechanical Properties of Al-Li Based Alloys Processed by Extrusion.

Science.gov (United States)

Kim, Yong-Ho; Yoo, Hyo-Sang; Jung, Chang-Gi; Son, Hyeon-Taek

2018-03-01

Aluminum and its alloys, due to their low density, high specific strength and high corrosion resistance amongst various structural materials, are used in a wide range of industrial applications for different aqueous solutions. In the present study, we studied effects of Ce addition on microstructure and mechanical properties of Al-2Li-1Cu-0.8Mg-0.1Zr alloys. The melt was held at 780 °C for 20 min and poured into a mold. And as-cast Al alloys were hot-extruded into a plate that was 4 mm in thickness with a reduction ratio of 14:1. The extruded plates were held at 540 °C for 4 hr in water quenching to solution treatment them. As-extruded Al-2Li-1Cu-0.8Mg-0.1Zr-xCe (x = 0.3, 0.6, 0.9 and 1.2 wt.%) alloys are composed of Al, AlLi, AlCuLi and Al11Ce3 phases. By increasing the Ce content from 0 to 1.2 wt.%, the Al11Ce3 phase is increased, after solution treatment the AlLi and AlCuLi phases are decreased. With increasing Ce addition from 0 to 1.2 wt.%, the average grain size of the as-extruded Al alloys were decreased slightly from 100.7, 113.74, 84.3, 74.7 and 61.7 μm and ultimate tensile strength was decreased slightly from 267.59, 264.92, 237.40, 220.93 and 207.83 MPa at room temperature. After solution treatment, ultimate tensile strength was measured with 205.13, 198.12, 195.50, 198.27 and 208.01 MPa at room temperature.

Estimation of dislocation concentration in plastically deformed Al-Li based alloy by positron annihilation

International Nuclear Information System (INIS)

Abdelrahman, M.

1997-01-01

Measurements of positron annihilation mean lifetime τ have been performed on eight different specimens of Al-Li based alloy plastically deformed at room temperature up to 40% thickness reduction. This measurement shows clearly positron trapping by dislocations. The positron lifetime τ exhibits a saturation for deformations larger than (15%) thickness reduction. The fitted lifetime varies from (183±2 ps) for annealed sample to (205±2 ps) for the dislocation saturated value. Using a trapping model, the data yield the values of μ=3.83x10 -8 cm 3 s -1 for the specific trapping rate and σ=3.58x10 -15 cm 2 for the trapping cross section, some what lower than those for plastically deformed Al single crystals. The value obtained for Δτ, the increase in lifetime of positrons trapped at dislocations in plastically deformed Al-Li based alloy sample over annihilation in the annealed sample, is 22 ps. This is about 40% of the lifetime increase for the case of positrons trapped at dislocations in plastically deformed Al single crystals. Dislocation densities at different thickness reduction have been estimated. (author)

Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

Directory of Open Access Journals (Sweden)

B. Ratna Sunil

2016-12-01

Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

Intragranular nucleation sites of massive gamma grains in a TiAl-based alloy

DEFF Research Database (Denmark)

Dey, Suhash Ranjan; Bouzy, E.; Hazotte, A.

2007-01-01

Massive gamma grains were generated in a TiAl-based alloy through ice-water quenching from the alpha domain. Apart from those located along alpha(2)/alpha(2) grain boundaries, a few massive gamma grains were detected inside the alpha(2) grains. Some of these intragranular grains were revealed...

Mechanism of serrated flow in binary Al-Li alloys

Energy Technology Data Exchange (ETDEWEB)

Kumar, S.; Pink, E. [Austrian Academy of Sciences, Leoben (Austria). Erich-Schmid-Inst. of Solid State Physics; Krol, J. [Polish Academy of Sciences, Krakow (Poland). Alexander-Krupkowski-Inst. of Metallurgy and Materials Science

1996-09-15

The work on serrated flow in Al-Li alloys has given rise to a controversy--whether serrations in these alloys are caused by lithium atoms in solid solution or by {delta}{prime}(Al{sub 3}Li)-precipitates. This controversy calls for further work to clarify the mechanism of serrated flow in the Al-Li alloys. Kumar and McShane have shown that in an Al-2.5Li-2Mg-0.14Zr alloy, non-shearable {delta}{prime}-precipitates, which are obtained in the under-aged and peak-aged conditions, might directly initiate serrated flow. However, the latter result was ambiguous because of the presence of other alloying elements, and the need to work on a binary Al-Li alloy was emphasized. The present work discusses the results from the binary Al-Li alloys.

Thermodynamic aspects of grain refinement of Al-Si alloys using Ti and B

Energy Technology Data Exchange (ETDEWEB)

Groebner, Joachim [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Mirkovic, Djordje [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany); Schmid-Fetzer, Rainer [Technical University of Clausthal, Institute of Metallurgy, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2005-03-25

A thermodynamic assessment of ternary Al-Si-Ti phases was performed. Published datasets for the other subsystems were checked and adapted. Based on that, a consistent thermodynamic description of quaternary Al-Si-Ti-B alloys was generated. This was applied in a calculation of Al-Si-Ti-B phase diagram sections for practically relevant temperatures and compositions of Al-Si alloys from Al-rich to typical Al-Si foundry alloys. These stable and metastable phase diagrams could be correlated to many detailed aspects of possible reactions observed or suggested in experimental studies of grain refining. Understanding the mechanisms of grain refining of Al wrought alloys and Al-Si foundry alloys using titanium and boron requires a fundamental knowledge of both thermodynamic and kinetic aspects of this complex process. This work focuses exclusively on the thermodynamic aspects and the phase diagrams, which were not available for the quaternary alloys and partly incomplete and inconsistent for the ternary subsystems.

Fatigue and creep deformed microstructures of aged alloys based on Al-4% Cu-0.3% Mg

International Nuclear Information System (INIS)

Reddy, A. Somi

2008-01-01

The addition of 0.4 wt.% of silver or cadmium to the alloy Al-4% Cu-0.3% Mg which has a high Cu:Mg ratio, changes the nature, morphology and dispersion of the precipitates that forms on age hardening at medium temperatures such as 150-200 o C. Fatigue and creep tests were carried out on alloys aged to peak strength at 170 o C. The tensile properties of the alloys aged at 170 o C increased in the order Al-4% Cu, Al-4% Cu-0.3% Mg, Al-4% Cu-0.3% Mg-0.4% Cd, and Al-4% Cu-0.3% Mg-0.4% Ag. Despite differences in their microstructures and tensile properties, the fatigue performance of the alloys was relatively unaffected. Fatigue behaviour was similar in each case and the alloys showed identical fatigue limits. Major differences were observed in the creep performance of the alloys creep tested at 150 o C in the peak strength condition age hardened at 170 o C. Creep performance of the alloys increased in the order of their tensile properties. The purpose of the present work was to discuss the fatigue and creep deformed microstructure of these alloys

Tensile behaviour at room and high temperatures of novel metal matrix composites based on hyper eutectic Al-Si alloys

International Nuclear Information System (INIS)

Valer, J.; Rodriguez, J.M.; Urcola, J.J.

1997-01-01

This work shows the improvement obtained on tensile stress at room and high temperatures of hyper eutectic Al-Si alloys. These alloys are produced by a combination of spray-forming, extrusion and thixoforming process, in comparison with conventional casting alloys.Al-25% Si-5%Cu. Al-25%Si-5%Cu-2%Mg and Al-30%Si-5%Cu alloys have been studied relating their microstructural parameters with tensile stress obtained and comparing them with conventional Al-20%Si. Al-36%Si and Al-50%Si alloys. Al-25%Si-5%Cu alloy-was tested before and after semi-solid forming, in order to distinguish the different behaviour of this alloy due to the different microstructure. The properties obtained with these alloys were also related to Al-SiC composites formed by similar processes. (Author) 20 refs

The effects of lanthanum on microstructure and electrochemical properties of Al-Zn-In based sacrificial anode alloys

International Nuclear Information System (INIS)

Ma Jingling; Wen Jiuba

2009-01-01

In order to improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloys, Al-5Zn-0.03In-1Mg-0.05Ti-xLa (x = 0.3, 0.5 and 0.7 wt.%) alloys were developed. Microstructures and electrochemical properties of the alloys were investigated. The results show that the optimal microstructures and electrochemical properties are obtained in Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy. The main precipitate phase is Al 2 LaZn 2 particles. The excellent electrochemical properties of Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy is mainly attributed to fine grains and grain boundaries containing fine Al 2 LaZn 2 precipitates. At the same time the fine grains can improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloy.

Grain refinement of Al wrought alloys with newly developed AlTiC master alloys; Kornfeinung von Al-Knetlegierungen mit neu entwickelten AlTiC-Vorlegierungen

Energy Technology Data Exchange (ETDEWEB)

Schneider, W. [Vereinigte Aluminium-Werke AG, Bonn (Germany). Forschung und Entwicklung

2000-10-01

AlTiC master alloys are a new grain refiner type to produce an equiaxed grain structure of cast extrusion and rolling ingots. These master alloys contain Ti carbides which act as nucleants of the {alpha} solid solution during solidification. The TiC content is lower than the TiB{sub 2} content of the industrial proved AlTiB master alloys. Benefits of the AlTiC master alloys are the low agglomeration tendency of the Ti carbides in the melt and that no Zr poisoning takes place. Despite of the low Ti carbide content the grain refinement performance can be very efficient, if low melt temperatures during casting will be used and as result of this a sufficient constitutional supercooling at the solidification front is achieved. (orig.)

Martensitic Transformation and Superelasticity in Fe-Mn-Al-Based Shape Memory Alloys

Science.gov (United States)

Omori, Toshihiro; Kainuma, Ryosuke

2017-12-01

Ferrous shape memory alloys showing superelasticity have recently been obtained in two alloy systems in the 2010s. One is Fe-Mn-Al-Ni, which undergoes martensitic transformation (MT) between the α (bcc) parent and γ' (fcc) martensite phases. This MT can be thermodynamically understood by considering the magnetic contribution to the Gibbs energy, and the β-NiAl (B2) nanoprecipitates play an important role in the thermoelastic MT. The temperature dependence of critical stress for the MT is very small (about 0.5 MPa/°C) due to the small entropy difference between the parent and martensite phases in the Fe-Mn-Al-Ni alloy, and consequently, superelasticity can be obtained in a wide temperature range from cryogenic temperature to about 200 °C. Microstructural control is of great importance for obtaining superelasticity, and the relative grain size is among the most crucial factors.

Grain refinement of an AZ63B magnesium alloy by an Al-1C master alloy

Energy Technology Data Exchange (ETDEWEB)

Yichuan Pan; Xiangfa Liu; Hua Yang [The Key Lab. of Liquid Structure and Heredity of Materials, Shandong Univ., Jinan (China)

2005-12-01

In order to develop a refiner of Mg-Al alloys, an Al-1C (in wt.%) master alloy was synthesized using a casting method. The microstructure and grain-refining performance of the Al-1C master alloy were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and a grain-refining test. The microstructure of the Al-1C master alloy is composed of {alpha}-Al solid solution, Al{sub 4}C{sub 3} particles, and graphite phases. After grain refinement of AZ63B alloy by the Al-1C master alloy, the mean grain size reached a limit when 2 wt.% Al-C master alloy was added at 800 C and held for 20 min in the melt before casting. The minimum mean grain size is approximately 48 {mu}m at the one-half radius of the ingot and is about 17% of that of the unrefined alloy. The Al-1C master alloy results in better grain refinement than C{sub 2}Cl{sub 6} and MgCO{sub 3} carbon-containing refiners. (orig.)

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

International Nuclear Information System (INIS)

Ma Xiaoguang; Liu Xiangfa; Ding Haimin

2009-01-01

Because flake-like TiAl 3 particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl 3 particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of α-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption

Microstructure and mechanical properties of Mg–Al-based alloy modified with cerium

International Nuclear Information System (INIS)

Chaubey, A.K.; Scudino, S.; Prashanth, K.G.; Eckert, J.

2015-01-01

Mg 90 Al 10–x Ce x with x=0, 1, 3 and 5 (at%) have been prepared by copper mold casting and the influence of Ce on the microstructure and mechanical properties have been investigated. The addition of 1% Ce decreases the volume fraction of the γ-Mg 17 Al 12 phase and with the further increase of Ce to 3% and 5%, the γ-Mg 17 Al 12 intermetallic disappears completely with the formation of the Al 11 Ce 3 and Al 2 Ce intermetallic phases. The room temperature compression tests show that Ce addition significantly improves the room temperature mechanical properties. For example, the alloy with 5% Ce displays a strength of 448 MPa compared to 318 MPa of the binary Ce-free alloy along with appreciable plasticity of about 9%. This improvement is due to grain refinement as well as to the precipitation of the Al 11 Ce 3 and Al 2 Ce strengthening phases

Cu-Al alloy formation by thermal annealing of Cu/Al multilayer films deposited by cyclic metal organic chemical vapor deposition

Science.gov (United States)

Moon, Hock Key; Yoon, Jaehong; Kim, Hyungjun; Lee, Nae-Eung

2013-05-01

One of the most important issues in future Cu-based interconnects is to suppress the resistivity increase in the Cu interconnect line while decreasing the line width below 30 nm. For the purpose of mitigating the resistivity increase in the nanoscale Cu line, alloying Cu with traces of other elements is investigated. The formation of a Cu alloy layer using chemical vapor deposition or electroplating has been rarely studied because of the difficulty in forming Cu alloys with elements such as Al. In this work, Cu-Al alloy films were successfully formed after thermal annealing of Cu/Al multilayers deposited by cyclic metal-organic chemical vapor deposition (C-MOCVD). After the C-MOCVD of Cu/Al multilayers without gas phase reaction between the Cu and Al precursors in the reactor, thermal annealing was used to form Cu-Al alloy films with a small Al content fraction. The resistivity of the alloy films was dependent on the Al precursor delivery time and was lower than that of the aluminum-free Cu film. No presence of intermetallic compounds were detected in the alloy films by X-ray diffraction measurements and transmission electron spectroscopy.

Annex 5 - Fabrication of U-Al alloy

International Nuclear Information System (INIS)

Drobnjak, Dj.; Lazarevic, Dj.; Mihajlovic, A.

1961-01-01

Alloy U-Al with low content of aluminium is often used for fabrication of fuel elements because it is stable under moderate neutron flux density. Additionally this type of alloys show much better characteristics than pure uranium under reactor operating conditions (temperature, mechanical load, corrosion effect of water). This report contains the analysis of the phase diagram of U-Al alloy with low content of aluminium, applied procedure for alloying and casting with detailed description of equipment. Characteristics of the obtained alloy are described and conclusions about the experiment and procedure are presented [sr

Corrosion behaviour of Al-Fe-Ti-V medium entropy alloy

Science.gov (United States)

Bodunrin, M. O.; Obadele, B. A.; Chown, L. H.; Olubambi, P. A.

2017-12-01

Alloys containing up to four multi-principal elements in equiatomic ratios are referred to as medium entropy alloys (MEA). These alloys have attracted the interest of many researchers due to the superior mechanical properties it offers over the traditional alloys. The design approach of MEA often results to simple solid solution with either body centered cubic; face centered cubic structures or both. As the consideration for introducing the alloys into several engineering application increases, there have been efforts to study the corrosion behaviour of these alloys. Previous reports have shown that some of these alloys are more susceptible to corrosion when compared with traditional alloys due to lack of protective passive film. In this research, we have developed AlFeTiV medium entropy alloys containing two elements (Ti and Al) that readily passivate when exposed to corrosive solutions. The alloys were produced in vacuum arc furnace purged with high purity argon. Open circuit potential and potentiodynamic polarisation tests were used to evaluate the corrosion behaviour of the as-cast AlFeTiV alloy in 3.5 wt% NaCl and 1 M H2SO4. The corrosion performance of the alloy was compared with Ti-6Al-4V alloy tested under similar conditions. The results show that unlike in Ti-6Al-4V alloy, the open circuit potential of the AlFeTiV alloy move towards the negative values in both 3.5 wt% NaCl and 1 M H2SO4 solutions indicating that self-activation occurred rapidly on immersion. Anodic polarisation of the alloys showed that AlFeTiV alloy exhibited a narrow range of passivity in both solutions. In addition, the alloys exhibited lower Ecorr and higher Icorr when compared with traditional Ti-6Al-4V alloy. The traditional Ti-6Al-4V alloy showed superior corrosion resistant to the AlFeTiV alloy in both 3.5 wt.% NaCl and 1 M H2SO4 solutions.

Alpha and beta stabilizer character of Al in Zr-Nb-Al alloys

International Nuclear Information System (INIS)

Peruzzi Bardella, A.; Bolcich, J.C.

1987-01-01

The T β/α+β of Zr5Nb and Zr5Nb2Al (weight %) were determined in order to observe the alpha-stabilizer character of Al in ternary Zr-Nb-Al alloys. Techniques employed were change of resistivity with temperature in dynamic experiences, and metallography of samples quenched to room temperature after isothermal annealings. The T β/α+β of the ternary resulted 17 ± 8 deg C higher than that of the binary alloy. In addition, taking into account the results of previous investigations of the transformation of beta on quenching Zr-Nb-Al alloys from the beta field to room temperature, it is concluded that the beta-stabilizer character of Nb is stronger than the alpha-stabilizer character of Al in these Zr alloys, and that the Al can have important influence on the mechanical properties by the appearance of TRIP effect. (Author) [es

Antimony Influence on Shape of Eutectic Silicium in Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2017-12-01

Full Text Available Liquid AI-Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved properties. For many years, sodium additions to hypoeutectic and eutectic AI-Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic structure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI-Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non-fading refining ability. In this paper, the authors summarize work on antimony treatment of Al-Si based alloys.

Iron Intermetallic Phases in the Alloy Based on Al-Si-Mg by Applying Manganese

Directory of Open Access Journals (Sweden)

Podprocká R.

2017-09-01

Full Text Available Manganese is an effective element used for the modification of needle intermetallic phases in Al-Si alloy. These particles seriously degrade mechanical characteristics of the alloy and promote the formation of porosity. By adding manganese the particles are being excluded in more compact shape of “Chinese script” or skeletal form, which are less initiative to cracks as Al5FeSi phase. In the present article, AlSi7Mg0.3 aluminium foundry alloy with several manganese content were studied. The alloy was controlled pollution for achieve higher iron content (about 0.7 wt. % Fe. The manganese were added in amount of 0.2 wt. %, 0.6 wt. %, 1.0 wt. % and 1.4 wt. %. The influence of the alloying element on the process of crystallization of intermetallic phases were compared to microstructural observations. The results indicate that increasing manganese content (> 0.2 wt. % Mn lead to increase the temperature of solidification iron rich phase (TAl5FeSi and reduction this particles. The temperature of nucleation Al-Si eutectic increase with higher manganese content also. At adding 1.4 wt. % Mn grain refinement and skeleton particles were observed.

Positive effect of yttrium on the reduction of pores in cast Al alloy

International Nuclear Information System (INIS)

Hua, Guomin; Ahmadi, Hojat; Nouri, Meisam; Li, Dongyang

2015-01-01

Mechanical and electrochemical properties of Al alloys can be improved by adding a small amount of rare-earth such as yttrium. Here we demonstrate that adding yttrium also helps suppress the porosity in cast Al alloys, thus minimizing its detrimental effect on mechanical properties of the alloys. The mechanism behind is elucidated based on the hydrogen binding energies and the diffusion activation energies of hydrogen atoms in Al and Al–Y phases, calculated using the first-principle method. - Highlights: • The porosity of commercial Al alloy can be reduced by additive yttrium. • Formed Al 3 Y phase helps reduce homogeneous nucleation of hydrogen bubbles. • Formed Al 3 Y and Al 2 Y phases could suppress the growth of hydrogen bubbles

Effect of in-situ formed Al3Ti particles on the microstructure and mechanical properties of 6061 Al alloy

Science.gov (United States)

Gupta, Rahul; Chaudhari, G. P.; Daniel, B. S. S.

2018-03-01

In this study, in situ Titanium-tri-aluminide (Al3Ti) particles reinforced Al 6061 alloy matrix composites were fabricated by the reaction of potassium hexafluorotitanate (K2TiF6) inorganic salt with molten Al 6061 alloy via liquid metallurgy route. The development of in-situ Al3Ti particles and their effects on the mechanical properties such as yield strength (YS), ductility, ultimate tensile strength (UTS) and hardness, and microstructure of Al 6061 alloy were studied. It was observed from the results that in-situ formed Al3Ti particles were blocky in morphology whose average size was around 2.6 ± 1.1 μm. Microstructure studies showed that grain size of Al matrix was reduced due to the nucleating effect of Al3Ti particles. It was observed from the mechanical properties analysis that when the volume fraction of Al3Ti particles was increased, the hardness, UTS and YS of the composites were also increased as compared to that of Al 6061 alloy. An improvement in ductility was observed with the dispersion of Al3Ti particles in base alloy which is contrary to many other composites.

A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

Energy Technology Data Exchange (ETDEWEB)

Ma Xiaoguang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn; Ding Haimin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2009-03-05

Because flake-like TiAl{sub 3} particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl{sub 3} particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of {alpha}-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption.

Molecular dynamics study of interstitial-solute interactions in irradiated Al-based alloys

International Nuclear Information System (INIS)

Doan, N.V.; Lam, N.Q.; Dagens, L.; Adda, Y.

1981-11-01

The stable configurations and binding energies of interstitial and di-interstitial-solute complexes in Al-Be, Al-Ca, Al-K, Al-Li, Al-Mg and Al-Zn alloys were calculated using the molecular dynamics technique in conjunction with interatomic potentials derived entirely from theoretical considerations and not fitted to any experimental data. All the results reported in this work are thus of first-principles nature

Density of liquid NiCrAlMo quarternary alloys measured by a modified sessile drop method

International Nuclear Information System (INIS)

Fang, L.; Wang, Y.F.; Xiao, F.; Tao, Z.N.; MuKai, K.

2006-01-01

The densities of liquid NiCrAlMo quaternary alloys with a fixed molar ratio of Ni:Cr:Al (approximately as 73:14:13) and molybdenum concentration from 0 to 10 mass% were measured by a modified sessile drop method (MSDM). It was found that the density of the liquid NiCrAlMo quaternary alloys decreases with increasing temperature, but increases with the increase of molybdenum concentration. The molar volume of liquid NiCrAlMo quaternary alloys increases with the increase of temperature and molybdenum concentration. The density of liquid NiCrAlMo quaternary alloys calculated from the partial molar volumes of nickel, chromium, aluminum and molybdenum in the corresponding Ni-based binary alloys are in good agreement with the experimental results, means, within the error tolerance range the density of liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state

Structural features in Ni-Al alloys

International Nuclear Information System (INIS)

Abylkalykova, R.B.; Kveglis, L.I.; Rakhimova, U.A.; Nasokhova, Sh.B.; Tazhibaeva, G.B.

2007-01-01

Purpose of the work is study of structural transformations under diverse memory effect in Ni-Al alloys. Examination were conducted in following composition samples: Ni -75 at.% and Al - 25 at.%. The work is devoted to clarification reasons both formation atom-ordered structures in inter-grain boundaries of bulk samples under temperature action and static load. Revealed inter-grain inter-boundary layers in Ni-Al alloy both bulk and surface state have complicated structure

Development of a TiAl Alloy by Spark Plasma Sintering

Science.gov (United States)

Couret, Alain; Voisin, Thomas; Thomas, Marc; Monchoux, Jean-Philippe

2017-12-01

Spark plasma sintering (SPS) is a consolidated powder metallurgy process for which the powder sintering is achieved through an applied electric current. The present article aims to describe the method we employed to develop a TiAl-based alloy adjusted for this SPS process. Owing to its enhanced mechanical properties, this alloy was found to fully match the industrial specifications for the aeronautic and automotive industries, which require a high strength at high temperature and a reasonably good ductility at room temperature. A step-by-step method was followed for this alloy development. Starting from a basic study on the as-SPSed GE alloy (Ti-48Al-2Cr-2Nb) in which the influence of the microstructure was studied, the microstructure-alloy composition relationships were then investigated to increase the mechanical properties. As a result of this study, we concluded that tungsten had to be the major alloying element to improve the resistance at high temperature and a careful addition of boron would serve the properties at room temperature. Thus, we developed the IRIS alloy (Ti-48Al-2W-0.08B). Its microstructure and mechanical properties are described here.

Solute partitioning and interfacial segregation in TiAl-based alloys

International Nuclear Information System (INIS)

Larson, D.J.; Miller, M.K.

1999-01-01

Atom probe microscopy has been used to investigate elemental partitioning and segregation behavior in a TiAl-based alloy with a variety of alloying additions including Cr, Nb, W and B. These results indicate that in a stress-relieved state (2h at 900 C) and a reheated state (2h at 900 C, 2,184h at 800 C and 2h at 1,210 C) chromium, and to a lesser extent tungsten, is partitioned to the α 2 phase. However, in an annealed state (2h at 900 C and 720 h at 800 C), these elements are partitioned to the γ phase. Segregation of chromium and tungsten to lamellar interfaces is observed in the stress-relieved material, but significant segregation was not observed in material subjected to the other heat treatments. A W- and B-enriched precipitate was observed in the reheated material and provides a possible explanation for the low tungsten concentrations measured in the matrix phases

Grain Refinement of an Al-2 wt%Cu Alloy by Al3Ti1B Master Alloy and Ultrasonic Treatment

International Nuclear Information System (INIS)

Wang, E Q; Wang, G; Dargusch, M S; StJohn, D H; Qian, M; Eskin, D G

2016-01-01

Both inoculation by AlTiB master alloys and Ultrasonic Treatment (UT) are effective methods of refining the grain size of aluminium alloys. The present study investigates the influence of UT on the grain refinement of an Al-2 wt% Cu alloy with a range of Al3TilB master alloy additions. When the alloy contains the smallest amount of added master alloy, UT caused significant additional grain refinement compared with that provided by the master alloy only. However, the influence of UT on grain size reduces with increasing addition of the master alloy. Plotting the grain size data versus the inverse of the growth restriction factor (Q) reveals that the application of UT causes both an increase in the number of potentially active nuclei and a decrease in the size of the nucleation free zone due to a reduction in the temperature gradient throughout the melt. Both these factors promote the formation of a fine equiaxed grain structure. (paper)

Compressive performance and crack propagation in Al alloy/Ti{sub 2}AlC composites

Energy Technology Data Exchange (ETDEWEB)

Hanaor, D.A.H., E-mail: dorian.hanaor@sydney.edu.au [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Hu, L. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Kan, W.H.; Proust, G. [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Foley, M. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Karaman, I.; Radovic, M. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States)

2016-08-30

Composite materials comprising a porous Ti{sub 2}AlC matrix and Al 6061 alloy were fabricated by a current-activated pressure assisted melt infiltration process. Coarse, medium and fine meso-structures were prepared with Al alloy filled pores of differing sizes. Materials were subjected to uniaxial compressive loading up to stresses of 668 MPa, leading to the failure of specimens through crack propagation in both phases. As-fabricated and post-failure specimens were analysed by X-ray microscopy and electron microscopy. Quasi-static mechanical testing results revealed that compressive strength was the highest in the fine structured composite materials. While the coarse structured specimens exhibited a compressive strength of 80% relative to this. Reconstructed micro-scale X-ray tomography data revealed different crack propagation mechanisms. Large planar shear cracks propagated throughout the fine structured materials while the coarser specimens exhibited networks of branching cracks propagating preferentially along Al alloy-Ti{sub 2}AlC phase interfaces and through shrinkage pores in the Al alloy phase. Results suggest that control of porosity, compensation for Al alloy shrinkage and enhancement of the Al alloy-Ti{sub 2}AlC phase interfaces are key considerations in the design of high performance metal/Ti{sub 2}AlC phase composites.

Stretch strength of Al-Li alloy sheet

Energy Technology Data Exchange (ETDEWEB)

Sato, K.; Sawa, Y.; Yokoyama, T.; Fujimoto, S. [Science Univ. of Tokyo (Japan). Dept. of Mech. Eng.; Sakamoto, T. [Kobe Steel Works, Tokyo (Japan)

1998-07-01

Stretch test on Al-Li alloy sheet was carried out in stretch rate of 0.01 to 0.2 mm/sec. The limiting stretch depth was measured in various conditions and the following results were obtained. (1) Stretch rate does not affect the limiting stretch depth of Al-Li alloy. (2) The limiting stretch depth is increased with increase of the profile radius. (3) Strain hardening exponent(n-value) and r-value of Lankford do not affect the limiting stretch depth. (4) Rapture pattern in stretch test of Al is {alpha} type rapture and that of Al-Li alloy is straight line type rapture. (orig.) 4 refs.

Fragility and structure of Al-Cu alloy melts

International Nuclear Information System (INIS)

Lv Xiaoqian; Bian Xiufang; Mao Tan; Li Zhenkuan; Guo Jing; Zhao Yan

2007-01-01

The dynamic viscosity measurements are performed for Al-Cu alloy melts with different compositions using an oscillating-cup viscometer. The results show that the viscosities of Al-Cu alloy melts increase with the copper content increasing, and also have a correlation with the correlation radius of clusters, which is measured by the high-temperature X-ray diffractometer. It has also been found that the fragilities of superheated melts (M) of hypereutectic Al-Cu alloys increase with the copper content increasing. There exists a relationship between the fragility and the structure in Al-Cu alloy melts. The value of the M reflects the variation of activation energy for viscous flow

Electron beam and laser surface alloying of Al-Si base alloys

International Nuclear Information System (INIS)

Vanhille, P.; Tosto, S.; Pelletier, J.M.; Issa, A.; Vannes, A.B.; Criqui, B.

1992-01-01

Surface alloying on aluminium-base alloys is achieved either by using an electron beam or a laser beam, in order to improve the mechanical properties of the near-surface region. A predeposit of nickel is first realized by plasma spraying. Melting of both the coating and part of the substrate produces a surface alloy with a fine, dendritic microstructure with a high hardness. Enhancement of this property requires an increase in the nickel content. Various problems occur during the formation of nickel-rich surface layers: incomplete homogenization owing to a progressive increase of the liquidus temperature, cracks owing to the brittleness of this hard suface alloy, formation of a plasma when experiments are carried out in a gaseous environment (laser surface alloying). Nevertheless, various kinds of surface layers may be achieved; for example very hard surface alloys (HV 0.2 =900), with a thickness of about 500-600 μm, or very thick surface alloys (e>2 mm), with a fairly good hardness (greater than 350 HV 0.2 ). Thus, it is possible to obtain a large variety of new materials by using high energy beams on aluminium substrates. (orig.)

Oxidation properties of laser clad Nb-Al alloys

International Nuclear Information System (INIS)

Tewari, S.K.; Mazumder, J.

1992-01-01

This paper reports on laser cladding parameters for non-equilibrium synthesis for several ternary and complex Nb-Al base alloys containing Ti, Cr, Si, Ni, B and C that have been established. Phase transformations occurring below 1500 degrees C have been determined using differential thermal analysis. Ductility of the clads is qualitatively evaluated from the extent of cracking around the microhardness indentations. Oxidation resistance of the clads in flowing air is measured at 800 degrees C, 1200 degrees C and 1400 degrees C and parabolic rate constants are calculated. Microstructure of the clads is studied using optical and scanning electron microscopes. X-ray diffraction and EDX techniques are used for identification of the oxides formed and the phases formed in as clad material. Oxide morphology is studied using SEM. Effect of alloying additions on the ductility and oxidation resistance of the laser clad Nb-Al alloys is discussed. The results are compared with those reported in literature for similar alloys produced by conventional processing methods

Development of Al-Mg-Li alloys for fusion reactor

International Nuclear Information System (INIS)

Shoji, Yoshifusa; Yoshida, Hideo; Uno, Teruo; Baba, Yoshio; Kamada, Koji.

1985-01-01

Aluminum-magnesium-lithium alloys featuring low residual induced radioactivity and high electrical resistivity have been developed for fusion reactor structural materials. The addition of lithium in aluminum and Al-Mg alloys markedly increases electrical resistivity and tensile strength of them. However the elongation of Al-Mg-Li alloys containing more than 2 mass% lithium are less than 10 %. The Al-4--5 mass%Mg-1 mass%Li alloys are optimum for fusion reactor materials, and exhibit high resistivity (86 nΩm: 20 %IACS), medium strength (300 MPa) and good formability (22 % elongation). The variation of electrical resistivity of Al-Li and Al-Mg-Li alloys in solid solution can be approximated by the Matthiessen's rule. (author)

The impact of major alloying elements and refiner on the SDAS of Al-Si-Cu alloy; Der Einfluss von Hauptlegierungselementen und Kornfeinern auf den sekundaeren Dendritenarmabstand der Al-Si-Cu-Legierung

Energy Technology Data Exchange (ETDEWEB)

Djurdjevic, Mile; Byczynski, Glenn [Nemak Europe GmbH, Frankfurt am Main (Germany). Frankfurt Airport Center 1; Pavlovic, Jelena [Magdeburg Univ. (Germany). Inst. fuer Fertigungstechnik und Qualitaetssicherung

2009-02-15

This paper investigates the effect of some major alloying elements (silicon and copper) and the effect of grain refiner (titanium boride) on the size of the secondary dendrite arm spacing (SDAS) in series of Al-Si-Cu alloys. It has been shown that both silicon and copper have significant influence on this solidification parameter. The addition of grain refining master alloys to aluminium alloys is common practice in many commercial foundries aiming to reduce the grain size of Al-Si alloys. However, it was shown in the present paper that master alloy based on TiB had an unexpected impact on the SDAS, decreasing the size of SDAS. In addition, there is a minimum of SDAS corresponding to the presence of 0.12 wt% of titanium in Al-Si alloy. Such findings could have important implications for Al-Si alloys in particular, due to their wide spread applications in the automotive industry. (orig.)

Experimental Studies on Al (5.7% Zn) Alloy based Hybrid MMC

Science.gov (United States)

Shivaprakash, Y. M.; Ramu, H. C.; Chiranjivee; Kumar, Roushan; Kumar, Deepak

2018-02-01

In this investigation, an attempt is made to disperse SiC (20-25 microns) and Gr (15-20 microns) in the aluminium alloy having Zn, Mg and coper as major alloying elements. The composite is further subjected to mechanical testing to determine various properties like hardness, tensile strength and wear resistance. The alloy and composite samples were tested in the un heat treated conditions. All the tests were done at the laboratory conditions as per ASTM standards. The Pin-On-Disc tribometer is used to test the two-body abrasive sliding wear behaviour in dry conditions. The wear pattern is analysed by the optical images of worn surface taken in an inverted metallurgical microscope. The calculated density is found to be reducing as the SiC and Gr quantity is increased in the base alloy. The as cast Al alloy was found to be having highest hardness. The introduction of SiC tend to increase the hardness and UTS, since Gr is also introduced simultaneously which tends to reduce the hardness and UTS of composite. The composite having highest quantity of Gr showed superior wear resistance which is mainly because the Gr particulates provide an inbuilt lubricating properties to composite. The analysis of images of worn surface showed the abrasive and delamination pattern of wear. The composites developed in the present work can be used in the automobile and aerospace parts that are light in weight and require self-lubricating properties to enhance the wear resistance.

Microstructure and mechanical properties of Mg–Al-based alloy modified with cerium

Energy Technology Data Exchange (ETDEWEB)

Chaubey, A.K., E-mail: anil.immt@gmail.com [Institute of Minerals and Materials Technology (IMMT), Bhubaneswar 751013 (India); Scudino, S.; Prashanth, K.G. [IFW Dresden, Institut für Komplexe Materialien, Postfach 270116, D-01171 Dresden (Germany); Eckert, J. [IFW Dresden, Institut für Komplexe Materialien, Postfach 270116, D-01171 Dresden (Germany); TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden (Germany)

2015-02-11

Mg{sub 90}Al{sub 10–x}Ce{sub x} with x=0, 1, 3 and 5 (at%) have been prepared by copper mold casting and the influence of Ce on the microstructure and mechanical properties have been investigated. The addition of 1% Ce decreases the volume fraction of the γ-Mg{sub 17}Al{sub 12} phase and with the further increase of Ce to 3% and 5%, the γ-Mg{sub 17}Al{sub 12} intermetallic disappears completely with the formation of the Al{sub 11}Ce{sub 3} and Al{sub 2}Ce intermetallic phases. The room temperature compression tests show that Ce addition significantly improves the room temperature mechanical properties. For example, the alloy with 5% Ce displays a strength of 448 MPa compared to 318 MPa of the binary Ce-free alloy along with appreciable plasticity of about 9%. This improvement is due to grain refinement as well as to the precipitation of the Al{sub 11}Ce{sub 3} and Al{sub 2}Ce strengthening phases.

Production and properties of light-metal base amorphous alloys

International Nuclear Information System (INIS)

Inoue, Akihisa; Masumoto, Tsuyoshi

1993-01-01

Light-metal base alloys with high specific strength and good corrosion resistance were produced through amorphization of Al and Mg-based alloys. The amorphous phase is formed in rapidly solidified Al-TM-Ln and Mg-TM-Ln (TM=transition metal, Ln=lanthanide metal) alloys. The highest tensile strength (σ f ) reaches 1,330 MPa for the Al base and 830 MPa for the Mg base. Furthermore, the Mg-based alloys have a large glass-forming capacity which enables to produce an amorphous phase by a metallic mold casting method. The extrusion of the Al-based amorphous powders at temperatures above crystallization temperature caused the formation of high strength materials with finely mixed structure consisting of dispersed intermetallic compounds in an Al matrix. The highest values of σ f and fatigue limit are as high as 940 and 313 MPa, respectively, at room temperature and 520 and 165 MPa at 473 K. The extruded Al-Ni-Mm alloy has already been used as machine parts and subsequent further development as practical materials is expected by taking these advantages

Fabrication and Magnetic Properties of Co₂MnAl Heusler Alloys by Mechanical Alloying.

Science.gov (United States)

Lee, Chung-Hyo

2018-02-01

We have applied mechanical alloying (MA) to produce nanocrystalline Co2MnAl Heusler alloys using a mixture of elemental Co50Mn25Al25 powders. An optimal milling and heat treatment conditions to obtain a Co2MnAl Heusler phase with fine microstructure were investigated by X-ray diffraction, differential scanning calorimeter and vibrating sample magnetometer measurements. α-(Co, Mn, Al) FCC phases coupled with amorphous phase are obtained after 3 hours of MA without any evidence for the formation of Co2MnAl alloys. On the other hand, a Co2MnAl Heusler alloys can be obtained by the heat treatment of all MA samples up to 650 °C. X-ray diffraction result shows that the average grain size of Co2MnAl Heusler alloys prepared by MA for 5 h and heat treatment is in the range of 95 nm. The saturation magnetization of MA powders decreases with MA time due to the magnetic dilution by alloying with nonmagnetic Mn and Al elements. The magnetic hardening due to the reduction of the grain size with ball milling is also observed. However, the saturation magnetization of MA powders after heat treatment increases with MA time and reaches to a maximum value of 105 emu/g after 5 h of MA. It can be also seen that the coercivity of 5 h MA sample annealed at 650 °C is fairly low value of 25 Oe.

First-principles calculations of bulk and interfacial thermodynamic properties for fcc-based Al-Sc alloys

International Nuclear Information System (INIS)

Asta, M.; Foiles, S.M.; Quong, A.A.

1998-01-01

The configurational thermodynamic properties of fcc-based Al-Sc alloys and coherent Al/Al 3 Sc interphase-boundary interfaces have been calculated from first principles. The computational approach used in this study combines the results of pseudopotential total-energy calculations with a cluster-expansion description of the alloy energetics. Bulk and interface configurational-thermodynamic properties are computed using a low-temperature-expansion technique. Calculated values of the {100} and {111} Al/Al 3 Sc interfacial energies at zero temperature are, respectively, 192 and 226mJ/m 2 . The temperature dependence of the calculated interfacial free energies is found to be very weak for {100} and more appreciable for {111} orientations; the primary effect of configurational disordering at finite temperature is to reduce the degree of crystallographic anisotropy associated with calculated interfacial free energies. The first-principles-computed solid-solubility limits for Sc in bulk fcc Al are found to be underestimated significantly in comparison with experimental measurements. It is argued that this discrepancy can be largely attributed to nonconfigurational contributions to the entropy which have been neglected in the present thermodynamic calculations. copyright 1998 The American Physical Society

Calculation of glass forming ranges in Al-Ni-RE (Ce, La, Y) ternary alloys and their sub-binaries based on Miedema's model

International Nuclear Information System (INIS)

Sun, S.P.; Yi, D.Q.; Liu, H.Q.; Zang, B.; Jiang, Y.

2010-01-01

Research highlights: → A method based on semi-empirical Miedema's and Toop's model for predicting glass forming range of ternary alloy system has been systematically described. → The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. → The glass forming ranges of Al-Ni-RE (Al-Ni-Ce, Al-Ni-Y and Al-Ni-La) systems and their sub-binaries have been successfully calculated. → The present calculations using the method are in well agreement with experiments. → This model is especially useful for predicting the glass forming range of ternary alloy system because the calculations do not require experimental data. - Abstract: A method based on the semi-empirical Miedema's and Toop's model for calculating the glass forming range of a ternary alloy system was systematically described. The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. Using this method, the glass forming ranges of Al-Ni-RE (Ce, La, Y) systems and their sub-binaries were successfully predicted. The mixing enthalpy and mismatch entropy were calculated, and their effects on the glass forming abilities of Al-Ni-RE (Ce, La, Y) systems were also discussed. The glass forming abilities of Al-Ni-Ce, Al-Ni-La and Al-Ni-Y are found to be close. The calculated glass forming ranges agree with experiments well. Meanwhile, the enthalpy change from amorphous phase to solid solution in the glass forming ranges was calculated, and the results suggest that those alloys close to the Ni-RE sub-binary system have higher glass forming abilities.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability.

Science.gov (United States)

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-11-05

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Preparation of a high strength Al-Cu-Mg alloy by mechanical alloying and press-forming

Energy Technology Data Exchange (ETDEWEB)

Tang Huaguo [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Cheng Zhiqiang [College of Resources and Environment, Jilin Agricultural University, Changchun 130118 (China); Liu Jianwei [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Ma Xianfeng, E-mail: xfma@ciac.jl.cn [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

2012-07-30

Highlights: Black-Right-Pointing-Pointer A high strength aluminum alloy of Al-2 wt.%Mg-2 wt.%Cu has been prepared by mechanical alloying and press-forming. Black-Right-Pointing-Pointer The alloy only consists of solid solution {alpha}-Al. Black-Right-Pointing-Pointer The grains size of {alpha}-Al was about 300 nm-5 {mu}m. Black-Right-Pointing-Pointer The solid solution strengthening and the grain refinement strengthening are the main reasons for such a high strength. - Abstract: A high strength aluminum alloy, with the ratio of 96 wt.%Al-2 wt.%Mg-2 wt.%Cu, has been prepared by mechanical alloying and press-forming. The alloy exhibited a high tensile strength of 780 MPa and a high microhardness of 180 HV. X-ray diffraction characterizations confirmed that the alloy only consists of a solid solution {alpha}-Al. Microstructure characterizations revealed that the grain size of {alpha}-Al was about 300 nm-5 {mu}m. The solid solution strengthening and the grain refinement strengthening were considered to be the reason for such a high strength.

Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by MgGa δ doping in (AlN)m/(GaN)n superlattice

OpenAIRE

Xiao Wang; Wei Wang; Jingli Wang; Hao Wu; Chang Liu

2017-01-01

P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)5/(GaN)1 superlattice (SL) in Al0.83Ga0.17N disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as MgG...

Microstructure and properties of Mg-Al binary alloys

Directory of Open Access Journals (Sweden)

ZHENG Wei-chao

2006-11-01

Full Text Available The effects of different amounts of added Al, ranging from 1 % to 9 %, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

Precipitation kinetics of lamellar (γ) laths in a TiAl-base alloy

International Nuclear Information System (INIS)

Zhang, W.J.; Francesconi, L.; Evangelista, E.

1997-01-01

Titanium aluminide is a candidate material for high temperature applications. Although different types of microstructure have been produced in TiAl-base alloys, the fully-lamellar structure is currently regarded as the most attractive. This kind of microstructure can be characterized by the factors, namely, colony size, lamellar interspacing, the existence of Widmanstatten (secondary) laths, and the type of grain boundaries (smooth or interlocking). The objective of this paper is to examine the nucleation and growth kinetics of γ lamellar laths during continuous and isothermal cooling. These data are expected to benefit the understanding of the transformation mechanism and the design of lamellar TiAl microstructure for industrial application

Development of ODS-Fe{sub 3}Al alloys

Energy Technology Data Exchange (ETDEWEB)

Wright, I.G.; Pint, B.A.; Tortorelli, P.F.; McKamey, C.G. [Oak Ridge National Lab., TN (United States)

1997-12-01

The overall goal of this program is to develop an oxide dispersion-strengthened (ODS) version of Fe{sub 3}Al that has sufficient creep strength and resistance to oxidation at temperatures in the range 1000 to 1200 C to be suitable for application as heat exchanger tubing in advanced power generation cycles. The main areas being addressed are: (a) alloy processing to achieve the desired alloy grain size and shape, and (b) optimization of the oxidation behavior to provide increased service life compared to semi-commercial ODS-FeCrAl alloys intended for the same applications. The recent studies have focused on mechanically-alloyed powder from a commercial alloy vendor. These starting alloy powders were very clean in terms of oxygen content compared to ORNL-produced powders, but contained similar levels of carbon picked up during the milling process. The specific environment used in milling the powder appears to exert a considerable influence on the post-consolidation recrystallization behavior of the alloy. A milling environment which produced powder particles having a high surface carbon content resulted in a consolidated alloy which readily recrystallized, whereas powder with a low surface carbon level after milling resulted in no recrystallization even at 1380 C. A feature of these alloys was the appearance of voids or porosity after the recrystallization anneal, as had been found with ORNL-produced alloys. Adjustment of the recrystallization parameters did not reveal any range of conditions where recrystallization could be accomplished without the formation of voids. Initial creep tests of specimens of the recrystallized alloys indicated a significant increase in creep strength compared to cast or wrought Fe{sub 3}Al, but the specimens failed prematurely by a mechanism that involved brittle fracture of one of the two grains in the test cross section, followed by ductile fracture of the remaining grain. The reasons for this behavior are not yet understood. The

Enhanced hardness in epitaxial TiAlScN alloy thin films and rocksalt TiN/(Al,Sc)N superlattices

Energy Technology Data Exchange (ETDEWEB)

Saha, Bivas [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Lawrence, Samantha K.; Bahr, David F. [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Schroeder, Jeremy L.; Birch, Jens [Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Sands, Timothy D. [School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-10-13

High hardness TiAlN alloys for wear-resistant coatings exhibit limited lifetimes at elevated temperatures due to a cubic-AlN to hexagonal-AlN phase transformation that leads to decreasing hardness. We enhance the hardness (up to 46 GPa) and maximum operating temperature (up to 1050 °C) of TiAlN-based coatings by alloying with scandium nitride to form both an epitaxial TiAlScN alloy film and epitaxial rocksalt TiN/(Al,Sc)N superlattices on MgO substrates. The superlattice hardness increases with decreasing period thickness, which is understood by the Orowan bowing mechanism of the confined layer slip model. These results make them worthy of additional research for industrial coating applications.

Study on Microstructure and Mechanical Properties of Hypereutectic Al-18Si Alloy Modified with Al-3B.

Science.gov (United States)

Gong, Chunjie; Tu, Hao; Wu, Changjun; Wang, Jianhua; Su, Xuping

2018-03-20

An hypereutectic Al-18Si alloy was modified via an Al-3B master alloy. The effect of the added Al-3B and the modification temperature on the microstructure, tensile fracture morphologies, and mechanical properties of the alloy were investigated using an optical microscope, Image-Pro Plus 6.0, a scanning electron microscope, and a universal testing machine. The results show that the size of the primary Si and its fraction decreased at first, and then increased as an additional amount of Al-3B was added. When the added Al-3B reached 0.2 wt %, the fraction of the primary Si in the Al-18Si alloy decreased with an increase in temperature. Compared with the unmodified Al-18Si alloy, the tensile strength and elongation of the alloy modified at 850 °C with 0.2 wt % Al-3B increased by 25% and 81%, respectively. The tensile fracture of the modified Al-18Si alloy exhibited partial ductile fracture characteristics, but there were more areas with ductile characteristics compared with that of the unmodified Al-18Si alloy.

Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

International Nuclear Information System (INIS)

Kalay, Yunus Eren

2008-01-01

Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T 0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T 0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 (micro)m with a Peclet number of ∼0.2, JH and TMK deviate from each other. This

Spray cast Al-Si base alloys for stiffness and fatigue strength requirements

International Nuclear Information System (INIS)

Courbiere, M.; Mocellin, A.

1993-01-01

Hypereutectic AlSiFe spray-cast alloys exhibit properties similar to those of metal-matrix composite (MMC's) : high Young's modulus and a low coefficient of thermal expansion. These physical properties can be adjusted by changing the Si content of the alloy. The refinement of the microstructure is produced by formation of a large amount of nuclei in the spray. Consolidation done by extrusion (bars, tubes or profiles) and/or forging leads to high mechanical properties, especially very good dynamic properties. High fatigue properties coupled with high modulus, good high temperature behaviour and low thermal expansion, allow their use for applications in the automotive industry. In opposition to MMC's, these materials present the advantage of easy recycling and easy machinability as it is the case for the conventional AlSi alloys. The low oxygen content allows quality joining with conventional arc welding techniques. (orig.)

Effect of the addition of Al-Ti-C master alloy on the microstructure and microhardness of a cast Al-10Mg alloy

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-l0Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition.It was found that this level of the master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness of the Al-10Mg alloy.Microchemical analysis revealed that TiC particles existed in the grain center.The relationship between the holding time and grain size was also studied.It shows that the grain refining efficiency is faded observably with the holding time.This is explained in terms of the instability of TiC particles.

Al-Cu-Li and Al-Mg-Li alloys: Phase composition, texture, and anisotropy of mechanical properties (Review)

Science.gov (United States)

Betsofen, S. Ya.; Antipov, V. V.; Knyazev, M. I.

2016-04-01

The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al-Cu-Li and Al-Mg-Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S1 (Al2MgLi), T1 (Al2CuLi), and δ' (Al3Li) phases. The fraction of the δ' phase in Al-Cu-Li alloys is shown to be significantly higher than in Al-Mg-Li alloys. Therefore, the role of the T1 phase in the hardening of Al-Cu-Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al-Cu-Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al-Cu-Li and Al-Mg-Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.

Rapidly solidified Ti-25Al-Nb alloys

International Nuclear Information System (INIS)

Ward, C.H.; Broderick, T.F.; Jackson, A.G.; Rowe, R.G.; Froes, F.H.

1987-01-01

Alloys based on the Ti-25Al-Nb intermetallic system were studied to determine the effects of rapid solidification on structure. Compositions ranging from 12 to 30 at% niobium which are beyond the α/sub 2/ single phase field were evaluated. Alloys were prepared using a melt spinning process. The resulting ribbons were characterized using transmission electron microscopy and x-ray diffraction. The alloys were all found to have a retained ordered B2 structure in the melt spun condition with an antiphase domain size that significantly decreased with increasing niobium content. ''Tweed-like'' striations, indicating planar shear strain, were observed in all compositions. The characteristic diffraction pattern of an ordered ''omega-type'' phase was found to occur in the patterns taken from the 12 at% niobium alloy

Thermodynamic analysis of 6xxx series Al alloys: Phase fraction diagrams

Directory of Open Access Journals (Sweden)

Cui S.

2018-01-01

Full Text Available Microstructural evolution of 6xxx Al alloys during various metallurgical processes was analyzed using accurate thermodynamic database. Phase fractions of all the possible precipitate phases which can form in the as-cast and equilibrium states of the Al-Mg-Si-Cu-Fe-Mn-Cr alloys were calculated over the technically useful composition range. The influence of minor elements such as Cu, Fe, Mn, and Cr on the amount of each type of precipitate in the as-cast and equilibrium conditions were analyzed. Phase fraction diagrams at 500 °C were mapped in the composition range of 0-1.1 wt.% Mg and 0-0.7 wt.% Si to investigate the as-homogenized microstructure. In addition, phase fraction diagram of Mg2Si at 177 °C was mapped to understand the microstructure after final annealing of 6xxx Al alloy. Based on the calculated diagrams, the design strategy of 6xxx Al alloy to produce highest strength due to Mg2Si is discussed.

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

Directory of Open Access Journals (Sweden)

Andrea Školáková

2017-11-01

Full Text Available In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these alloys and very good values of mechanical properties. Alloying by chromium ensured the highest thermal stability, while nickel addition refined the structure of the consolidated alloy. High thermal stability of all tested alloys was described in context with the transformation of the quasicrystalline phases to other types of intermetallics.

Nanotwinned Ti(O,C) induced by oriented attachment in a hot-pressed Nb–Ti–Al alloy

International Nuclear Information System (INIS)

Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Jin, Tao; Sun, Xiaofeng; Zheng, Qi

2016-01-01

The microstructures and formation mechanisms of various kinds of Ti(O,C) twins in a Nb–23Ti–15Al alloy have been investigated. The crystallographic features of the twins are systematically characterized using transmission electron microscopy (TEM). Lamellar or corner Ti(O,C) twins consist of coherent {111} twin boundaries (TBs) and incoherent {112} TBs. The three-fold Ti(O,C) twins are newly found, with symmetric Σ9 {114} or asymmetric Σ9 {115}/{111} serving as the secondary TBs. Moreover, slabs on Ti(O,C) TBs showing three-layer periodic contrasts are identified to be the twin overlapping. According to the microstructure characteristics, we propose a new model based on oriented attachment to interpret the formation of Ti(O,C) twins, which involves the contact, rotation, attachment and Ostwald ripening of Ti(O,C) grains. Our results provide new insights on the formation mechanisms of nanotwinned grains.

Al-Li alloy 1441 for fuselage applications

Energy Technology Data Exchange (ETDEWEB)

Bird, R.K.; Dicus, D.L. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center; Fridlyander, J.N.; Sandler, V.S.

2000-07-01

A cooperative investigation was conducted to evaluate Al-Cu-Mg-Li alloy 1441 for long service life fuselage applications. Alloy 1441 is currently being used for fuselage applications on the Russian Be- 103 amphibious aircraft, and is expected to be used for fuselage skin on a new Tupolev business class aircraft. Alloy 1441 is cold-rollable and has several attributes that make it attractive for fuselage skin applications. These attributes include lower density and higher specific modulus with similar strength as compared to conventional Al-Cu-Mg alloys. Cold-rolled 1441 Al-Li sheet specimens were tested at NASA Langley research center (LaRC) and at the All-Russia Institute of Aviation Materials (VIAM) in Russia to evaluate tensile properties, fracture toughness, impact resistance, fatigue life and fatigue crack growth rate. In addition, fuselage panels were fabricated by Tupolev Design Bureau (TDB) using 1441 skins and Al-Zn-Mg-Cu alloy stiffeners. The panels were subjected to cyclic pressurization fatigue tests at TDB and at LaRC to simulate fuselage pressurization/depressurization during aircraft service. This paper discusses the results from this investigation. (orig.)

Grain size and temperature influence on the toughness of a CuAlBe shape memory alloy

International Nuclear Information System (INIS)

Albuquerque, Victor Hugo C. de; Melo, Tadeu Antonio de A; Gomes, Rodinei M.; Lima, Severino Jackson G. de; Tavares, Joao Manuel R.S.

2010-01-01

Research highlights: → This work evaluated the capacity of a CuAlBe alloy to absorb energy until rupture. → The V-notch Charpy test was adopted at -150, -100, -50, 0, 50, 100 and 150 deg. C. → Charpy tests were complemented by DSC, DSC with optical microscope and by SEM. → First work to analyze the toughness of a CuAlBe alloy based on the Charpy test. → The results are of relevant value to enhance the understanding of the CuAlBe alloy. - Abstract: This work is a study of the influence of grain size and temperature on the toughness of CuAlBe shape memory alloys with (CuAlBeNbNi) and without NbNi (CuAlBe) grain refiner elements. The toughness analysis was based on the V-notch Charpy impact test under temperatures of -150, -100, -50, 0, 50, 100 and 150 deg. C. A statistical analysis of the results led to the conclusion that the toughness of both alloys was influenced by temperature and grain size. The CuAlBeNbNi alloy absorbed higher impact energy than the CuAlBe alloy showing that the refining elements improved the toughness of the alloy. To confirm and complement these findings, the fracture surfaces were evaluated by stereomicroscopy. Smooth homogeneous surfaces and rough heterogonous surfaces were detected for the CuAlBeNbNi and CuAlBe alloys, respectively. Predominately brittle zones were confirmed by scanning electron microscopy in both alloys. Furthermore, to determine the phase transformation temperatures and the associated microstructures, the alloys were assessed by conventional differential scanning calorimetry (DSC) and DSC with optical microscopy.

Grain size and temperature influence on the toughness of a CuAlBe shape memory alloy

Energy Technology Data Exchange (ETDEWEB)

Albuquerque, Victor Hugo C. de, E-mail: victor.albuquerque@fe.up.pt [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Melo, Tadeu Antonio de A, E-mail: tadeu@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Gomes, Rodinei M., E-mail: gomes@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Lima, Severino Jackson G. de, E-mail: jackson@lsr.ct.ufpb.br [Universidade Federal da Paraiba (UFPB), Departamento de Engenharia Mecanica (DEM), Laboratorio de Solidificacao Rapida LSR, Cidade Universitaria, S/N 58059-900 Joao Pessoa, PB (Brazil); Tavares, Joao Manuel R.S., E-mail: tavares@fe.up.pt [Faculdade de Engenharia da Universidade do Porto (FEUP), Departamento de Engenharia Mecanica (DEMec)/Instituto de Engenharia Mecanica e Gestao Industrial INEGI, Rua Dr. Roberto Frias, S/N 4200-465 Porto (Portugal)

2010-11-25

Research highlights: {yields} This work evaluated the capacity of a CuAlBe alloy to absorb energy until rupture. {yields} The V-notch Charpy test was adopted at -150, -100, -50, 0, 50, 100 and 150 deg. C. {yields} Charpy tests were complemented by DSC, DSC with optical microscope and by SEM. {yields} First work to analyze the toughness of a CuAlBe alloy based on the Charpy test. {yields} The results are of relevant value to enhance the understanding of the CuAlBe alloy. - Abstract: This work is a study of the influence of grain size and temperature on the toughness of CuAlBe shape memory alloys with (CuAlBeNbNi) and without NbNi (CuAlBe) grain refiner elements. The toughness analysis was based on the V-notch Charpy impact test under temperatures of -150, -100, -50, 0, 50, 100 and 150 deg. C. A statistical analysis of the results led to the conclusion that the toughness of both alloys was influenced by temperature and grain size. The CuAlBeNbNi alloy absorbed higher impact energy than the CuAlBe alloy showing that the refining elements improved the toughness of the alloy. To confirm and complement these findings, the fracture surfaces were evaluated by stereomicroscopy. Smooth homogeneous surfaces and rough heterogonous surfaces were detected for the CuAlBeNbNi and CuAlBe alloys, respectively. Predominately brittle zones were confirmed by scanning electron microscopy in both alloys. Furthermore, to determine the phase transformation temperatures and the associated microstructures, the alloys were assessed by conventional differential scanning calorimetry (DSC) and DSC with optical microscopy.

The formation of AlB2 in an Al-B master alloy

International Nuclear Information System (INIS)

Wang Xiaoming

2005-01-01

The formation of borides in an Al-3 wt.%B master alloy, produced via chemical reactions of KBF 4 and aluminium has been investigated. The chemical reactions produce boron, which dissolves into molten aluminium and subsequently forms aluminium borides. Backscattered electron imaging (BEI) of the Al-3 wt.%B master alloy under a scanning electron microscope (SEM) revealed the presence of two types of phases that contain different levels of boron. Combined with X-ray diffraction (XRD) results, the two types of phases are identified as AlB 2 on AlB 12 . This gives a direct evidence for a peritectic reaction of AlB 12 and aluminium, which produces AlB 2 . The thermodynamic properties of the reactions that may be involved are examined, and the presence of AlB 12 phase in the master alloy explained. The observed microstructure is explained according to the peritectic reaction in an Al-B phase diagram. The stability of AlB 2 and AlB 12 at lower temperature than 975 deg. C is clarified

Correlative Microscopy of Alpha Prime Precipitation in Neutron-Irradiated Fe-Cr-Al Alloys

Energy Technology Data Exchange (ETDEWEB)

Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States)

2016-12-01

Fe-Cr-Al alloys are currently being considered for accident tolerant light water reactor fuel cladding applications due to their superior high temperature oxidation and corrosion resistance compared to Zr-based alloys. This work represents the current state-of-the-art on both techniques for analysis of α' precipitate microstructures and the processes and mechanisms governing its formation in neutron-irradiated Fe-Cr-Al alloys.

Fabrication of Intermetallic Titanium Alloy Based on Ti2AlNb by Rapid Quenching of Melt

Science.gov (United States)

Senkevich, K. S.; Serov, M. M.; Umarova, O. Z.

2017-11-01

The possibility of fabrication of rapidly quenched fibers from alloy Ti - 22Al - 27Nb by extracting a hanging melt drop is studied. The special features of the production of electrodes for spraying the fibers by sintering mechanically alloyed powdered components of the alloy, i.e., titanium hydride, niobium, and aluminum dust, are studied. The rapidly quenched fibers with homogeneous phase composition and fine-grained structure produced from alloy Ti - 22Al - 27Nb are suitable for manufacturing compact semiproducts by hot pressing.

Grain refining efficiency of Al-Ti-C alloys

International Nuclear Information System (INIS)

Birol, Yuecel

2006-01-01

The problems associated with boride agglomeration and the poisoning effect of Zr in Zr-bearing alloys have created a big demand for boron-free grain refiners. The potential benefits of TiC as a direct nucleant for aluminium grains have thus generated a great deal of interest in TiC-bearing alloys in recent years. In Al-Ti-C grain refiners commercially available today, Al 3 Ti particles are introduced into the melt along with the TiC particles. Since the latter are claimed to nucleate α-Al directly, it is of great technological interest to see if reducing the Ti:C ratio further, i.e., increasing the C content of the grain refiner, will produce an increase in the grain refining efficiency of these alloys. A series of grain refiner samples with the Ti concentration fixed at 3% and a range of C contents between 0 and 0.75 were obtained by appropriately mixing an experimental Al-3Ti-0.75C alloy with Al-10Ti alloy and commercial purity aluminium. The grain refining efficiency of these grain refiners was assessed to investigate the role of the insoluble TiC and the soluble Al 3 Ti particles. The optimum chemistry for the Al-Ti-C grain refiners was also identified

Grain refining efficiency of Al-Ti-C alloys

Energy Technology Data Exchange (ETDEWEB)

Birol, Yuecel [Materials Institute, Marmara Research Center, TUBITAK, 41470 Gebze, Kocaeli (Turkey)]. E-mail: yucel.birol@mam.gov.tr

2006-09-28

The problems associated with boride agglomeration and the poisoning effect of Zr in Zr-bearing alloys have created a big demand for boron-free grain refiners. The potential benefits of TiC as a direct nucleant for aluminium grains have thus generated a great deal of interest in TiC-bearing alloys in recent years. In Al-Ti-C grain refiners commercially available today, Al{sub 3}Ti particles are introduced into the melt along with the TiC particles. Since the latter are claimed to nucleate {alpha}-Al directly, it is of great technological interest to see if reducing the Ti:C ratio further, i.e., increasing the C content of the grain refiner, will produce an increase in the grain refining efficiency of these alloys. A series of grain refiner samples with the Ti concentration fixed at 3% and a range of C contents between 0 and 0.75 were obtained by appropriately mixing an experimental Al-3Ti-0.75C alloy with Al-10Ti alloy and commercial purity aluminium. The grain refining efficiency of these grain refiners was assessed to investigate the role of the insoluble TiC and the soluble Al{sub 3}Ti particles. The optimum chemistry for the Al-Ti-C grain refiners was also identified.

Mechanical properties of Al-Cu alloy-SiC composites

Science.gov (United States)

Anggara, B. S.; Handoko, E.; Soegijono, B.

2014-09-01

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

Mechanical properties of Al-Cu alloy-SiC composites

Energy Technology Data Exchange (ETDEWEB)

Anggara, B. S., E-mail: anggorobs1960@yahoo.com [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, Indonesia 13220 and PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia); Handoko, E. [Jurusan Fisika, FMIPA Universitas Negeri Jakarta, 13220 (Indonesia); Soegijono, B. [PPS Ilmu Material, Department Fisika, FMIPA, Universitas Indonesia (Indonesia)

2014-09-25

The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

International Nuclear Information System (INIS)

Groebner, J.; Rokhlin, L.L.; Dobatkina, T.V.; Schmid-Fetzer, R.

2007-01-01

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges

Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

Energy Technology Data Exchange (ETDEWEB)

Groebner, J. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany); Rokhlin, L.L. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Dobatkina, T.V. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Schmid-Fetzer, R. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

2007-05-16

Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges.

Divorced Eutectic Solidification of Mg-Al Alloys

Science.gov (United States)

Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo

2015-08-01

We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed -Mg phase followed by the nucleation of the -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.

Corrosion of Zn5Al and Zn55Al alloys with cerium, praseodymium and neodymium

International Nuclear Information System (INIS)

Alikhanova, S.D.

2017-01-01

The present work is devoted to corrosion of Zn5Al and Zn55Al alloys with cerium, praseodymium and neodymium. The purpose of present work is elaboration of optimal composition of zinc-aluminium alloys Zn5Al and Zn55Al alloyed by rare-earth metals of cerium subgroup which are used as anode covers for protection of steel from corrosion. Therefore, the regularities of change of corrosion-electrochemical properties in various corrosive mediums have been determined; processes mechanisms of high temperature oxidation of alloys in solid state have been studied; in the products of alloys oxidation their phase components have been defined and their role in the corrosion process have been revealed; the optimal compositions of zinc-aluminium alloys alloyed by rare earth metals, which are protected by two patents of the Republic of Tajikistan have been elaborated.

Structure and mechanical properties of Al-3Fe rapidly solidified alloy

International Nuclear Information System (INIS)

Karakoese, Ercan; Keskin, Mustafa

2011-01-01

The Al based Al-3 wt%Fe alloy was prepared by conventionally casting (ingot) and further processed the melt-spinning technique and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) together with energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC) and the Vickers microhardness tester. The rapidly solidified (RS) binary alloys were composed of supersaturated α-Al solid solution and finely dispersed intermetallic phases. Experimental results showed that the mechanical properties of RS alloys were enhanced, which can be attributed to significant changes in the microstructure. The dependence of microhardness H V on the solidification rate (V) was analysed. These results showed that with the increasing values of V, the values of H V increased.

Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

Energy Technology Data Exchange (ETDEWEB)

Kad, B.K.

1999-07-01

A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

Solidification processing of intermetallic Nb-Al alloys

Science.gov (United States)

Smith, Preston P.; Oliver, Ben F.; Noebe, Ronald D.

1992-01-01

Several Nb-Al alloys, including single-phase NbAl3 and the eutectic of Nb2Al and NbAl3, were prepared either by nonconsumable arc melting in Ar or by zone processing in He following initial induction melting and rod casting, and the effect of the solidification route on the microstructure and room-temperature mechanical properties of these alloys was investigated. Automated control procedures and melt conditions for directional solidification of NbAl3 and the Nb2Al/Nb3Al eutectic were developed; high purity and stoichiometry were obtained. The effects of ternary additions of Ti and Ni are described.

Synthesis of Nb-18%Al alloy by mechanical alloying method

International Nuclear Information System (INIS)

Dymek, S.; Wrobel, M.; Dollar, M.

1999-01-01

The main goal of this study was attempt to employ by mechanical alloying to produce Nb-Al alloy. The Nb-rich alloy composition was selected in order to receive the ductile niobium solid solution (Nb ss ) phase in the final, equilibrium state. This ductile phase was believed to prevent crack propagation in the consolidated alloy and thus to improve its ductility and toughness. Elemental powders of niobium (99.8% pure and -325 mesh) and aluminium (99.9% pure and -325 mesh) were used as starting materials. These powders were mixed to give the nominal compositions od 82% Nb and 18% Al (atomic percent). Mechanical alloying was carried out in a Szegvari laboratory attritor mill in an argon atmosphere with the controlled oxygen level reduced to less than 10 ppm. The total milling time was 86 hours. During the course of milling powder samples were taken out after 5, 10 and 20 hours, which allowed characterization of the powder morphology and progress of the mechanical alloying process. The changes in particle morphology during milling were examined using a scanning electron microscope and the phase analysis was performed in a X-ray diffractometer with CoK α radiation. Initially, particles' size increased and their appearance changed from the regular to one of the flaky shape. X-ray diffraction patterns of examined powders as a function of milling time are presented. Peaks from Al, through much weaker than in the starting material, were still present after 5 hours of milling but disappeared completely after 10 hours of milling. With increasing milling time, the peaks became broader and their intensities decreased. Formation of amorphous phase was observed after 86 hours of milling. This was deducted from a diffuse halo observed at the 2Θ angle of about 27 o . Intermetallic phases Nb 3 Al and Nb 2 Al were found in the consolidated material only. (author)

Hydrogen permeation in FeCrAl alloys for LWR cladding application

Science.gov (United States)

Hu, Xunxiang; Terrani, Kurt A.; Wirth, Brian D.; Snead, Lance L.

2015-06-01

FeCrAl, an advanced oxidation-resistant iron-based alloy class, is a highly prevalent candidate as an accident-tolerant fuel cladding material. Compared with traditional zirconium alloy fuel cladding, increased tritium permeation through FeCrAl fuel cladding to the primary coolant is expected, raising potential safety concerns. In this study, the hydrogen permeability of several FeCrAl alloys was obtained using a static permeation test station, which was calibrated and validated using 304 stainless steel. The high hydrogen permeability of FeCrAl alloys leads to concerns with respect to potentially significant tritium release when used for fuel cladding in LWRs. The total tritium inventory inside the primary coolant of a light water reactor was quantified by applying a 1-dimensional steady state tritium diffusion model to demonstrate the dependence of tritium inventory on fuel cladding type. Furthermore, potential mitigation strategies for tritium release from FeCrAl fuel cladding were discussed and indicate the potential for application of an alumina layer on the inner clad surface to serve as a tritium barrier. More effort is required to develop a robust, economical mitigation strategy for tritium permeation in reactors using FeCrAl clad fuel assemblies.

Reinforcement of the concrete base slab of the ATLAS cavern

CERN Multimedia

Maximilien Brice

2002-01-01

Photo 02: UX15 cavern, preparation for concreting of base slab first lift. Photo 05: UX15 cavern, placing of reinforcement for base slab first lift. Photo 07: UX15 cavern, preparation for concreting of base slab first lift. Photo 09: UX15 cavern, placing of reinforcement for base slab first lift. Photo 10: UX15 cavern, view into PX14 shaft above. Photo 12: UX15 cavern, temporary access platform of RB16 tunnel. Photo 15: UJ17 chamber, invert excavation.

Creep properties and precipitate evolution in Al-Li alloys microalloyed with Sc and Yb

Energy Technology Data Exchange (ETDEWEB)

Krug, Matthew E. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208 (United States); Seidman, David N. [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208 (United States); Northwestern Center for Atom Probe Tomography, Northwestern University, 2220 Campus Drive, Evanston, IL 60208 (United States); Dunand, David C., E-mail: dunand@northwestern.edu [Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL 60208 (United States)

2012-07-30

Highlights: Black-Right-Pointing-Pointer We examine the creep behavior of Al-alloys with Li and rare earth element additions. Black-Right-Pointing-Pointer These alloys exhibit threshold stresses below which no measurable creep occurs. Black-Right-Pointing-Pointer Larger precipitate size and lattice parameter mismatch increase creep resistance. Black-Right-Pointing-Pointer A simple parameter describes the threshold stress behavior in ternary Al-Sc-X alloys. Black-Right-Pointing-Pointer The findings are explained by a recent model of dislocation-precipitate interactions. - Abstract: A dilute Al-Sc alloy (Al-0.12 Sc, at.%, Al-Sc), its counterpart with a Li addition (Al-2.9 Li-0.11 Sc, at.%, Al-Li-Sc), as well as a quaternary alloy (Al-5.53 Li-0.048 Sc-0.009 Yb, at.%, Al-Li-Sc-Yb) were isothermally aged at 325 Degree-Sign C, and in some cases isochronally aged to 450 Degree-Sign C. As the {alpha} Prime -Al{sub 3}(Li,Sc) and Al{sub 3}(Li,Sc,Yb) precipitates, with L1{sub 2} structure, coarsen in the two Li-containing alloys, their Li and Yb concentrations decrease and their Sc concentration increases. A significant interfacial excess of Li also segregates at the {alpha}-Al matrix/{alpha} Prime -Al{sub 3}Sc(Li,Sc,Yb) precipitate interface: 5.99 {+-} 0.05 atoms nm{sup -2} in Al-Li-Sc and 13.2 {+-} 0.4 atoms nm{sup -2} in Al-Li-Sc-Yb after aging isochronally to 450 Degree-Sign C. During compression creep at 300 Degree-Sign C, the aged alloys exhibit threshold stresses between 8 and 22 MPa. A recent threshold stress model based on elastic interactions between dislocations and precipitates predicts correctly that Li additions in the Al-Li-Sc alloy reduce the threshold stress, while Yb in the Al-Li-Sc-Yb alloy increases it. The model is also in agreement with the threshold stresses of all Al-Sc-X alloys published to date.

Hot Deformation Behavior and Pulse Current Auxiliary Isothermal Forging of Hot Pressing Sintering TiAl Based Alloys.

Science.gov (United States)

Shi, Chengcheng; Jiang, Shaosong; Zhang, Kaifeng

2017-12-16

This paper focuses on the fabrication of as-forged Ti46.5Al2Cr1.8Nb-(W, B) alloy via pulse current auxiliary isothermal forging (PCIF). The starting material composed of near gamma (NG) microstructure was fabricated by adopting pre-alloyed powders via hot pressing sintering (HPS) at 1300 °C. Isothermal compression tests were conducted at a strain rate range of 0.001-0.1 s -1 and a temperature range of 1125-1275 °C to establish the constitutive model and processing map. The optimal hot deformation parameters were successfully determined (in a strain rate range of 10 -3 -2.5 × 10 -3 s -1 and temperature range of 1130-1180 °C) based on the hot processing map and microstructure observation. Accordingly, an as-forged TiAl based alloy without cracks was successfully fabricated by PCIF processing at 1175 °C with a nominal strain rate of 10 -3 s -1 . Microstructure observation indicated that complete dynamic recrystallization (DRX) and phase transformation of γ→α₂ occurred during the PCIF process. The elongation of as-forged alloy was 136%, possessing a good secondary hot workability, while the sintered alloy was only 66% when tested at 900 °C with a strain rate of 2 × 10 -4 s -1 .

Investigation of as-cast alloys in the Pt-Al-Cr system

International Nuclear Information System (INIS)

Suess, R.; Cornish, L.A.; Witcomb, M.J.

2010-01-01

Platinum-based alloys are being developed which have microstructures that are analogous to the γ/γ' microstructure of the nickel-based superalloys. These Pt-based alloys have the potential to be used for high-temperature applications. The ternary Pt-Al-Cr system was investigated as part of the continued development of a thermodynamic database for the Pt-Al-Cr-Ru system. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses were used to obtain phase equilibria data. The alloys were studied in the as-cast condition. A solidification projection was constructed and a liquidus surface derived. It was concluded that all phase regions were identified correctly since the results were self-consistent. Three ternary phases and 21 ternary invariant reactions were identified.

Effects of Al content on structure and mechanical properties of hot-rolled ZrTiAlV alloys

International Nuclear Information System (INIS)

Liang, S.X.; Yin, L.X.; Che, H.W.; Jing, R.; Zhou, Y.K.; Ma, M.Z.; Liu, R.P.

2013-01-01

Highlights: • Phase structure is greatly dependent on the Al content. • Intermetallic compound will precipitates while Al content is over 6.9 wt%. • Equiaxed α-phase grains present in the hot-rolled alloy with 6.9 wt% Al. • Alloys with Al content from 3.3 wt% to 5.6 wt% have good mechanical properties. - Abstract: Zirconium alloys show attractive properties for astronautic applications where the most important factors are anti-irradiation, corrosion resistance, anti-oxidant, very good strength-to-weight ratio. The effects of Al content (2.2–6.9 wt%) on structure and mechanical properties of the hot-rolled ZrTiAlV alloy samples were investigated in this study. Each sample of the hot-rolled ZrTiAlV alloys with Al contents from 2.2 wt% to 5.6 wt% is composed of the α phase and β phase, meanwhile, the relative content of the α phase increased with the Al content. However, the (ZrTi) 3 Al intermetallic compound was observed as the Al content increased to 6.9 wt%. Changes of phase compositions and structure with Al content distinctly affected mechanical properties of ZrTiAlV alloys. Yield strength of the alloy with 2.2 wt% Al is below 200 MPa. As Al content increased to 5.6 wt%, the yield strength, tensile strength and elongation of the examined alloy are 1088 MPa, 1256 MPa and 8%, respectively. As Al content further increased to 6.9 wt%, a rapid decrease in ductility was observed as soon as the (ZrTi) 3 Al intermetallic compound precipitated. Results show that the ZrTiAlV alloys with Al contents between 3.3 wt% and 5.6 wt% have excellent mechanical properties

Grain refinement of AZ91D magnesium alloy by a new Mg–50%Al4C3 master alloy

International Nuclear Information System (INIS)

Liu, Shengfa; Chen, Yang; Han, Hui

2015-01-01

A novel and simple method for preparing Mg–50%Al 4 C 3 (hereafter in wt.%) master alloy has been developed by powder in-situ synthesis process under argon atmosphere. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) results show the existence of Al 4 C 3 particles in this master alloy. After adding 1.8% Mg–50%Al 4 C 3 master alloy, the average grain size of α-Mg decreased from 360 μm to 154 μm. Based on the DTA test results and calculation of the planar disregistry between Al 4 C 3 and α-Mg, Al 4 C 3 particles located in the central regions of magnesium grains can act as the heterogeneous nucleus of primary α-Mg phase

First-principles study of L10 Ti-Al and V-Al alloys

International Nuclear Information System (INIS)

Chubb, S.R.; Papaconstantopoulos, D.A.; Klein, B.M.

1988-01-01

As a first step towards understanding the reduced embrittlement of L1 0 Ti-Al alloys which accompanies the introduction of small concentrations of V, we have determined from first principles, using full-potential linearized--augmented-plane-wave calculations, the equilibrium values of the structural parameters and the associated electronic structure for the stoichiometric (L1 0 ) Ti-Al (tetragonal) compound. Our calculated values of c/a and a are in good agreement with experiment. Using the same method of calculation, we have also studied the electronic structure associated with the (hypothetical) L1 0 V-Al alloy that would form when V is substituted for Ti. We find that (1) the electronic structures of these V-Al alloys are relatively insensitive to variations of c/a and a; (2) near the Ti-Al equilibrium geometry, the electronic structures of the V-Al and Ti-Al alloys are very similar; and (3) that a rigid-band model involving substitution of V for Ti can be used to gain a qualitative understanding of the reduction in c/a which accompanies the introduction of small concentrations of V. We relate the reduction in c/a to important changes in the bonding that accompany the occupation of bands immediately above the Fermi level of the stoichiometric Ti-Al compound

Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

Energy Technology Data Exchange (ETDEWEB)

Plevachuk, Yu. [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Metal Physics; Egry, I.; Brillo, J.; Holland-Moritz, D. [Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. fuer Raumsimulation; Kaban, I. [Chemnitz Univ. of Technolgy (Germany). Inst. of Physics

2007-02-15

The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a noncontact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al-Fe and Al-Ni alloys. (orig.)

Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by MgGa δ doping in (AlN)m/(GaN)n superlattice

Science.gov (United States)

Wang, Xiao; Wang, Wei; Wang, Jingli; Wu, Hao; Liu, Chang

2017-03-01

P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)5/(GaN)1 superlattice (SL) in Al0.83Ga0.17N disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as MgGa δ doped AlGaN SLs. Mg acceptor activation energy was significantly reduced from 0.378 to 0.331 eV by using MgGa δ doping in SLs instead of traditional doping in alloys. This new process was confirmed to be able to realize high p-type doping in high Al-content AlGaN.

Grain refining of Al-4.5Cu alloy by adding an Al-30TiC master alloy

Energy Technology Data Exchange (ETDEWEB)

Sato, Kazuaki [Toyota Motor Corp., Shizuoka (Japan). Materials Engineering Div. III; Flemings, M.C. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering

1998-06-01

A particulate Al-30 wt pct TiC composite was employed as a grain refiner for the Al-4.5 wt pct Cu alloy. The composite contains submicron TiC particles. The addition of the TiC grain refiner to the metal alloy in the amount of 0.1 Ti wt pct effected a remarkable reduction in the average grain size in Al-4.5 wt pct Cu alloy castings. With the content of over 0.2 Ti wt pct, the grain refiner maintained its refining effectiveness even after a 3,600-second holding time at 973 K. The TiC particles in the resulting castings were free of interfacial phases. It is concluded that the TiC are the nucleating agents and that they are resistant to the fading effect encountered with most grain refiners.

Synthesis Of NiCrAlC alloys by mechanical alloying; Sintese de ligas NiCrAlC por moagem de alta energia

Energy Technology Data Exchange (ETDEWEB)

Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M., E-mail: alissonkws@gmail.co [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil)

2010-07-01

The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni{sub 3}Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

A new technique to modify hypereutectic Al-24%Si alloys by a Si-P master alloy

Energy Technology Data Exchange (ETDEWEB)

Wu Yaping; Wang Shujun; Li Hui [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, 73 Jingshi Road, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

2009-05-27

The modification effect of a Si-P master alloy on Al-24%Si alloy was investigated by using electron probe micro-analyzer (EPMA) and optical microscopy (OM). The dissolution problem of the Si-P master alloys was solved by changing the sequence of addition. When the Si-P master alloy was added into Al melt before the addition of silicon, the best modification effect could be achieved. The modification parameters of the master alloy on Al-24%Si alloy were optimized through designing and analyzing the orthogonal experiment, and their influences on the modification effect were discussed. The results show that the influence of temperature on the modification effect is the greatest, followed by the addition level, and the holding time is the least. The optimized modification parameters are the modification temperature of 810 deg. C, the addition level of 0.35 wt.%, the holding time of 30 min + 50 min whose meaning is that the Si-P master alloy is added firstly to the molten Al, and silicon is added 30 min later, then holding another 50 min. In addition, the modification mechanism of the Si-P master alloy on Al-24%Si alloy was also discussed.

Electrochemical corrosion behavior of Ni-containing hypoeutectic Al-Si alloy

Directory of Open Access Journals (Sweden)

Abul Hossain

2015-12-01

Full Text Available Electrochemical corrosion characteristics of the thermally treated 2 wt % Ni-containing Al-6Si-0.5Mg alloy were studied in NaCl solutions. The corrosion behavior of thermally treated (T6 Al-6Si-0.5Mg (-2Ni alloys in 0.1 M NaCl solution was investigated by electrochemical potentiodynamic polarization technique consisting of linear polarization method using the fit of Tafel plot and electrochemical impedance spectroscopy (EIS techniques. Generally, linear polarization experiments revealed a decrease of the corrosion rate at thermal treated Al-6Si-0.5Mg-2Ni alloy. The EIS test results showed that there is no significant change in charge transfer resistance (Rct after addition of Ni to Al-6Si-0.5Mg alloy. The magnitude of the positive shift in the open circuit potential (OCP, corrosion potential (Ecorr and pitting corrosion potential (Epit increased with the addition of Ni to Al-6Si-0.5Mg alloy. The forms of corrosion in the studied Al-6Si-0.5Mg alloy (except Al-6Si-0.5Mg-2Ni alloy are pitting corrosion as obtained from the scanning electron microscopy (SEM study.

Fabrication and mechanical behavior of bulk nanoporous Cu via chemical de-alloying of Cu–Al alloys

Energy Technology Data Exchange (ETDEWEB)

Chen, Fei, E-mail: chenfei027@gmail.com [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Chen, Xi; Zou, Lijie; Yao, Yao; Lin, Yaojun; Shen, Qiang [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Lavernia, Enrique J. [Department of Chemical Engineering and Materials Science, University of California at Irvine, Irvine, CA 92697 (United States); Zhang, Lianmeng, E-mail: lmzhang@whut.edu.cn [State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2016-04-13

We report on a study of the influence of microstructure on the mechanical behavior of bulk nanoporous Cu fabricated by chemical de-alloying of Cu{sub 50}Al{sub 50}, Cu{sub 40}Al{sub 60}, Cu{sub 33}Al{sub 67} and Cu{sub 30}Al{sub 70} (at%) alloys. The precursor Cu–Al alloys were fabricated using arc melting and bulk nanoporous Cu was obtained by subsequent de-alloying of Cu–Al alloys in 20 wt% NaOH aqueous solution at a temperature of 65 °C. We studied the microstructure of the precursor Cu–Al alloys, as well as that of the as de-alloyed bulk nanoporous Cu, using X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry. Moreover, the compressive strength of bulk nanoporous Cu was measured and the relationship between microstructure and mechanical properties was studied. Our results show that the microstructure of bulk nanoporous Cu is characterized by bi-continuous interpenetrating ligament-channels with a ligament size of 130±20 nm (for Cu{sub 50}Al{sub 50}), 170±20 nm (for Cu{sub 40}Al{sub 60}) and 160±10 nm (for Cu{sub 33}Al{sub 67}). Interestingly the microstructure of de-alloyed Cu{sub 30}Al{sub 70} is bimodal with nanopores (100's nm) and interspersed featureless regions a few microns in size. The compressive strength increased with decreasing volume fraction of porosity; as porosity increased 56.3±2% to 73.9±2%, the compressive strength decreased from 17.18±1 MPa to 2.71±0.5 MPa.

Effect of alloying elements on martensitic transformation in the binary NiAl(β) phase alloys

International Nuclear Information System (INIS)

Kainuma, R.; Ohtani, H.; Ishida, K.

1996-01-01

The characteristics of the B2(β) to L1 0 (β') martensitic transformation in NiAl base alloys containing a small amount of third elements have been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). It is found that in addition to the normal L1 0 (3R) martensite, the 7R martensite is also present in the ternary alloys containing Ti, Mo, Ag, Ta, or Zr. While the addition of third elements X (X: Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Ta, W, and Si) to the binary Ni 64 Al 36 alloy stabilizes the parent β phase, thereby lowering the M s temperature, addition of third elements such as Co, Cu, or Ag destabilizes the β phase, increasing the M s temperature. The occurrence of the 7R martensite structure is attributed to solid solution hardening arising from the difference in atomic size between Ni and Al and the third elements added. The variation in M s temperature with third element additions is primarily ascribed to the difference in lattice stabilities of the bcc and fcc phases of the alloying elements

Coupled growth of Al-Al2Cu eutectics in Al-Cu-Ag alloys

International Nuclear Information System (INIS)

Hecht, U; Witusiewicz, V; Drevermann, A

2012-01-01

Coupled eutectic growth of Al and Al 2 Cu was investigated in univariant Al-Cu-Ag alloys during solidification with planar and cellular morphology. Experiments reveal the dynamic selection of small spacings, below the minimum undercooling spacing and show that distinct morphological features pertain to nearly isotropic or anisotropic Al-Al 2 Cu interfaces.

Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

International Nuclear Information System (INIS)

Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei

2017-01-01

Highlights: • Zn-Al LDHs film loaded nitrate anions has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method. • The Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs film were obtained based on anion-exchange mechanism. • The Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs film could effectively protect magnesium alloy. - Abstract: Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO_3 LDHs, Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VO_x LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

Design and fabrication of enhanced corrosion resistance Zn-Al layered double hydroxides films based anion-exchange mechanism on magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Zhou, Meng; Yan, Luchun; Ling, Hao; Diao, Yupeng; Pang, Xiaolu; Wang, Yanlin; Gao, Kewei, E-mail: kwgao@yahoo.com

2017-05-15

Highlights: • Zn-Al LDHs film loaded nitrate anions has been fabricated on a magnesium alloy substrate via a facile hydrothermal crystallization method. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film were obtained based on anion-exchange mechanism. • The Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs film could effectively protect magnesium alloy. - Abstract: Layered double hydroxides (LDHs) with brucite-like layer structure and the facile exchangeability of intercalated anions had attracted tremendous interest in many fields because of their great importance for both fundamental studies and practical applications. Herein zinc-aluminum layered double hydroxides (Zn-Al LDHs) films intercalated with nitrate anions on the magnesium alloy substrate were designed and fabricated via a facile hydrothermal crystallization method. In order to obtain better corrosion resistance, chloride and vanadate anions were intercalated into the LDHs interlayers via the anion-exchange reaction. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were used to examine structure, composition and morphology of the Zn-Al-NO{sub 3} LDHs, Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films. The corrosion resistance of the Zn-Al LDHs with different anion films was estimated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurement. EIS and polarization curves measurements revealed that the magnesium alloy could be effectively protected by the Zn-Al-Cl LDHs and Zn-Al-VO{sub x} LDHs films due to the blocking effect of chloride anions and the control-release ability of vanadate anions.

Preparation, deformation, and failure of functional Al-Sn and Al-Sn-Pb nanocrystalline alloys

Science.gov (United States)

Noskova, N. I.; Vil'Danova, N. F.; Filippov, Yu. I.; Churbaev, R. V.; Pereturina, I. A.; Korshunov, L. G.; Korznikov, A. V.

2006-12-01

Changes in the structure, hardness, mechanical properties, and friction coefficient of Al-30% Sn, Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb (wt %) alloys subjected to severe plastic deformation by equal-channel angular pressing (with a force of 40 tonne) and by shear at a pressure of 5 GPa have been studied. The transition into the nanocrystalline state was shown to occur at different degrees of plastic deformation. The hardness exhibits nonmonotonic variations, namely, first it increases and subsequently decreases. The friction coefficient of the Al-30% Sn, Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb alloys quenched from the melt was found to be 0.33; the friction coefficients of these alloys in the submicrocrystalline state (after equal-channel angular pressing) equal 0.24, 0.32, and 0.35, respectively. The effect of disintegration into nano-sized powders was found to occur in the Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb alloys after severe plastic deformation to ɛ = 6.4 and subsequent short-time holding.

Low Cycle Mechanical and Fatigue Properties of AlZnMgCu Alloy

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Pysz S.

2016-03-01

Full Text Available The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075 was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.

The effect of zinc on the microstructure and phase transformations of casting Al-Cu alloys

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Manasijević Ivana I.

2016-01-01

Full Text Available Copper is one of the main alloying elements for aluminum casting alloys. As an alloying element, copper significantly increases the tensile strength and toughness of alloys based on aluminum. The copper content in the industrial casting aluminum alloys ranges from 3,5 to 11 wt.%. However, despite the positive effect on the mechanical properties, copper has a negative influence on the corrosion resistance of aluminum and its alloys. In order to further improve the properties of Al-Cu alloys they are additional alloyed with elements such as zinc, magnesium and others. In this work experimental and analytical examination of the impact of zinc on the microstructure and phase transformations of Al-Cu alloys was carried out. In order to determine the effect of the addition of zinc to the structure and phase transformations of Al-Cu alloys two alloys of Al-Cu-Zn system with selected compositions were prepared and then examined using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX. The experimental results were compared with the results of thermodynamic calculations of phase equilibria.

Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

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J.B. Ferguson

2016-02-01

Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

Effect of hot rolling on the microstructure and mechanical properties of Ti3Al based dual phase alloys

International Nuclear Information System (INIS)

Wu, J.; Zhang, L.; Hua, W.; Qiu, G.

1999-01-01

Development of α 2 -Ti 3 Al based dual phase alloys have shown some promising potentials in property improvement by introducing Ti 5 Si 3 silicide phase into the matrix via Si alloying. However, the presence of coarse network of Ti 5 Si 3 phase formed by eutectic reaction in the as-cast state also embrittles the alloy. Both hot rolling and powder metallurgy are considered to be the possible ways to refine the Ti 5 Si 3 phase in the matrix. Two Ti-Al-Si-Nb alloys whose Si contents are 2 and 5 at.% respectively were arc melted into ingots and then hot rolled to sheets in this investigation. Optical metallographic examination correlates the microstructures of the as-cast and as-rolled alloys with the different rolling amounts, showing that the coarse silicide network is broken into small particles after hot rolling. Mechanical property testing from room temperature to 800 C indicates that the strength and plastic elongation of the hot-rolled alloys are much higher than those of the as-cast ones. The data obtained in this investigation are comparable with those obtained in the P/M processed specimens. Fracture surfaces of the alloys are also examined

A computational study of low-head direct chill slab casting of aluminum alloy AA2024

Science.gov (United States)

Hasan, Mainul; Begum, Latifa

2016-04-01

The steady state casting of an industrial-sized AA2024 slab has been modeled for a vertical low-head direct chill caster. The previously verified 3-D CFD code is used to investigate the solidification phenomena of the said long-range alloy by varying the pouring temperature, casting speed and the metal-mold contact heat transfer coefficient from 654 to 702 °C, 60-180 mm/min, and 1.0-4.0 kW/(m2 K), respectively. The important predicted results are presented and thoroughly discussed.

Annex 5 - Fabrication of U-Al alloy; Prilog 5 - Dobijanje legure U-Al

Energy Technology Data Exchange (ETDEWEB)

Drobnjak, Dj; Lazarevic, Dj; Mihajlovic, A [Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1961-12-15

Alloy U-Al with low content of aluminium is often used for fabrication of fuel elements because it is stable under moderate neutron flux density. Additionally this type of alloys show much better characteristics than pure uranium under reactor operating conditions (temperature, mechanical load, corrosion effect of water). This report contains the analysis of the phase diagram of U-Al alloy with low content of aluminium, applied procedure for alloying and casting with detailed description of equipment. Characteristics of the obtained alloy are described and conclusions about the experiment and procedure are presented. Sistem U-Al sa niskim sadrzajem aluminijuma jedan je od cesto koriscenih za izradu gorivnih elemenata, jer je dovoljno stabilan pri umerenim gustinama fluksa. Pored toga, u uslovima karakteristicnim za rad nuklearnog reaktora (temperatura, gradijent temperature, mehanicka naprezanja, koroziono dejstvo vode) legure ovog sistema pokazuju daleko bolja svojstva od nelegiranog urana. Referat sadrzi analizu dijagrama stanja U-Al legure sa niskim sadrzajem aluminijuma, primenjeni postupak legiranja i livenja sa opisom pojedinih uredjaja i operacija. Takodje su opisana svojstva dobijene legure i dat je zakljucak o eksperimentu i tehnici rada (author)

Braze Welding TIG of Titanium and Aluminium Alloy Type Al – Mg

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Winiowski A.

2016-03-01

Full Text Available The article presents the course and the results of technological tests related to TIG-based arc braze welding of titanium and AW-5754 (AlMg3 aluminium alloy. The tests involved the use of an aluminium filler metal (Al99.5 and two filler metals based on Al-Si alloys (AlSi5 and AlSi12. Braze welded joints underwent tensile tests, metallographic examinations using a light microscope as well as structural examinations involving the use of a scanning electron microscope and an X-ray energy dispersive spectrometer (EDS. The highest strength and quality of welds was obtained when the Al99.5 filler metal was used in a braze welding process. The tests enabled the development of the most convenient braze welding conditions and parameters.

Cu-segregation at the Q'/α-Al interface in Al-Mg-Si-Cu alloy

International Nuclear Information System (INIS)

Matsuda, Kenji; Teguri, Daisuke; Uetani, Yasuhiro; Sato, Tatsuo; Ikeno, Susumu

2002-01-01

Cu segregation was detected at the Q ' /α-Al interface in an Al-Mg-Si-Cu alloy by energy-filtered transmission electron microscopy. By contrast, in a Cu-free Al-Mg-Si alloy no segregation was observed at the interface between the matrix and Type-C precipitate

The development of platinum-based alloys and their thermodynamic database

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Cornish L.A.

2002-01-01

Full Text Available A series of quaternary platinum-based alloys have been demonstrated to exhibit the same two-phase structure as Ni-based superalloys and showed good mechanical properties. The properties of ternary alloys were a good indication that the quaternary alloys, with their better microstructure, will be even better. The quaternary alloy composition has been optimised at Pt84:Al11:Ru2:Cr3 for the best microstructure and hardness. Work has begun on establishing a thermodynamic database for Pt-Al-Ru-Cr alloys, and further work will be done to enhance the mechanical and oxidation properties of the alloys by adding small amounts of other elements to the base composition of Pt84:Al11:Ru2:Cr3.

Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

Science.gov (United States)

Apparao, K. Ch; Birru, Anil Kumar

2018-01-01

A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

Development of amorphous and nanocrystalline Al65Cu35-xZrx alloys by mechanical alloying

International Nuclear Information System (INIS)

Manna, I.; Chattopadhyay, P.P.; Banhart, F.; Fecht, H.J.

2004-01-01

Mechanical alloying of Al 65 Cu 35-x Zr x (x=5, 15 and 25 at.% Zr) elemental powder blends by planetary ball milling up to 50 h yields amorphous and/or nanocrystalline products. Microstructure of the milled product at different stages of milling has been characterized by X-ray diffraction, (XRD) high-resolution transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Among the different alloys synthesized by mechanical alloying, Al 65 Cu 20 Zr 15 yields a predominantly amorphous product, while the other two alloys develop a composite microstructure comprising nanocrystalline and amorphous solid solutions in Al 65 Cu 10 Zr 25 and nano-intermetallic phase/compound in Al 65 Cu 30 Zr 5 , respectively. The genesis of solid-state amorphization in Al 65 Cu 20 Zr 15 and Al 65 Cu 10 Zr 25 is investigated

Atomic bonding and mechanical properties of Al-Mg-Zr-Sc alloy

Institute of Scientific and Technical Information of China (English)

高英俊; 班冬梅; 韩永剑; 钟夏平; 刘慧

2004-01-01

The valence electron structures of Al-Mg alloy with minor Sc and Zr were calculated according to the empirical electron theory(EET) in solid. The results show that because of the strong interaction of Al atom with Zr and Sc atom in melting during solidification, the Al3 Sc and Al3 (Sc1-xZrx) particles which act as heterogeneous nuclear are firstly crystallized in alloy to make grains refine. In progress of solidification, the Al-Sc, Al-Zr-Sc segregation regions are formed in solid solution matrix of Al-Mg alloy owing to the strong interaction of Al atom with Zr, Scatoms in bulk of alloy, so in the following homogenization treatment, the finer dispersed Al3 Sc and Al3 (Sc1-x Zrx) second-particles which are coherence with the matrix are precipitated in the segregation region. These finer second particles with the strong Al-Zr, Al-Sc covalent bonds can strengthen the covalent bonds in matrix of the alloy, and also enhance the hardness and strength of Al-Mg alloy. Those finer second-particles precipitated in interface of sub-grains can also strengthen the covalence bonds there, and effectively hinder the interface of sub-grains from migrating and restrain the sub-grains from growing, and cause better thermal stability of Al-Mg alloy.

Development of powder metallurgy 2XXX series Al alloys for high temperature aircraft structural applications

Science.gov (United States)

Chellman, D. J.

1984-01-01

The objective of the present investigation was to improve the strength and fracture toughness combination of P/M 2124 Al alloys in accordance with NASA program goals for damage tolerance and fatigue resistance. Two (2) P/M compositions based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.12 and 0.60 wt. pct. Zr were selected for investigation. The rapid solidification rates produced by atomization were observed to prohibit the precipitation of coarse, primary Al3Zr in both alloys. A major portion of the Zr precipitated as finely distributed, coherent Al3Zr phases during vacuum preheating and solution heat treatment. The proper balance between Cu and Mg contents eliminated undissolved, soluble constituents such as Al2CuMg and Al2Cu during atomization. The resultant extruded microstructures produced a unique combination of strength and fracture toughness. An increase in the volume fraction of coherent Al3Zr, unlike incoherent Al20Cu2Mn3 dispersoids, strengthened the P/M Al base alloy either directly by dislocation-precipitate interactions, indirectly by a retardation of recrystallization, or a combination of both mechanisms. Furthermore, coherent Al3Zr does not appear to degrade toughness to the extent that incoherent Al20Cu2Mn3 does. Consequently, the addition of 0.60 wt. pct. Zr to the base alloy, incorporated with a 774K (935 F) solution heat treatment temperature, produces an alloy which exceeds all tensile property and fracture toughness goals for damage tolerant and fatigue resistant applications in the naturally aged condition.

Diffusion-induced quadrupole relaxation of 27Al nuclei in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at high temperatures

International Nuclear Information System (INIS)

Bottyan, L.; Beke, D.L.; Tompa, K.

1983-01-01

The temperature dependence of the laboratory frame spin-lattice relaxation time of 27 Al nuclei is measured in 5N Al and in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at 5.7 and 9.7 MHz resonance frequencies. The relaxation in pure aluminium is found to be purely due to the conduction electrons. An excess T 1 -relaxation contribution is detected in all Al-3d alloys investigated above 670 K. The excess relaxation rate is proportional to the impurity content and the temperature dependence of the excess contribution is of Arrhenius-type with an activation energy of (1.3 +- 0.3) eV for all of the investigated alloys. The relaxation contribution is found to be quadrupolar in origin and is caused by the relative diffusional jumps of solute atoms and Al atoms relatively far from the impurity. (author)

Development of an efficient grain refiner for Al-7Si alloy

Energy Technology Data Exchange (ETDEWEB)

Kori, S.A.; Murty, B.S.; Chakraborty, M. [Indian Inst. of Technol., Kharagpur (India). Dept. of Metall. and Mater. Eng.

2000-03-15

The response of Al-7Si alloy towards grain refinement by Al-Ti-B master alloys (with different Ti-B ratios) at different addition levels has been studied in detail. The results indicate that high B-containing master alloys are powerful grain refiners when compared to conventional grain refiners like Al-5Ti-lB master alloys. In the present study, indigenously developed master alloys have been used for the grain refinement of alloys Al-7Si and LM-25. Significant improvements in mechanical properties have been obtained with a combination of grain refiner and Sr as modifier. (orig.)

Age hardening in mechanically alloyed Al-Mg-Li-C-O

Energy Technology Data Exchange (ETDEWEB)

Papazian, J.M. (Corporate Research Center, Grumman Corporation, Bethpage, NY (USA)); Gilman, P. (Allied-Signal Inc., Morristown, NJ (USA))

1990-05-01

The age-hardening behavior of a series of mechanically alloyed Al-Mg-Li-C-O alloys containing 3.0-4.0 wt.% Mg and 1.3-1.75 wt.% Li was studied using hardness tests, differential scanning calorimetry (DSC) and transmission electron microscopy. The hardness tests showed an increased hardness after 100degC aging in all the alloys containing at least 1.5 at.% Li. Likewise, the calorimetry results showed the presence of pronounced precipitate dissolution peaks in these same alloys after 100degC aging. The volume fraction of precipitates formed (as measured by the dissolution enthalpies of the DSC peaks) increased systematically with increasing solute content. Transmission electron microscopy after 100 and 190degC aging showed images and diffraction spots similar to those of {delta}' (Al{sub 3}Li). Comparison of the DSC results with results from binary Al-Li and Al-Mg alloys indicated that the precipitates formed in the Al-Mg-Li-C-O alloys were similar to those formed in binary Al-Li alloys, and that the primary role of the magnesium was to lower the solid solubility of lithium. (orig.).

Microstructure and texture evolution in cryorolled Al 7075 alloy

International Nuclear Information System (INIS)

Jayaganthan, R.; Brokmeier, H.-G.; Schwebke, Bernd; Panigrahi, S.K.

2010-01-01

The present work investigates the microstructure and texture evolution of cryorolled Al 7075 alloy using FE-SEM, TEM, and neutron diffraction, respectively. The solution treated bulk Al 7075 alloy is subjected to rolling at liquid nitrogen temperature to produce sheets with different thickness reductions such as 35%, 50%, 70%, and 90%, respectively. It is evident from the microstructural characterisations of cryorolled samples that with the increasing deformation strain induced in the materials, the grains are fragmented and produce high amount of dislocation density due the suppression of dynamic recovery. The texture analysis of the cryorolled Al 7075 alloy has shown that the ideal fibres observed in the starting solution treated alloy has been destroyed during rolling. The Goss/Brass orientation of the cryorolled Al alloy is shifting towards the Brass components with increasing deformation strain induced in the samples. The orientation distribution functions of the cryorolled Al 7075 alloy clearly indicate the progressive weakening of the texture components, during cryorolling, with increasing strain, therefore, fragmentation and reorientation of micron sized grains occurs easily for the formation of subgrains and ultrafine-grained microstructures as evident from EBSD and TEM micrographs.

A new approach to grain refinement of an Mg-Li-Al cast alloy

International Nuclear Information System (INIS)

Jiang, B.; Qiu, D.; Zhang, M.-X.; Ding, P.D.; Gao, L.

2010-01-01

Crystallographic calculation based on the edge-to-edge matching model predicted that both TiB 2 and Al 3 Ti intermetallic compounds have strong potential to be effective grain refiners for β phase in the Mg-14Li-1Al alloy due to the small atomic matching misfit across the interface between the compounds and β phase. Experimental results showed that addition of 1.25 wt%Al-5Ti-1B master alloy reduced grain size of β phase in the alloy from 1750 to 500 μm. The possible grain refining mechanisms were also discussed.

Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

Energy Technology Data Exchange (ETDEWEB)

Kalay, Yunus Eren [Iowa State Univ., Ames, IA (United States)

2009-01-01

Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T₀ curves, which makes Al-Si a good candidate for solubility extension while the plunging T₀ line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

Tem Observation Of Precipitate Structures In Al-Zn-Mg Alloys With Additions Of Cu/Ag

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Watanabe K.

2015-06-01

Full Text Available Al-Zn-Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. In this work, three alloys, which were added Cu or Ag into the Al-Zn-Mg alloy, were prepared to compare the effect of the additional elements on the aging behavior. The content of Ag and Cu were 0.2at.% and the same as, respectively. Ag or Cu added alloy showed higher maximum hardness than base alloy. The particle shape and rod shape precipitates were observed in all alloys peak-aged at 423K. According to addition of Ag or Cu, the number density of the precipitates increased higher than that of base alloy.

Precipitation structures and mechanical properties of Al-Li-Zr alloy containing V

International Nuclear Information System (INIS)

Ying, J.K.; Ohashi, T.

1999-01-01

It is known that Al-Li alloys possess high elastic modulus and low density, and the metastable δ' (Al 3 Li) precipitate in these alloys affords considerable strengthening effect. However, with the strengthening resulting from the precipitation of δ' which is coherent with the matrix, these alloys suffer from low ductility and fracture toughness. It seems that the loss of ductility is the slip localization which occurs as a result of slip planes during deformation in connection with the specific hardening mechanism. As a result it indicates typical intergranular fracture. On the one hand, zirconium is used in many aluminum alloys to inhibit recrystallization during alloy processing. When zirconium is present in the alloy grain refinement occurs, which consequently, is considered as a factor that reduces the slip distance, and lowers the stress concentration across grain boundaries and at grain boundary triple points. Nevertheless, if only zirconium is added in Al-Li alloy it still shows intergranular fracture. By Zedaris et al., equilibrium phase Al 3 (Zr,V) in Al-Zr alloy containing V reduces the lattice mismatch along the c-axis with Al and, the L1 2 -structure metastable precipitates Al 3 (Zr,V) in Al-Zr-V alloys are stable at elevated temperature. Therefore, it is interesting to elucidate the effect of V in Al-Li-Zr alloy at the precipitation structures and mechanical properties of these alloys

Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

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Saleh A. Alkahtani

2016-01-01

Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

International Nuclear Information System (INIS)

Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

2007-01-01

Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

Science.gov (United States)

Lee, Jonathan A.

2009-01-01

In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

International Nuclear Information System (INIS)

Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

2016-01-01

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the Al

Effect of V or Zr addition on the mechanical properties of the mechanically alloyed Al-8wt%Ti alloys

International Nuclear Information System (INIS)

Moon, I.H.; Lee, J.H.; Lee, K.M.; Kim, Y.D.

1995-01-01

Mechanical alloying (MA) of Al-Ti alloy, being a solid state process, offers the unique advantage of producing homogeneous and fine dispersions of thermally stable Al 3 Ti phase, where the formation of the fine Al 3 Ti phase by the other method is restricted from the thermodynamic viewpoint. The MA Al-Ti alloys show substantially higher strength than the conventional Al alloys at the elevated temperature due to the presence of Al 3 Ti as well as Al 4 C 3 and Al 2 O 3 , of which the last two phases were introduced during MA process. The addition of V or Zr to Al-Ti alloy was known to decrease the lattice mismatch between the intermetallic compound and the aluminum matrix, and such decrease in lattice mismatching can influence positively the high temperature mechanical strength of the MA Al-Ti by increasing the resistance to dispersoid coarsening at the elevated temperature. In the present study, therefore, the mechanical behavior of the MA Al-Ti-V and Al-Ti-Zr alloys were investigated in order to evaluate the effect of V or Zr addition on the mechanical properties of the MA Al-8Ti alloy at high temperature

Study of polarization curves from AlSi12, AlSi5Mg and AlMg5 alloys due to corrosion problems in telecomunication equipment

International Nuclear Information System (INIS)

Silva, J.R.A. da

1984-01-01

The corrosion behaviour of three aluminium based alloys (AlSi 12, AlMg5 and AlSi 5Mg) when exposed to aqueous media containing chloride is investigated; these alloys are used in the manufacturing of telecomunication equipment. Accelerated corrosion testing and salt spray tests were carried out. The results include polarization curves obtained with three kinds of aqueous solutions (the first containing only 3% NaCl and the others, 3% NaCl and small amounts of Fe 3+ and Cu 2+ ions). (C.L.B.) [pt

Internal friction in Al alloys after neutron irradiation at low temperature

International Nuclear Information System (INIS)

Takamura, S.; Kobiyama, M.

1985-01-01

Internal friction and elastic modulus of dilute Al alloys have been measured after fast neutron irradiation at about 5 K. The internal friction spectra in Al-Pb, Al-Si, Al-Zn, Al-Ag, Al-Sn and Al-In are very similar. This result suggests that the configuration of the interstitial-solute atom complex in these alloys is very similar. In Al-Mg, the main complexes have the configuration with nearly symmetry, but its internal friction spectrum is different from that of the above-mentioned alloys. The internal friction spectra and their annealing behavior in Al-Be, Al-Mn, Al-Fe and Al-Cu demonstrate that the configuration of their interstitial-solute atom complex seems to be different from each other and the main complex in these alloys is immobile until stage III. (author)

Depth of array micro-holes with large aspect ratio in Al based cast alloy

Science.gov (United States)

Jin, Meiling; Qu, Yingdong; Li, Rongde

2018-03-01

In order to study on the depth of array micro-holes on Al base cast alloy, micro-hole with depth of 50 mm and diameter of 0.55 mm are successfully prepared by using poor wetting between carbon and Al. Accordingly, the mold of depth is established, the results show that calculated depth of micro-hole is 53.22 mm, relative error is 6% compare with the actual measured depth, and the depth of hole exponentially increases with the increasing of distance between two micro-holes. Surface tension and metallostatic pressure of metal molten are mainly affecting factors for depth of micro-holes.

Evolution of a novel Si-18Mn-16Ti-11P alloy in Al-Si melt and its influence on microstructure and properties of high-Si Al-Si alloy

Directory of Open Access Journals (Sweden)

Xiao-Lu Zhou

Full Text Available A novel Si-18Mn-16Ti-11P master alloy has been developed to refine primary Si to 14.7 ± 1.3 μm, distributed uniformly in Al-27Si alloy. Comparing with traditional Cu-14P and Al-3P, Si-18Mn-16Ti-11P provided a much better refining effect, with in-situ highly active AlP. The refined Al-27Si alloy exhibited a CTE of 16.25 × 10−6/K which is slightly higher than that of Sip/Al composites fabricated by spray deposition. The UTS and elongation of refined Al-27Si alloy were increased by 106% and 235% comparing with those of unrefined alloy. It indicates that the novel Si-18Mn-16Ti-11P alloy is more suitable for high-Si Al-Si alloys and may be a candidate for refining hypereutectic Al-Si alloy for electronic packaging applications. Moreover, studies showed that TiP is the only P-containing phase in Si-18Mn-16Ti-11P master alloy. A core-shell reaction model was established to reveal mechanism of the transformation of TiP to AlP in Al-Si melts. The transformation is a liquid-solid diffusion reaction driven by chemical potential difference and the reaction rate is controlled by diffusion. It means sufficient holding time is necessary for Si-18Mn-16Ti-11P master alloy to achieve better refining effect. Keywords: Hypereutectic Al-Si alloy, Primary Si, Refinement, AlP, Thermal expansion behavior, Si-18Mn-16Ti-11P master alloy

Method of mechanochemical synthesis for the production of nanocrystalline Nb-Al alloys

International Nuclear Information System (INIS)

Portnoj, V.K.; Tret'yakov, K.V.; Logacheva, A.I.; Logunov, A.V.; Razumovskij, I.M.

2004-01-01

Using X-ray diffraction and DS analyses the process of solid phase synthesis on cooperative comminution of components (Nb, Al, Cr) in a planetary ball mill is investigated. Powder nanocrystalline Nb 3 Al base alloys of various compositions with simultaneous introduction of chromium are synthesized. High power milling results in block size of ∼ 20 nm. It is shown that final chromium dissolution and partial decomposition of Nb(Al) supersaturated solid solutions proceed after heating up to 1100 deg C only. With the help of doping with niobium by the method of mechanical alloying, a two-phase alloy Nb 3 Al + Nb 2 Al having been produced by arc melting, is corrected by composition and transferred to the two-phase region of Nb 3 Al + Nb(Al). It is revealed that the process of niobium aluminide phase formation during mechanochemical synthesis and the process of mechanical activation of Nb-Al system intermetallics enriched with niobium always proceed through formation of supersaturated solid solutions. The mechanism of the process is probably associated with stacking faults formation due to deformation [ru

MICROSTRUCTURE AND TENSILE PROPERTIES OF Fe3Al-BASED ALLOYS WITH VC AND TiC ADDITIONS

Institute of Scientific and Technical Information of China (English)

W.L.Xu; Y.S.Sun; S.S.Ding

2001-01-01

Microstructure and tensile properties of Fe3Al-based alloys with additions of TiC andVC particles have been investigated.Results show that the formation of TiC particlesresults in the refinement of the macrostructure of as-cast ingots.Although the additionof VC particles does not cause significant change of the as-cast microstructure,themicrostructure of the alloy after hot-working and recrystallization has been found tobe refined.The formation of both VC and TiC particles results in the increase of yieldstrength,especially at high temperature of 600℃.

Computer aided cooling curve analysis for Al-5Si and Al-11Si alloys ...

African Journals Online (AJOL)

The effect of grain refiner, modifier, and combination of grain refiner cum modifier was studied on Al-5Si and Al-11Si alloys using computer aided cooling curve analysis. For combined grain refinement and modification effect, Al-Ti-B-Sr single master alloy was developed that acted as both grain refiner and modifier.

Separation of primary solid phases from Al-Si alloy melts

Directory of Open Access Journals (Sweden)

Ki Young Kim

2014-07-01

Full Text Available The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts. This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation, draining, filtration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C

Science.gov (United States)

Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon

2018-04-01

In this paper, the Al/Cr coating was fabricated on the surface of Ti2AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2AlNb alloy with prolonged air exposure at 900 °C. Al2O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2O3. Besides, Cr2O3 was produced under Al2O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2AlNb alloy increases oxidation resistance.

Processing and properties of Nb-Ti-based alloys

International Nuclear Information System (INIS)

Sikka, V.K.; Viswanathan, S.

1992-01-01

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep test at 650 C and 172 MPa was conducted on the base alloy which contained 40Nb-40Ti-10Al-10Cr. A second alloy was modified with 0.11 at. % carbon and 0.07 at. % yttrium. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1,100 C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400, 600, 700, 800, 900, and 1,000 C, and for the modified alloy at room temperature, 400, 600, 700, and 800 C. Oxidation tests on the base alloy and modified alloy, as measured by weight change, were carried out at 600, 700, 800, and 900 C. Both the base alloy and the modified alloy were extremely ductile and were cold rolled to the final sheet thickness of 0.8 mm without an intermediate anneal. The modified alloy exhibited some edge cracking during cold during cold rolling. Both alloys recrystallized at the end of a 0.5-h annealing treatment. The alloys exhibited moderate strength and oxidation resistance below 600 C, similar to the results of alloys reported in the literature

Electrodeposition of Al-Mn alloy on AZ31B magnesium alloy in molten salts

International Nuclear Information System (INIS)

Zhang Jifu; Yan Chuanwei; Wang Fuhui

2009-01-01

The Al-Mn alloy coatings were electrodeposited on AZ31B Mg alloy in AlCl 3 -NaCl-KCl-MnCl 2 molten salts at 170 deg. C aiming to improve the corrosion resistance. However, in order to prevent AZ31B Mg alloy from corrosion during electrodeposition in molten salts and to ensure excellent adhesion of coatings to the substrate, AZ31B Mg alloy should be pre-plated with a thin zinc layer as intermediate layer. Then the microstructure, composition and phase constituents of the coatings were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD). It was indicated that, by adjusting the MnCl 2 content in the molten salts from 0.5 wt% to 2 wt%, the Mn content in the alloy coating was increased and the phase constituents were changed from f.c.c Al-Mn solid solution to amorphous phase. The corrosion resistance of the coatings was evaluated by potentiodynamic polarization measurements in 3.5% NaCl solution. It was confirmed that the Al-Mn alloy coatings exhibited good corrosion resistance with a chear passive region and significantly reduced corrosion current density at anodic potentiodynamic polarization. The corrosion resistance of the alloy coatings was also related with the microstructure and Mn content of the coatings.

The Age-Precipitations Structure Of Al-Mg-Ge Alloy Aged At 473K

Directory of Open Access Journals (Sweden)

Kawai A.

2015-06-01

Full Text Available The Al-Mg-Ge alloy is one of the age-hardening aluminum alloy after solution heat treatment. It has been proposed that the age-precipitation behavior of Al-Mg-Ge alloy is different from that of Al-Mg-Si alloy according to our previous works about the microstructure on Al-Mg-Ge alloy over-aged at 523K. For example, The hardness of peak aged Al-1.0mass%Mg2Ge alloy is higher than that of Al-1.0mass%Mg2Si alloy. The precipitates in the over-aged samples have been classified as some metastable phases, such as the β’-phase and Type-A precipitates and equilibrium phase of β-Mg2Ge by TEM observation. There a few reports about microstructure on Al-Mg-Ge alloys observed by TEM for different aging times. The age-precipitations structure of Al-Mg-Ge alloy has not been became clear. In this work, TEM observation was investigated the microstructure on Al-1.0mass%Mg2Ge alloy for difference aging times aged at 473K.

High-temperature phase transformation in Cr added TiAl base alloy

Energy Technology Data Exchange (ETDEWEB)

Abe, E.; Niinobe, K.; Nobuki, M.; Nakamura, M.; Tsujimoto, T.

1999-07-01

The authors have investigated a microstructure evolution of a Ti-48Al-3.5Cr (in at.%) alloy at high-temperatures ({gt} 1,473K). In the alloy annealed at 1673K for 1.8ks, followed by air-cooling, a characteristic microstructure with a feathery fashion was uniformly formed. From a cooling-rate-controlling study, it was found that formation of the feathery structure is accomplished during continuous cooling from 1673K to 1573K, within the {alpha} + {gamma} two-phase region. Transmission electron microscopy revealed that the feathery structure is composed of lamellar colonies (5--10{micro}m) which are crystallographically tilted slightly (a few degree) with their neighbors. A surprising fact is that lamellae in each colony are mostly the {gamma} phase with few {alpha}{sub 2} phase less than 5% in volume. This suggests that the feathery structure is a metastable product and has not resulted from the {alpha} {r{underscore}arrow} {alpha} + {gamma} transformation above 1,573 K. Instead, the feathery structure formation should be attributed to the non-equilibrium {alpha} {r{underscore}arrow} {gamma} transformation which occurs at high-temperatures with a small degree of supercooling. The authors discuss this interesting phase transformation in terms of the {alpha} {r{underscore}arrow} {gamma} massive transformation, based on the continuous-cooling-transformation (CCT) diagram constructed for the present alloy.

Laser alloyed Al-Ni-Fe coatings

CSIR Research Space (South Africa)

Pityana, SL

2008-10-01

Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

Effect of Al alloying on the martensitic temperature in Ti-Ta shape memory alloys

Energy Technology Data Exchange (ETDEWEB)

Ferrari, Alberto; Rogal, Jutta; Drautz, Ralf [Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universitaet Bochum (Germany)

2017-07-01

Ti-Ta-based alloys are promising candidates as high temperature shape memory alloys (HTSMAs) for actuators and superelastic applications. The shape memory mechanism involves a martensitic transformation between the low-temperature α'' phase (orthorhombic) and the high-temperature β phase (body-centered cubic). In order to prevent the degradation of the shape memory effect, Ti-Ta needs to be alloyed with further elements. However, this often reduces the martensitic temperature M{sub s}, which is usually strongly composition dependent. The aim of this work is to analyze how the addition of a third element to Ti-Ta alloys affects M{sub s} by means of electronic structure calculations. In particular, it will be investigated how alloying Al to Ti-Ta alters the relative stability of the α'' and β phases. This understanding will help to identify new alloy compositions featuring both a stable shape memory effect and elevated transformation temperatures.

Solidified structure of Al-Pb-Cu alloys

International Nuclear Information System (INIS)

Ikeda, Tetsuyuki; Nishi, Seiki; Kumeuchi, Hiroyuki; Tatsuta, Yoshinori.

1986-01-01

Al-Pb-Cu alloys were cast into bars or plates in different two metal mold casting processes in order to suppress gravity segregation of Pb and to achieve homogeneous dispersion of Pb phase in the alloys. Solidified structures were analyzed by a video-pattern-analyzer. Plate castings 15 to 20 mm in thickness of Al-Pb-1 % Cu alloy containing Pb up to 5 % in which Pb phase particles up to 10 μm disperse are achieved through water cooled metal mold casting. The plates up to 5 mm in thickness containing Pb as much as 8 to 10 % cast in this process have dispersed Pb particles up to 5 μm in diameter in the surface layer. Al-8 % Pb-1 % Cu alloy bars 40 mm in diameter and 180 mm in height in which gravity segregation of Pb is prevented can be cast by movable and water sprayed metal mold casting at casting temperature 920 deg C and mold moving speed 1.0 mm/s. Pb phase particles 10 μm in mean size are dispersed in the bars. (author)

Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

Energy Technology Data Exchange (ETDEWEB)

Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

2016-12-15

The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

Structure and Mechanical Properties of Al-Cu-Fe-X Alloys with Excellent Thermal Stability

OpenAIRE

Školáková, Andrea; Novák, Pavel; Mejzlíková, Lucie; Průša, Filip; Salvetr, Pavel; Vojtěch, Dalibor

2017-01-01

In this work, the structure and mechanical properties of innovative Al-Cu-Fe based alloys were studied. We focused on preparation and characterization of rapidly solidified and hot extruded Al-Cu-Fe, Al-Cu-Fe-Ni and Al-Cu-Fe-Cr alloys. The content of transition metals affects mechanical properties and structure. For this reason, microstructure, phase composition, hardness and thermal stability have been investigated in this study. The results showed exceptional thermal stability of these allo...

Chemical and electrical characterisation of the segregation of Al from a CuAl alloy (90%:10% wt) with thermal anneal

Energy Technology Data Exchange (ETDEWEB)

Byrne, C., E-mail: conor.byrne2@mail.dcu.ie [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Brady, A.; Walsh, L.; McCoy, A.P.; Bogan, J. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); McGlynn, E. [School of Physical Sciences, National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland); Rajani, K.V. [School of Electronic Engineering, Dublin City University, Dublin 9 (Ireland); Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); School of Physical Sciences, National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)

2016-01-29

A copper–aluminium (CuAl) alloy (90%:10% wt) has been investigated in relation to segregation of the alloying element Al, from the alloy bulk during vacuum anneal treatments. X-ray photoelectron spectroscopy (XPS) measurements were used to track the surface enrichment of Al segregating from the alloy bulk during in situ ultra-high vacuum anneals. Secondary ion mass spectroscopy (SIMS) indicates a build-up of Al at the surface of the annealed alloy relative to the bulk composition. Metal oxide semiconductor (MOS) CuAl/SiO{sub 2}/Si structures show a shift in flatband voltage upon thermal anneal consistent with the segregation of the Al to the alloy/SiO{sub 2} interface. Electrical four point probe measurements indicate that the segregation of Al from the alloy bulk following thermal annealing results in a decrease in film resistivity. X-ray diffraction data shows evidence for significant changes in crystal structure upon annealing, providing further evidence for expulsion of Al from the alloy bulk. - Highlights: • CuAl alloy (90%:Al 10% wt) deposited and vacuum annealed • XPS and SIMS data show segregation of Al from the alloy bulk. • Chemical changes seen indicate the reduction of Cu oxide and growth of Al Oxide. • Electrical measurements indicate a chemical change at the metal/SiO{sub 2} interface. • All data consistent with Cu diffusion barrier layer formed.

Application of computational thermodynamics to the determination of thermophysical properties as a function of temperature for multicomponent Al-based alloys

International Nuclear Information System (INIS)

Nascimento, Fabiana C.; Paresque, Mara C.C.; Castro, José A. de; Jácome, Paulo A.D.; Garcia, Amauri; Ferreira, Ivaldo L.

2015-01-01

Highlights: • A model coupled to a computational thermodynamics software is proposed to compute thermophysical properties. • The model applies to multicomponent alloys and has been validated against experimental results. • Density and specific heat as a function of temperature are computed for Al–Si–Cu alloys. - Abstract: Despite the technological importance of Al–Si–Cu alloys in manufacturing processes involving heat transfer, such as welding, casting and heat treatment, thermophysical properties of this system of alloys are very scarce in the literature. In this paper, a model connected to a computational thermodynamics software is proposed permitting density and specific heats as a function of temperature and enthalpy of transformations to be numerically determined. The model is pre-validated against experimental density as a function of temperature for liquid and solid phases of A319 and 7075 alloys found in the literature and validated against experimental density values for the solid phase of an Al-6 wt%Cu-1 wt%Si alloy determined in the present study. In both cases the numerical predictions are in good agreement with the experimental results. Specific heat and temperatures and heats of transformation are also numerically determined for this ternary Al-based alloy.

Application of computational thermodynamics to the determination of thermophysical properties as a function of temperature for multicomponent Al-based alloys

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Fabiana C. [Fluminense Federal University, Graduate Program in Metallurgical Engineering, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil); Paresque, Mara C.C. [Fluminense Federal University, Graduate Program in Mechanical Engineering, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil); Castro, José A. de [Fluminense Federal University, Graduate Program in Metallurgical Engineering, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil); Jácome, Paulo A.D. [Fluminense Federal University, Graduate Program in Mechanical Engineering, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil); Garcia, Amauri, E-mail: amaurig@fem.unicamp.br [University of Campinas – UNICAMP, Department of Manufacturing and Materials Engineering, 13083-860 Campinas, SP (Brazil); Ferreira, Ivaldo L. [Fluminense Federal University, Graduate Program in Mechanical Engineering, Av. dos Trabalhadores, 420-27255-125 Volta Redonda, RJ (Brazil)

2015-11-10

Highlights: • A model coupled to a computational thermodynamics software is proposed to compute thermophysical properties. • The model applies to multicomponent alloys and has been validated against experimental results. • Density and specific heat as a function of temperature are computed for Al–Si–Cu alloys. - Abstract: Despite the technological importance of Al–Si–Cu alloys in manufacturing processes involving heat transfer, such as welding, casting and heat treatment, thermophysical properties of this system of alloys are very scarce in the literature. In this paper, a model connected to a computational thermodynamics software is proposed permitting density and specific heats as a function of temperature and enthalpy of transformations to be numerically determined. The model is pre-validated against experimental density as a function of temperature for liquid and solid phases of A319 and 7075 alloys found in the literature and validated against experimental density values for the solid phase of an Al-6 wt%Cu-1 wt%Si alloy determined in the present study. In both cases the numerical predictions are in good agreement with the experimental results. Specific heat and temperatures and heats of transformation are also numerically determined for this ternary Al-based alloy.

Effects of samarium (Sm) additions on the microstructure and mechanical properties of as-cast and hot-extruded Mg-5 wt%Al-3 wt%Ca-based alloys

International Nuclear Information System (INIS)

Son, Hyeon-Taek; Lee, Jae-Seol; Kim, Dae-Guen; Yoshimi, Kyosuke; Maruyama, Kouichi

2009-01-01

Samarium (Sm) additions to as-cast Mg-5Al-3Ca-based alloys result in changes, such as equiaxed grains and a refined grain size. The microstructure of as-cast Mg-5Al-3Ca-xSm alloys consists of an α-Mg matrix, a (Mg, Al) 2 Ca eutectic phase, and an Al 2 Sm intermetallic compound. In as-cast alloys, the (Mg, Al) 2 Ca eutectic phase was located at grain boundaries with a chain structure, and the Al 2 Sm intermetallic compounds were homogeneously distributed at the α-Mg matrix and grain boundaries. The eutectic phase of the extruded alloys was elongated in the extrusion direction and crushed into fine particles because of severe deformation during hot extrusion, and the grain size was refined with an increased amount of Sm addition. The maximum values of the yield strength and tensile strength were 313 MPa and 330 MPa at 2 wt%Sm alloy content, respectively

Vacuum brazing of electroless Ni-P alloy-coated SiCp/Al composites using aluminum-based filler metal foil

Science.gov (United States)

Wang, Peng; Xu, Dongxia; Niu, Jitai

2016-12-01

Using rapidly cooled (Al-10Si-20Cu-0.05Ce)-1Ti (wt%) foil as filler metal, the research obtained high-performance joints of electroless Ni-P alloy-coated aluminum matrix composites with high SiC particle content (60 vol%, SiCp/Al-MMCs). The effect of brazing process on joint properties and the formation of Al-Ni and Al-Cu-Ni intermetallic compounds were investigated, respectively. Due to the presence of Ni-P alloy coating, the wettability of liquid filler metal on the composites was improved obviously and its contact angle was only 21°. The formation of Al3Ni2 and Al3(CuNi)2 intermetallic compounds indicated that well metallurgical bonding occurred along the 6063Al matrix alloy/Ni-P alloy layer/filler metal foil interfaces by mutual diffusion and dissolution. And the joint shear strength increased with increasing the brazing temperature from 838 to 843 K or prolonging the soaking time from 15 to 35 min, while it decreased a lot because of corrosion occurring in the 6063Al matrix at high brazing temperature of 848 K. Sound joints with maximum shear strength of 112.5 MPa were obtained at 843 K for soaking time of 35 min. In this research, the beneficial effect of surface metallization by Ni-P alloy deposits on improving wettability on SiCp/Al-MMCs was demonstrated, and capable welding parameters were broadened as well.

Microstructure evolution of 7050 Al alloy during age-forming

International Nuclear Information System (INIS)

Chen, Junfeng; Zou, Linchi; Li, Qiang; Chen, Yulong

2015-01-01

The microstructure evolution of the 7050 Al alloy treated by age-forming was studied using a designed device which can simulate the age-forming process. The grain shape, grain boundary misorientation and grain orientation evolution of 7050 Al alloy during age-forming have been quantitatively characterized by electron backscattering diffraction technique. The results show that age-forming produced abundant low-angle boundaries and elongated grains, which attributed to stress induced dislocation movement and grain boundary migration during the age-forming process. On the other side, the stress along rolling direction caused some unstable orientation grains to rotate towards the Brass and S orientations during the age-forming process. Hence, the intensity of the rolling texture orientation in age-formed samples is enhanced. But this effect decays gradually with increasing aging time, since stress decreases and precipitation hardening occurs during the age-forming process. - Highlights: • Quantitative analysis of grain evolution of 7050 Al alloys during age-forming • Stress induces some grain rotation of 7050 Al alloys during age-forming. • Creep leads to elongate grain of 7050 Al alloys during age-forming. • Obtains a trend on texture evolution during age-forming applied stress

Neural network potential for Al-Mg-Si alloys

Science.gov (United States)

Kobayashi, Ryo; Giofré, Daniele; Junge, Till; Ceriotti, Michele; Curtin, William A.

2017-10-01

The 6000 series Al alloys, which include a few percent of Mg and Si, are important in automotive and aviation industries because of their low weight, as compared to steels, and the fact their strength can be greatly improved through engineered precipitation. To enable atomistic-level simulations of both the processing and performance of this important alloy system, a neural network (NN) potential for the ternary Al-Mg-Si has been created. Training of the NN uses an extensive database of properties computed using first-principles density functional theory, including complex precipitate phases in this alloy. The NN potential accurately reproduces most of the pure Al properties relevant to the mechanical behavior as well as heat of solution, solute-solute, and solute-vacancy interaction energies, and formation energies of small solute clusters and precipitates that are required for modeling the early stage of precipitation and mechanical strengthening. This success not only enables future detailed studies of Al-Mg-Si but also highlights the ability of NN methods to generate useful potentials in complex alloy systems.

Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

Science.gov (United States)

Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

2005-05-01

It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. (c) 2005 Wiley Periodicals, Inc.

Influence of Iron in AlSi10MgMn Alloy

Directory of Open Access Journals (Sweden)

Žihalová M.

2014-12-01

Full Text Available Presence of iron in Al-Si cast alloys is common problem mainly in secondary (recycled aluminium alloys. Better understanding of iron influence in this kind of alloys can lead to reduction of final castings cost. Presented article deals with examination of detrimental iron effect in AlSi10MgMn cast alloy. Microstructural analysis and ultimate tensile strength testing were used to consider influence of iron to microstructure and mechanical properties of selected alloy.

Database on Performance of Neutron Irradiated FeCrAl Alloys

Energy Technology Data Exchange (ETDEWEB)

Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Univ. of Wisconsin, Madison, WI (United States); Littrell, Ken [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parish, Chad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-08-01

The present report summarizes and discusses the database on radiation tolerance for Generation I, Generation II, and commercial FeCrAl alloys. This database has been built upon mechanical testing and microstructural characterization on selected alloys irradiated within the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) up to doses of 13.8 dpa at temperatures ranging from 200°C to 550°C. The structure and performance of these irradiated alloys were characterized using advanced microstructural characterization techniques and mechanical testing. The primary objective of developing this database is to enhance the rapid development of a mechanistic understanding on the radiation tolerance of FeCrAl alloys, thereby enabling informed decisions on the optimization of composition and microstructure of FeCrAl alloys for application as an accident tolerant fuel (ATF) cladding. This report is structured to provide a brief summary of critical results related to the database on radiation tolerance of FeCrAl alloys.

Study of Bending Fatigue Properties of Al-Si Cast Alloy

Directory of Open Access Journals (Sweden)

Tillová E.

2017-09-01

Full Text Available Fatigue properties of casting Al-alloys are very sensitive to the microstructural features of the alloy (e.g. size and morphology of the eutectic Si, secondary dendrite arm spacing - SDAS, intermetallics, grain size and casting defects (porosity and oxides. Experimental study of bending fatigue properties of secondary cast alloys have shown that: fatigue tests up to 106-107cycles show mean fatigue limits of approx. 30-49 MPa (AlSi9Cu3 alloy - as cast state, approx. 65-76 MPa (AlSi9Cu3 alloy after solution treatment and 60-70 MPa (self-hardened AlZn10Si8Mg alloy in the tested casting condition; whenever large pore is present at or near the specimen’s surface, it will be the dominant cause of fatigue crack initiation; in the absence of large casting defects, the influence of microstructural features (Si morphology; Fe-rich phases on the fatigue performance becomes more pronounced.

Development of weldable, corrosion-resistant iron-aluminide (FeAl) alloys

Energy Technology Data Exchange (ETDEWEB)

Maziasz, P.J.; Goodwin, G.M.; Wang, X.L.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

1997-04-01

A boron-microalloyed FeAl alloy (Fe-36Al-0.2Mo-0.05Zr-0.13C, at.%, with 100-400 appm B) with improved weldability and mechanical properties was developed in FY 1994. A new scale-up and industry technology development phase for this work began in FY 1995, pursuing two parallel paths. One path was developing monolithic FeAl component and application technology, and the other was developing coating/cladding technology for alloy steels, stainless steels and other Fe-Cr-Ni alloys. In FY 1995, it was found that cast FeAl alloys had good strength at 700-750{degrees}C, and some (2.5%) ductility in air at room-temperature. Hot-extruded FeAl with refined grain size was found to have ductility and to also have good impact-toughness at room-temperature. Further, it was discovered that powder-metallurgy (P/M) FeAl, consolidated by direct hot-extrusion at 950-1000{degrees}C to have an ultra fine-grained microstructure, had the highest ductility, strength and impact-toughness ever seen in such intermetallic alloys.

Ab initio study on the thermal properties of the fcc Al3Mg and Al3Sc alloys

International Nuclear Information System (INIS)

Li Donglin; Chen Ping; Yi Jianxiong; Tang Biyu; Peng Liming; Ding Wenjiang

2009-01-01

Ab initio density functional theory (DFT) and density function perturbation theory (DFPT) have been used to investigate the thermal properties of the fcc Al 3 Mg and Al 3 Sc alloys over a wide range of pressure and temperature, in comparison with fcc Al. Phonon dispersions were obtained at equilibrium and strained configurations by density functional perturbation theory. Using the quasiharmonic approximation for the free energy, several thermal quantities of interest, such as the thermal Grueneisen parameter, heat capacity, thermal expansion coefficient and entropy, were calculated as a function of temperature and pressure, and the variation features of these quantities were discussed in detail. This investigation provides useful information for design and applications of technologically relevant Al-based alloys.

Discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys as anodes for Mg-air battery

International Nuclear Information System (INIS)

Wang, Naiguang; Wang, Richu; Peng, Chaoqun; Peng, Bing; Feng, Yan; Hu, Chengwang

2014-01-01

Highlights: • We investigate the effect of indium on the discharge behaviour of Mg-Al-Pb alloy. • We evaluate the performance of Mg-air batteries with Mg-Al-Pb and Mg-Al-Pb-In anodes. • We analyze the activation mechanism of Mg-Al-Pb-In alloy in the discharge process. - Abstract: The discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys in 3.5 wt.% NaCl solution is investigated by electrochemical techniques, and compared with that of pure magnesium. The results show that Mg-Al-Pb-In alloy provides a more negative potential and exhibits a higher utilization efficiency in contrast with Mg-Al-Pb alloy and pure magnesium during the half-cell test at a large current density, and gives desirable discharge performance when used as anode for Mg- air battery. The peak power density of the Mg-air battery with Mg-Al-Pb-In anode is 94.5 mW cm −2 , which is comparable with those of Mg-H 2 O 2 semi-fuel batteries. Moreover, the activation mechanism of Mg-Al-Pb-In alloy during the discharge process is also analyzed

Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

Science.gov (United States)

2013-02-01

concerns. These braze alloys use a high Si content to produce a low melting Al-Si near eutectic alloy. The recommended 11 brazing temperature for A A...each successive dip enhancing the 21 high temperature Si enrichment outside of the braze gap and decreasing the Si content within the braze gap.6...Nevertheless equilibrium phases should be considered as a reference point for grain boundaries after high temperature brazing . Recent literature [22

Laser Cladding of γ-TiAl Intermetallic Alloy on Titanium Alloy Substrates

Science.gov (United States)

Maliutina, Iuliia Nikolaevna; Si-Mohand, Hocine; Piolet, Romain; Missemer, Florent; Popelyukh, Albert Igorevich; Belousova, Natalya Sergeevna; Bertrand, Philippe

2016-01-01

The enhancement of titanium and titanium alloy's tribological properties is of major interest in many applications such as the aerospace and automotive industry. Therefore, the current research paper investigates the laser cladding of Ti48Al2Cr2Nb powder onto Ti6242 titanium alloy substrates. The work was carried out in two steps. First, the optimal deposition parameters were defined using the so-called "combined parameters," i.e., the specific energy E specific and powder density G. Thus, the results show that those combined parameters have a significant influence on the geometry, microstructure, and microhardness of titanium aluminide-formed tracks. Then, the formation of dense, homogeneous, and defect-free coatings based on optimal parameters has been investigated. Optical and scanning electron microscopy techniques as well as energy-dispersive spectroscopy and X-ray diffraction analyses have shown that a duplex structure consisting of γ-TiAl and α 2-Ti3Al phases was obtained in the coatings during laser cladding. Moreover, it was shown that produced coatings exhibit higher values of microhardness (477 ± 9 Hv0.3) and wear resistance (average friction coefficient is 0.31 and volume of worn material is 5 mm3 after 400 m) compared to those obtained with bare titanium alloy substrates (353 Hv0.3, average friction coefficient is 0.57 and a volume of worn material after 400 m is 35 mm3).

Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

International Nuclear Information System (INIS)

Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

2008-01-01

The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

The mechanical properties of magnesium matrix composites reinforced with 10 wt.% W14Al86 alloy particles

International Nuclear Information System (INIS)

Tang, H.G.; Ma, X.F.; Zhao, W.; Cai, S.G.; Zhao, B.; Qiao, Z.H.

2007-01-01

The Mg-based metal matrix composite reinforced by 10 wt.% W 14 Al 86 alloy particles has been prepared by mechanical alloying and press-forming process. X-ray diffraction studies confirm the formation of the composite. Microstructure characterization of the samples reveals the uniform distribution of fine W 14 Al 86 alloy. Mechanical properties characterization revealed that the reinforcement of W 14 Al 86 alloy lead to a significant increase in hardness and tensile strength of Mg and AZ91

Enhanced Piezoelectric Response of AlN via CrN Alloying

Energy Technology Data Exchange (ETDEWEB)

Manna, Sukriti; Talley, Kevin R.; Gorai, Prashun; Mangum, John; Zakutayev, Andriy; Brennecka, Geoff L.; Stevanović, Vladan; Ciobanu, Cristian V.

2018-03-01

Since AlN has emerged as an important piezoelectric material for a wide variety of applications, efforts have been made to increase its piezoelectric response via alloying with transition metals that can substitute for Al in the wurtzite lattice. We report on density functional theory calculations of structure and properties of the CrxAl1-xN system for Cr concentrations ranging from zero to beyond the wurtzite-rocksalt transition point. By studying the different contributions to the longitudinal piezoelectric coefficient, we propose that the physical origin of the enhanced piezoelectricity in CrxAl1-xN alloys is the increase of the internal parameter u of the wurtzite structure upon substitution of Al with the larger Cr ions. Among a set of wurtzite-structured materials, we find that CrxAl1-xN has the most sensitive piezoelectric coefficient with respect to alloying concentration. Based on these results, we propose that CrxAl1-xN is a viable piezoelectric material whose properties can be tuned via Cr composition. We support this proposal by combinatorial synthesis experiments, which show that Cr can be incorporated in the AlN lattice up to 30% before a detectable transition to rocksalt occurs. At this Cr content, the piezoelectric modulus d33 is approximately 4 times larger than that of pure AlN. This finding, combined with the relative ease of synthesis under nonequilibrium conditions, may position CrxAl1-xN as a prime piezoelectric material for applications such as resonators and acoustic wave generators.

Enhanced Piezoelectric Response of AlN via CrN Alloying

Science.gov (United States)

Manna, Sukriti; Talley, Kevin R.; Gorai, Prashun; Mangum, John; Zakutayev, Andriy; Brennecka, Geoff L.; Stevanović, Vladan; Ciobanu, Cristian V.

2018-03-01

Since AlN has emerged as an important piezoelectric material for a wide variety of applications, efforts have been made to increase its piezoelectric response via alloying with transition metals that can substitute for Al in the wurtzite lattice. We report on density functional theory calculations of structure and properties of the Crx Al1 -x N system for Cr concentrations ranging from zero to beyond the wurtzite-rocksalt transition point. By studying the different contributions to the longitudinal piezoelectric coefficient, we propose that the physical origin of the enhanced piezoelectricity in Crx Al1 -x N alloys is the increase of the internal parameter u of the wurtzite structure upon substitution of Al with the larger Cr ions. Among a set of wurtzite-structured materials, we find that Crx Al1 -x N has the most sensitive piezoelectric coefficient with respect to alloying concentration. Based on these results, we propose that Crx Al1 -x N is a viable piezoelectric material whose properties can be tuned via Cr composition. We support this proposal by combinatorial synthesis experiments, which show that Cr can be incorporated in the AlN lattice up to 30% before a detectable transition to rocksalt occurs. At this Cr content, the piezoelectric modulus d33 is approximately 4 times larger than that of pure AlN. This finding, combined with the relative ease of synthesis under nonequilibrium conditions, may position Crx Al1 -x N as a prime piezoelectric material for applications such as resonators and acoustic wave generators.

Formation of coarse Al13Fe4 particles and their effects in an RS/PM Al-Fe-V-Si alloy

International Nuclear Information System (INIS)

Lee, Sunghak; Lee, D.Y.; Ahn, Sangho.

1991-01-01

The present paper analyzed the fracture behavior of an RS/PM Al-Fe-V-Si alloy after high temperature exposure, in particular the effects of coarse Al13Fe4 particles formed during the exposure at 480 C. In situ SEM observations of crack opening processes found that brittle cleavage fracture occurred at these coarse Al13Fe4 particles, leading to the reduction in strength, fracture toughness, and ductility of the Al-Fe-V-Si alloy exposed to high temperatures. The results of fracture toughness were also interpreted using a simplified ductile fracture initiation model based on a basic assumption that crack extension starts to occur at a certain critical strain over a microstructurally significant critical distance. This model correlates microstructure to fracture toughness, confirming that the presence of coarse Al13Fe4 particles is the main metallurgical factor for the embrittlement phenomenon in the Al-Fe-V-Si alloy after high temperature exposure. 12 refs

Microstructure and wear behaviour of FeAl-based composites ...

Indian Academy of Sciences (India)

FeAl-based composites; precipitation; mechanical properties; wear. 1. Introduction. Fe–Al alloys ... ground to 1500 grit and polished with alumina powder. (0.5 μm). ... Alloy-2 (figure 2) consists of cuboid-shaped ZrC (region C), an FeAl matrix ...

L2₁ and XA Ordering Competition in Hafnium-Based Full-Heusler Alloys Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb).

Science.gov (United States)

Wang, Xiaotian; Cheng, Zhenxiang; Wang, Wenhong

2017-10-20

For theoretical designing of full-Heusler based spintroinc materials, people have long believed in the so-called Site Preference Rule (SPR). Very recently, according to the SPR, there are several studies on XA-type Hafnium-based Heusler alloys X₂YZ, i.e., Hf₂VAl, Hf₂CoZ (Z = Ga, In) and Hf₂CrZ (Z = Al, Ga, In). In this work, a series of Hf₂-based Heusler alloys, Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb), were selected as targets to study the site preferences of their atoms by first-principle calculations. It has been found that all of them are likely to exhibit the L2₁-type structure instead of the XA one. Furthermore, we reveal that the high values of spin-polarization of XA-type Hf₂VZ (Z = Al, Ga, In, Tl, Si, Ge, Sn, Pb) alloys have dropped dramatically when they form the L2₁-type structure. Also, we prove that the electronic, magnetic, and physics nature of these alloys are quite different, depending on the L2₁-type or XA-type structures.

Fabrication and mechanical properties of quasicrystal-reinforced Al-Mn-Mm alloys

International Nuclear Information System (INIS)

Jun, Joong-Hwan; Kim, Jeong-Min; Kim, Ki-Tae; Jung, Woon-Jae

2007-01-01

Microstructures and room temperature mechanical properties of quasicrystal-reinforced Al 94-x Mn 6 Mm x (Mm: misch metal, x = 0-6 at.%) alloys have been studied systematically. Cylindrical rod samples with 3 mm in diameter were synthesized by injection-casting into a Cu mould and analyzed by means of X-ray diffractometry, differential scanning calorimetry, optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectrometry. Mechanical properties of the cylindrical rods were measured at room temperature by compression tests. The Al 94 Mn 6 alloy contains hexagonal-shape particles and long needle-shape Al 6 Mn precipitates surrounded by α-Al matrix. An addition of Mm into the Al 94 Mn 6 alloy generates icosahedral quasicrystalline phase (IQC) with an extinction of hexagonal and Al 6 Mn phases, and the fraction of IQC increases continuously with an increase in Mm content. Compressive yield strength (σ cys ) and ultimate compressive strength (σ ucs ) of the Al-Mn-Mm alloys are improved with Mm content up to 4%, whereas elongation is steeply deteriorated by the Mm addition. The Al 90 Mn 6 Mm 4 alloy exhibits the highest 570 and 783 MPa of σ cys and σ ucs , respectively, both of which are comparable to those of Al 90 Mn 6 Ce 4 alloy

Optimization of the boron content in FeAl (40 at. % Al) alloys

International Nuclear Information System (INIS)

Webb, G.; Juliet, P.; Lefort, A.

1993-01-01

FeAl intermetallic alloys are of interest for several high temperature applications due to excellent oxidation resistance, low density, and relatively low cost. Attempts to further increase the ductility of iron-rich FeAl have met with, at best, marginal success. Of the ductilization techniques employed, B doping appears to be a promising method for obtaining enhanced ductility and high strength in iron rich FeAl. Boron additions enhance the ductility of these alloys by increasing the grain boundary cohesive strength which reduces the tendency for intergranular fracture. The goal of the present work was to determine the optimum B concentration for increasing ambient temperature ductility. To accomplish this, a series of three iron rich FeAl alloys of similar Fe stoichiometries were doped with different levels of B (0,12, and 80 wppm). Secondary ion mass spectrometry (SIMS) was conducted on these alloys for evaluation of the B partitioning after consolidation by extrusion. Ambient temperature tensile testing and SEM fractography were then used to evaluate the effect of such additions on ambient temperature ductility in air. The results of these experiments indicate that optimum ductility is obtained from a homogeneous distribution of boron in which boride precipitation is limited

Molar Volume Analysis of Molten Ni-Al-Co Alloy by Measuring the Density

Institute of Scientific and Technical Information of China (English)

XIAO Feng; FANG Liang; FU Yuechao; YANG Lingchuan

2004-01-01

The density of molten Ni-Al-Co alloys was measured in the temperature range of 1714～1873K using a modified pycnometric method, and the molar volume of molten alloys was analyzed. The density of molten Ni-Al-Co alloys was found to decrease with increasing temperature and Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys increases with increasing Co concentration in alloys. The molar volume of molten Ni-Al-Co alloys shows a negative deviation from the linear molar volume.

Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

OpenAIRE

Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E.; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

2016-01-01

This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s−1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hystere...

Phase diagrams of aluminium alloys of Al-Cu-Mg, Al-Mg-Si-Cu, and Al-Mg-Li system

International Nuclear Information System (INIS)

Ber, L.B.; Kaputkin, E.Ya.

2001-01-01

Isothermal diagrams of phase transformations (DPT) and temperature-time charts (TTC) of variation of electric conductivity and of mechanical features at tension were plotted following thermal treatment according to the pattern of direct hardening and ageing and according to the pattern of normal aging for D16 commercial alloy, Al-Cu-Mg model alloy of the same system, AD37 commercial alloys of Al-Mg-Si-Cu and 1424 one of Al-Li-Mg system. Phase transformations were studied by means of fluorescence electron microscopy, micro-X-ray spectral analysis, X-ray phase analysis of single crystals and polycrystals and differential scanning calorimetry. For every alloy comparison of TTC and DPT enables to clarity the mechanism of phase composition effect on features and to optimize conditions of hardening cooling and ageing [ru

High strength nanostructured Al-based alloys through optimized processing of rapidly quenched amorphous precursors.

Science.gov (United States)

Kim, Song-Yi; Lee, Gwang-Yeob; Park, Gyu-Hyeon; Kim, Hyeon-Ah; Lee, A-Young; Scudino, Sergio; Prashanth, Konda Gokuldoss; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

2018-01-18

We report the methods increasing both strength and ductility of aluminum alloys transformed from amorphous precursor. The mechanical properties of bulk samples produced by spark-plasma sintering (SPS) of amorphous Al-Ni-Co-Dy powders at temperatures above 673 K are significantly enhanced by in-situ crystallization of nano-scale intermetallic compounds during the SPS process. The spark plasma sintered Al 84 Ni 7 Co 3 Dy 6 bulk specimens exhibit 1433 MPa compressive yield strength and 1773 MPa maximum strength together with 5.6% plastic strain, respectively. The addition of Dy enhances the thermal stability of primary fcc Al in the amorphous Al-TM -RE alloy. The precipitation of intermetallic phases by crystallization of the remaining amorphous matrix plays important role to restrict the growth of the fcc Al phase and contributes to the improvement of the mechanical properties. Such fully crystalline nano- or ultrafine-scale Al-Ni-Co-Dy systems are considered promising for industrial application because their superior mechanical properties in terms of a combination of very high room temperature strength combined with good ductility.

Influence of Microstructure on Corrosion Property of Mg-Al-Zn Alloy

International Nuclear Information System (INIS)

Lee, Jeong Ja; Na, Seung Chan; Yang, Won Seong; Hwang, WoonSuk; Jang, Si Sung; Yoo, Hwang Ryong

2006-01-01

Influence of microstructure on the corrosion property of Mg-Al-Zn Alloy was investigated using potentiodynamic polarization experiments, galvanic coupling experiments, and scanning electron microscopy in sodium chloride solutions. Pitting was the mot common form of attack in chloride solution, and filiform corrosion was also occurred in AZ91D-T4 alloy. On the contrary, filiform attack in the bulk matrix was predominant corrosion form in AZ91D-T6 alloy, and the number and size of pit were decreased than those of AZ91D-T4 alloy. Galvanic coupling effect between Mg 17 Al 12 and matrix was existed, but the propagation of galvanic corrosion was localized only near the Mg 17 Al 12 phase in AZ91D-6T alloy. The corrosion resistance of Mg-Al matrix increased with decreasing Al content in the matrix. And, it could be regarded that Al content in the matrix is decreased by precipitation of Mg 17 Al 12 curing the aging treatment and it decreases the anodic reaction rate of the matrix and galvanic effect in AZ91D-T6 alloy. It could be considered that the composition and macrostructure of surface protective layer would be varied by precipitation of Mg 17 Al 12 and subsequent decreasing of Al content in the matrix. And it would contribute the corrosion resistance of AZ91D-T6 aging alloy

Structure of as cast L12 compounds in Al3Zr-base alloys containing Cu and Mn

International Nuclear Information System (INIS)

Virk, I.S.; Varin, R.A.

1991-01-01

It was first shown that the low symmetry, tetragonal DO 23 crystal structure of Al 3 Zr intermetallic can be changed to the related cubic L1 2 crystal structure by alloying with Ni (Al 5 NiZr 2 ) and Cu(Al 5 CuZr 2 ). It has been reported that previous work has successfully modified Al 3 Zr with Fe, Cu, Cr and Ni obtaining nearly single phase materials with L1 2 structure. However, they only studied the microstructure and mechanical properties of Fe - modified intermetallic (Al-6at% Fe-25at% Zr). The purpose of the paper is to describe and interpret experimental observations on the microstructure of Al 5 CuZr 2 and Al 66 Mn 9 Zr 25 (at.%) modifications of base Al 3 Zr intermetallic. The one modified with Mn has not been reported in literature although its Al 3 Ti - base counterpart has recently been successfully produced (3, 4)

Formation of AlFeSi phase in AlSi12 alloy with Ce addition

Directory of Open Access Journals (Sweden)

S. Kores

2012-04-01

Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

Mechanical property, biocorrosion and in vitro biocompatibility evaluations of Mg-Li-(Al)-(RE) alloys for future cardiovascular stent application.

Science.gov (United States)

Zhou, W R; Zheng, Y F; Leeflang, M A; Zhou, J

2013-11-01

Mg-Li-based alloys were investigated for future cardiovascular stent application as they possess excellent ductility. However, Mg-Li binary alloys exhibited reduced mechanical strengths due to the presence of lithium. To improve the mechanical strengths of Mg-Li binary alloys, aluminum and rare earth (RE) elements were added to form Mg-Li-Al ternary and Mg-Li-Al-RE quarternary alloys. In the present study, six Mg-Li-(Al)-(RE) alloys were fabricated. Their microstructures, mechanical properties and biocorrosion behavior were evaluated by using optical microscopy, X-ray diffraction, scanning electronic microscopy, tensile tests, immersion tests and electrochemical measurements. Microstructure characterization indicated that grain sizes were moderately refined by the addition of rare earth elements. Tensile testing showed that enhanced mechanical strengths were obtained, while electrochemical and immersion tests showed reduced corrosion resistance caused by intermetallic compounds distributed throughout the magnesium matrix in the rare-earth-containing Mg-Li alloys. Cytotoxicity assays, hemolysis tests as well as platelet adhesion tests were performed to evaluate in vitro biocompatibilities of the Mg-Li-based alloys. The results of cytotoxicity assays clearly showed that the Mg-3.5Li-2Al-2RE, Mg-3.5Li-4Al-2RE and Mg-8.5Li-2Al-2RE alloys suppressed vascular smooth muscle cell proliferation after 5day incubation, while the Mg-3.5Li, Mg-8.5Li and Mg-8.5Li-1Al alloys were proven to be tolerated. In the case of human umbilical vein endothelial cells, the Mg-Li-based alloys showed no significantly reduced cell viabilities except for the Mg-8.5Li-2Al-2RE alloy, with no obvious differences in cell viability between different culture periods. With the exception of Mg-8.5Li-2Al-2RE, all of the other Mg-Li-(Al)-(RE) alloys exhibited acceptable hemolysis ratios, and no sign of thrombogenicity was found. These in vitro experimental results indicate the potential of Mg-Li-(Al

The development of platinum-based alloys and their thermodynamic database

OpenAIRE

Cornish L.A.; Hohls J.; Hill P.J.; Prins S.; Süss R.; Compton D.N.

2002-01-01

A series of quaternary platinum-based alloys have been demonstrated to exhibit the same two-phase structure as Ni-based superalloys and showed good mechanical properties. The properties of ternary alloys were a good indication that the quaternary alloys, with their better microstructure, will be even better. The quaternary alloy composition has been optimised at Pt84:Al11:Ru2:Cr3 for the best microstructure and hardness. Work has begun on establishing a thermodynamic database for Pt-Al-Ru-Cr ...

Differential Scanning Calorimetry and Thermodynamic Predictions—A Comparative Study of Al-Zn-Mg-Cu Alloys

Directory of Open Access Journals (Sweden)

Gernot K.-H. Kolb

2016-08-01

Full Text Available Al-Zn-Mg-Cu alloys are widely used in aircraft applications because of their superior mechanical properties and strength/weight ratios. Commercial Al-Zn-Mg-Cu alloys have been intensively studied over the last few decades. However, well-considered thermodynamic calculations, via the CALPHAD approach, on a variation of alloying elements can guide the fine-tuning of known alloy systems and the development of optimized heat treatments. In this study, a comparison was made of the solidus temperatures of different Al-Zn-Mg-Cu alloys determined from thermodynamic predictions and differential scanning calorimetry (DSC measurements. A variation of the main alloying elements Zn, Mg, and Cu generated 38 experimentally produced alloys. An experimental determination of the solidus temperature via DSC was carried out according to a user-defined method, because the broad melting interval present in Al-Zn-Mg-Cu alloys does not allow the use of the classical onset method for pure substances. The software algorithms implemented in FactSage®, Pandat™, and MatCalc with corresponding commercially available databases were deployed for thermodynamic predictions. Based on these investigations, the predictive power of the commercially available CALPHAD databases and software packages was critically reviewed.

Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

International Nuclear Information System (INIS)

Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

2005-01-01

In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

Electrical resistivity of Al-Cu liquid binary alloy

Science.gov (United States)

Thakor, P. P.; Patel, J. J.; Sonvane, Y. A.; Jani, A. R.

2013-06-01

Present paper deals with the electrical resistivity (ρ) of liquid Al-Cu binary alloy. To describe electron-ion interaction we have used our parameter free model potential along with Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. To see the influence of exchange and correlation effect, Hartree, Taylor and Sarkar et al local field correlation functions are used. From present results, it is seen that good agreements between present results and experimental data have been achieved. Lastly we conclude that our model potential successfully produces the data of electrical resistivity (ρ) of liquid Al-Cu binary alloy.

Effect of Sn addition on the microstructure and deformation behavior of Mg-3Al alloy

International Nuclear Information System (INIS)

Suh, Byeong-Chan; Kim, Jae H.; Bae, Jun Ho; Hwang, Ji Hyun; Shim, Myeong-Shik; Kim, Nack J.

2017-01-01

Mg alloys generally suffer from their poor formability at low temperatures due to their strong basal texture and a lack of adequate deformation systems. In the present study, a small amount of Sn was added instead of Zn to Mg-3Al alloy to modify its deformation behavior and improve the stretch formability. Microstructural examinations of the deformed Mg-3Al-1Sn (AT31) alloy by electron backscatter diffraction and transmission electron microscopy show that prismatic slip is quite active during deformation, resulting in much lower r-values and planar anisotropy than the counterpart Mg-3Al-1Zn (AZ31) alloy. Polycrystal plasticity simulation based on visco-plasticity self-consistent (VPSC) model also shows that prismatic slip is the dominant deformation mode in AT31 alloy besides basal slip. As a consequence, AT31 alloy shows a much higher stretch formability than AZ31 alloy. On the other hand, AZ31 alloy shows the development of intense shear bands during stretch forming, and these shear bands act as crack propagating paths, limiting the stretch formability of AZ31 alloy.

Formation and Applications of Bulk Glassy Alloys in Late Transition Metal Base System

International Nuclear Information System (INIS)

Inoue, Akihisa; Shen Baolong

2006-01-01

This paper reviews our recent results of the formation, fundamental properties, workability and applications of late transition metal (LTM) base bulk glassy alloys (BGAs) developed since 1995. The BGAs were obtained in Fe-(Al,Ga)-(P,C,B,Si), Fe-(Cr,Mo)-(C,B), Fe-(Zr,Hf,Nb,Ta)-B, Fe-Ln-B(Ln=lanthanide metal), Fe-B-Si-Nb and Fe-Nd-Al for Fe-based alloys, Co-(Ta,Mo)-B and Co-B-Si-Nb for Co-based alloys, Ni-Nb-(Ti,Zr)-(Co,Ni) for Ni-based alloys, and Cu-Ti-(Zr,Hf), Cu-Al-(Zr,Hf), Cu-Ti-(Zr,Hf)-(Ni,Co) and Cu-Al-(Zr,Hf)-(Ag,Pd) for Cu-based alloys. These BGAs exhibit useful properties of high mechanical strength, large elastic elongation and high corrosion resistance. In addition, Fe- and Co-based glassy alloys have good soft magnetic properties which cannot be obtained for amorphous and crystalline type magnetic alloys. The Fe- and Ni-based BGAs have already been used in some application fields. These LTM base BGAs are promising as new metallic engineering materials

Study On Nanohardness Of Phases Occurring In ZnAl22Cu3 And ZnAl40Cu3 Alloys

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Michalik R.

2015-06-01

Full Text Available Zn-Al alloys are mainly used due to their high tribological and damping properties. A very important issue is determination of the hardness of the phases present in the Zn-Al-Cu alloys. Unfortunately, in literature there is lack of studies on the hardness of the phases present in the alloys Zn-Al-Cu. The aim of this research was to determine the hardness of the phases present in the ZnAl22Cu3Si and ZnAl40Cu3Si alloys. The scope of the research included examination of the structure, chemical composition of selected micro-regions and hardness of phases present in the examined alloys. The research carried out has shown, that CuZn4 phase is characterized by a similar hardness as the hardness of the interdendritic areas. The phases present in the structure of ZnAl40Cu3 and ZnAl22Cu3 alloys after soaking at the temperature of 185 °C are characterized by lower hardness than the phase present in the structure of the as-cast alloys.

Nickel base alloys

International Nuclear Information System (INIS)

Gibson, R.C.; Korenko, M.K.

1980-01-01

Nickel based alloy, the characteristic of which is that it mainly includes in percentages by weight: 57-63 Ni, 7-18 Cr, 10-20 Fe, 4-6 Mo, 1-2 Nb, 0.2-0.8 Si, 0.01-0.05 Zr, 1.0-2.5 Ti, 1.0-2.5 Al, 0.02-0.06 C and 0.002-0.015 B. The aim is to create new nickel-chromium alloys, hardened in a solid solution and by precipitation, that are stable, exhibit reduced swelling and resistant to plastic deformation inside the reactor. These alloys of the gamma prime type have improved mechanical strengthm swelling resistance, structural stability and welding properties compared with Inconel 625 [fr

Work hardening characteristics in Al base alloys with 12.6 and 45 wt.% Zn

International Nuclear Information System (INIS)

Abd El-Salam, F.; Mostafa, M.M.; Wahab, L.A.; Mostafa, M.T.; Abd El-Aziz, Sh.M.

2008-01-01

The stress-strain curves were obtained for Al-Zn alloys of 12.6 wt.% Zn (alloy I) and 45 wt.% Zn (alloy II) with elements of purity (99.99). The monotonic shift of these curves towards lower flow stress and higher ductility was interrupted at the transformation temperatures 483 K (alloy I) and both 543, 603 K (alloy II). By increasing deformation temperature, Young's modulus, Y, yield and fracture stresses, σ y and σ f , respectively, fracture time, t f , the coefficient of parabolic work hardening, χ, decreased while fracture strain, ε f , and dislocation slip distance, L, increased. From the obtained X-rays diffraction patterns the lattice strain, ε, crystallite size, η, and dislocation density, ρ, were obtained at different deformation temperatures around transformation

Effect of Si addition on the glass-forming ability of a NiTiZrAlCu alloy

International Nuclear Information System (INIS)

Liang, W.Z.; Shen, J.; Sun, J.F.

2006-01-01

The effect of Si addition on the glass-forming ability (GFA) of a NiTiZrAlCu alloy was investigated by using differential scanning calorimetry (DSC), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The maximum diameter of glassy rods increased from 0.5 mm for the Ni 42 Ti 20 Zr 25 Al 8 Cu 5 alloy (the base alloy) to 2.5 mm for the Ni 42 Ti 20 Zr 21.5 Al 8 Cu 5 Si 3.5 alloy and to 3 mm for the Ni 42 Ti 19 Zr 22.5 Al 8 Cu 5 Si 3.5 alloy, when prepared by using the copper mould casting. The GFA of the alloys can be assessed by the reduced glass transition temperature T rg (=T g /T l ) and a newly proposed parameter, δ(=T x /T l - T g ). An addition of a proper amount of Si and a minor substitution of Ti with Zr can enhance the GFA of the base alloy by suppressing the formation of primary Ni(TiZr) and (TiZr)(CuAl) 2 phases and inducing the composition close to eutectic

Nonequilibrium synthesis of Nb-Al alloys by laser processing

International Nuclear Information System (INIS)

Tewari, S.K.; Mazumder, J.

1993-01-01

The technique of laser surface modification provides a unique means of synthesizing novel nonequilibrium materials in near net shape. Claddings of several NbAl 3 alloys with Ti, B and Hf as a ternary alloy addition were prepared using a CW CO 2 laser. Isothermal oxidation behavior of the clads were examined in air. Oxidation tests at 800, 1,200 and 1,400 C. Alternating layers of alumina and NbAlO 4 were not observed in any of the samples as reported in literature for conventionally processed NbAl 3 oxidized under similar conditions. The parabolic rate constants for all the alloys, except 0 B, were comparable to that for isothermal oxidation of β-NiAl, at 1,200 and 1,400 C in 0.1 atm oxygen, which is a known alumina former. Ternary alloying additions for improved oxidation resistance at 1,400 C accompanied with improved ductility were identified

Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

Science.gov (United States)

Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

2003-01-01

The objective of this viewgraph representation is to evaluate the effects of thermal exposure on the mechanical properties of both production mature and developmental Al-Li alloys. The researchers find for these alloys, the data clearly shows that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a signficant deficit in mechanical properties at higher exposure temperatures in all cases. Topics considered include: Al-Li alloys composition, key characteristics of Al-Li alloys and thermal exposure matrix.

Nanoindentation of Electropolished FeCrAl Alloy Welds

Energy Technology Data Exchange (ETDEWEB)

Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-13

The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

Quantifying the strain-induced dissolution of precipitates in Al alloy microstructures using nuclear magnetic resonance

International Nuclear Information System (INIS)

Hutchinson, C.R.; Loo, P.T.; Bastow, T.J.; Hill, A.J.; Costa Teixeira, J. da

2009-01-01

Nuclear magnetic resonance (NMR) has been used for the first time to directly monitor the dynamic partitioning of Cu atoms from shearable precipitates into the solid solution as a function of straining at room temperature in two Al-Cu-based alloys. Al-3Cu-0.05Sn (wt.%) and Al-2.5Mg-1.5Cu (wt.%) alloys were heat-treated to provide a fine distribution of ∼5 nm Guinier-Preston (GP) zones and <1 nm Guinier-Preston-Bagaryatsky (GPB) zones, respectively, and were then subjected to rolling strains up to 100%. It is shown that in the Al-Cu-0.05Sn alloy, strains up to ∼40% can pump solute from the ∼5 nm GP zones back into solid solution for the temperature and strain-rate of deformation employed here. In the case of the Al-Cu-Mg alloy, no dissolution of the GPB zones is observed. A simple model for the strain-induced dissolution of the shearable precipitates is given and compared with the experimental results. The dependence of the Cu repartitioning process on the precipitate size is emphasized. These observations and modeling give guidelines for the design of Al-Cu-based alloys to exploit the dynamic interplay of strain-induced Cu partitioning between metastable states, e.g. solid solution and GP (or GPB) zones, for tailoring ultimate mechanical properties. It is proposed that this strain-induced phase transformation is a form of dynamically responding microstructure that can be employed to obtain aluminum alloys with well-designed microstructures.

The effect of TiB2 reinforcement on the mechanical properties of an Al-Cu-Li alloy-based metal-matrix composite

Science.gov (United States)

Langan, T. J.; Pickens, J. R.

1991-01-01

Weldalite 049, an Al-base Cu-Li-Mg-Ag-Zr alloy, achieves 700 MPa tensile strengths in the near-peak-aged temper in virtue of the nucleation of a T(1)-type platelike strengthening precipitate. Attention is presently given to the possibility that the alloy's modulus could be further increased through the addition of high-modulus TiB2 particles, using the 'XD' process, due to TiB2's good wettability with liquid Al. An 8-percent modulus increase is obtained with 4 vol pct TiB2.

Microstructure and mechanical properties of cast Ti-47Al-2Cr-2Nb alloy melted in various crucibles

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Wang Ligang

2012-02-01

Full Text Available The main factors limiting the mass production of TiAl-based components are the high reactivity of TiAl-based alloys with the crucible or mould at high temperature. In this work, various crucibles (e.g. CaO, Y2O3 ceramic crucibles and water-cooled copper crucible were used to fabricate the Ti-47Al-2Cr-2Nb alloy in a vacuum induction furnace. The effects of crucible materials and melting parameters on the microstructure and mechanical properties of the alloy were analyzed by means of microstructure observation, chemical analysis, tensile test and fracture surface observation. The possibilities of melting TiAl alloys in crucibles made of CaO and Y2O3 refractory materials were also discussed.

Preliminary Analysis of the General Performance and Mechanical Behavior of Irradiated FeCrAl Base Alloys and Weldments

Energy Technology Data Exchange (ETDEWEB)

Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-09-30

The iron-based, iron-chromium-aluminum (FeCrAl) alloys are promising, robust materials for deployment in current and future nuclear power plants. This class of alloys demonstrates excellent performance in a range of environments and conditions, including high-temperature steam (>1000°C). Furthermore, these alloys have the potential to have prolonged survival under loss-of-coolant accident (LOCA) conditions compared to the more traditional cladding materials that are either Zr-based alloys or austenitic steels. However, one of the issues associated with FeCrAl alloys is cracking during welding. The present project investigates the possibility of mitigating welding-induced cracking via alloying and precise structure control of the weldments; in the frame work of the project, several advanced alloys were developed and are being investigated prior to and after neutron irradiation to provide insight into the radiation tolerance and mechanical performance of the weldments. The present report provides preliminary results on the post-irradiation characterization and mechanical tests performed during United States Fiscal Year (FY) 2016. Chapter 1 provides a general introduction, and Chapter 2 describes the alloy compositions, welding procedure, specimen geometry and manufacturing parameters. Also, a brief discussion of the irradiation at the High Flux Isotope Reactor (HFIR) is provided. Chapter 3 is devoted to the analysis of mechanical tests performed at the hot cell facility; tensile curves and mechanical properties are discussed in detail focusing on the irradiation temperature. Limited fractography results are also presented and analyzed. The discussion highlights the limitations of the testing within a hot cell. Chapter 4 underlines the advantages of in-situ testing and discusses the preliminary results obtained with newly developed miniature specimens. Specimens were moved to the Low Activation Materials Development and Analysis (LAMDA) laboratory and prepared for

Evaluation of porosity in Al alloy die castings

Directory of Open Access Journals (Sweden)

M. Říhová

2012-01-01

Full Text Available Mechanical properties of an Al-alloy die casting depend significantly on its structural properties. Porosity in Al-alloy castings is one of the most frequent causes of waste castings. Gas pores are responsible for impaired mechanical-technological properties of cast materials. On the basis of a complex evaluation of experiments conducted on AlSi9Cu3 alloy samples taken from the upper engine block which was die- cast with and without local squeeze casting it can be said that castings manufactured without squeeze casting exhibit maximum porosity in the longitudinal section. The area without local squeeze casting exhibits a certain reduction in mechanical properties and porosity increased to as much as 5%. However, this still meets the norms set by SKODA AUTO a.s.

Structure and corrosion behavior of sputter deposited cerium oxide based coatings with various thickness on Al 2024-T3 alloy substrates

Energy Technology Data Exchange (ETDEWEB)

Liu, Yuanyuan [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China); Materials Research Center, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Huang, Jiamu, E-mail: huangjiamu@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China); Claypool, James B.; Castano, Carlos E. [Materials Research Center, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); O’Keefe, Matthew J., E-mail: mjokeefe@mst.edu [Materials Research Center, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States)

2015-11-15

Highlights: • Crystalline CeO{sub 2} coatings are deposited on Al 2024-T3 alloys by magnetron sputtering. • The crystal size and internal stress both increased with the thickness of CeO{sub 2} coating. • The ∼210 nm thick coating has the highest adhesion strength to the Al alloy substrate. • The ∼900 nm thick coating increased the corrosion resistance two orders of magnitude. • CeO{sub 2} coatings provide good cathodic inhibition for Al alloys by acting as physical barriers. - Abstract: Cerium oxide based coatings from ∼100 to ∼1400 nm in thickness were deposited onto Al 2024-T3 alloy substrates by magnetron sputtering of a 99.99% pure CeO{sub 2} target. The crystallite size of CeO{sub 2} coatings increased from 15 nm to 46 nm as the coating thickness increased from ∼100 nm to ∼1400 nm. The inhomogeneous lattice strain increased from 0.36% to 0.91% for the ∼100 nm to ∼900 nm thick coatings and slightly decreased to 0.89% for the ∼1400 nm thick coating. The highest adhesion strength to Al alloy substrates was for the ∼210 nm thick coating, due to a continuous film coverage and low internal stress. Electrochemical measurements indicated that sputter deposited crystalline CeO{sub 2} coatings acted as physical barriers that provide good cathodic inhibition for Al alloys in saline solution. The ∼900 nm thick CeO{sub 2} coated sample had the best corrosion performance that increased the corrosion resistance by two orders magnitude and lowered the cathodic current density 30 times compared to bare Al 2024-T3 substrates. The reduced defects and exposed surface, along with suppressed charge mobility, likely accounts for the improved corrosion performance as coating thickness increased from ∼100 nm to ∼900 nm. The corrosion performance decreased for ∼1400 nm thick coatings due in part to an increase in coating defects and porosity along with a decrease in adhesion strength.

Microstructure and Tensile/Corrosion Properties Relationships of Directionally Solidified Al-Cu-Ni Alloys

Science.gov (United States)

Rodrigues, Adilson V.; Lima, Thiago S.; Vida, Talita A.; Brito, Crystopher; Garcia, Amauri; Cheung, Noé

2018-03-01

Al-Cu-Ni alloys are of scientific and technological interest due to high strength/high temperature applications, based on the reinforcement originated from the interaction between the Al-rich phase and intermetallic composites. The nature, morphology, size, volume fraction and dispersion of IMCs particles throughout the Al-rich matrix are important factors determining the resulting mechanical and chemical properties. The present work aims to evaluate the effect of the addition of 1wt%Ni into Al-5wt%Cu and Al-15wt%Cu alloys on the solidification rate, macrosegregation, microstructure features and the interrelations of such characteristics on tensile and corrosion properties. A directional solidification technique is used permitting a wide range of microstructural scales to be examined. Experimental growth laws relating the primary and secondary dendritic spacings to growth rate and solidification cooling rate are proposed, and Hall-Petch type equations are derived relating the ultimate tensile strength and elongation to the primary dendritic spacing. Considering a compromise between ultimate tensile strength and corrosion resistance of the examined alloys samples from both alloys castings it is shown that the samples having more refined microstructures are associated with the highest values of such properties.

Interaction of hydrogen with an Mg-Al alloy

International Nuclear Information System (INIS)

Andreasen, A.; Sorensen, M.B.; Burkarl, R.; Moller, B.; Molenbroek, A.M.; Pedersen, A.S.; Andreasen, J.W.; Nielsen, M.M.; Jensen, T.R.

2005-01-01

The interaction of hydrogen with an Mg-Al alloy pre-exposed to air have been studied with in situ time resolved X-ray powder diffraction. Phase fractions as a function of time are derived from series of consecutive diffraction patterns allowing kinetic analysis. The apparent activation energy for dehydrogenation of the Mg-Al alloy is found to be 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg. It is suggested that the addition of Al improves the resistance towards oxygen contamination

Strain and strain-rate hardening characteristics of a superplastic Al-Li-Cu-Zr alloy

International Nuclear Information System (INIS)

Ash, B.A.; Hamilton, C.H.

1988-01-01

A number of alloys based on the composition of Al-Li-Zr have been shown to be superplastic under at least one of two different microstructural conditions: 1. fully recrystallized to a fine, stable grain size, and 2. warm- or cold-worked and unrecrystallized prior to superplastic deformation. For the latter case, static recrystallization was impaired by the presence of fine Al 3 Zr particles, and dynamic recrystallization was observed to occur during superplastic deformation in which the heavily worked microstructure evolved into a fine grained fully recrystallized microstructure. This process is observed in other Al alloys as well, such as the Al-Cu-Zr alloys (Supral alloys), Al-Zn-Mg-Zr alloys, Al-Mn-Zr alloys, and Al-Mg-Mn alloys where the dynamic recrystallization has been suggested to be a continuous reaction in which recrystallization occurs by a gradual and homogeneous process during deformation rather than by the more common nucleation and growth process. Experimental observations of continuous recrystallization show development of a subgrain structure which coarsens continuously while deformation proceeds, with a concurrent increase in the misorientation angle between adjacent subgrains which ultimately approaches that of a high-angle boundary, characteristic of a fully- recrystallized microstructure. During the first 50 to 300% deformation, the microstructure evolves from the heavily worked to a fully recrystallized microstructure after which the fully recrystallized microstructure apparently exhibits the typical micro-grain superplastic characteristics. Superplasticity under continuous dynamic recrystallization is of interest both from scientific and technological standpoints since the rates at which superplastic deformation can be obtained are often higher than those for the fully recrystallized microstructures

Moessbauer and transport studies of amorphous and icosahedral Zr-Ni-Cu-Ag-Al alloys

International Nuclear Information System (INIS)

Stadnik, Z.M.; Rapp, O.; Srinivas, V.; Saida, J.; Inoue, A.

2002-01-01

The alloy Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 in the amorphous and icosahedral states, and the bulk amorphous alloy Zr 65 Al 7.5 Ni 10 Cu 7.5 Ag 10 , have been studied with 57 Fe Moessbauer spectroscopy, electrical resistance and magnetoresistance techniques. The average quadrupole splitting in both alloys decreases with temperature as T 3/2 . The average quadrupole splitting in the icosahedral alloy is the largest ever reported for a metallic system. The lattice vibrations of the Fe atoms in the amorphous and icosahedral alloys are well described by a simple Debye model, with the characteristic Moessbauer temperatures of 379(29) and 439(28) K, respectively. Amorphous alloys Zr 65 Al 7. )5Ni 10 Cu 7.5 Ag 10 and Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 have been found to be superconducting with the transition temperature, T c , of about 1.7 K. The magnitude of Tc and the critical field slope at Tc are in agreement with previous work on Zr-based amorphous superconductors, while the low-temperature normal state resistivity is larger than typical results for binary and ternary Zr-based alloys. The resistivity of icosahedral Zr 65 Al 7.5 Ni 10 Cu 7.3 Fe 0.2 Ag 10 is larger than that for the amorphous ribbon of the same composition, as inferred both from direct measurements on the ribbons and from the observed magnetoresistance. However the icosahedral sample is non-superconducting in the measurement range down to 1.5 K. The results for the resistivity and the superconducting T c both suggest a stronger electronic disorder in the icosahedral phase than in the amorphous phase. (author)

Strength and ductility of Ni3Al alloyed with boron and substitutional elements

International Nuclear Information System (INIS)

Ishikawa, K.; Aoki, K.; Masumoto, T.

1995-01-01

The effect of simultaneous alloying of boron (B) and the substitutional elements M on mechanical properties of Ni 3 Al was investigated by the tensile test at room temperature. The yield strength of Ni 3 Al+B increases by alloying with M except for Fe and Ga. In particular, it increases by alloying with Hf, Nb, W, Ta, Pd and Si. The fracture strength of Ni 3 Al+B increases by alloying with Pd, Ga, Si and Hf, but decreases with the other elements. Elongation of Ni 3 Al+B increases by alloying with Ga, Fe and Pd, but decreases with other elements. Hf and Pd is the effective element for the increase of the yield strength and the fracture strength of Ni 3 Al+B, respectively. Alloying with Hf leads to the increases of the yield strength and the fracture strength of Ni 3 Al+B, but to the lowering of elongation. On the other hand, alloying with Pd improves all mechanical properties, i.e. the yield strength, the fracture strength and elongation. On the contrary, alloying with Ti, V and Co leads to the lowering of mechanical properties of Ni 3 Al+B. The reason why ductility of Ni 3 Al+B is reduced by alloying with some elements M is discussed

Quality analysis of the Al-Si-Cu alloy castings

Directory of Open Access Journals (Sweden)

L.A. Dobrzański

2007-04-01

Full Text Available The developed design methodologies both the material and technological ones will make it possible to improve shortly the quality of materials from the light alloys in the technological process, and the automatic process flow correction will make the production cost reduction possible, and - first of all - to reduce the amount of the waste products. Method was developed for analysis of the casting defects images obtained with the X-ray detector analysis of the elements made from the Al-Si-Cu alloys of the AC-AlSi7Cu3Mg type as well as the method for classification of casting defects using the artificial intelligence tools, including the neural networks; the developed method was implemented as software programs for quality control. Castings were analysed in the paper of car engine blocks and heads from the Al-Si-Cu alloys of the AC-AlSi7Cu3Mg type fabricated with the “Cosworth” technological process. The computer system, in which the artificial neural networks as well as the automatic image analysis methods were used makes automatic classification possible of defects occurring in castings from the Al-Si-Cu alloys, assisting and automating in this way the decisions about rejection of castings which do not meet the defined quality requirements, and therefore ensuring simultaneously the repeatability and objectivity of assessment of the metallurgical quality of these alloys.

Hot-tearing of multicomponent Al-Cu alloys based on casting load measurements in a constrained permanent mold

Energy Technology Data Exchange (ETDEWEB)

Sabau, Adrian S [ORNL; Mirmiran, Seyed [Fiat Chrysler Automobiles North America; Glaspie, Christopher [Fiat Chrysler Automobiles North America; Li, Shimin [Worcester Polytechnic Institute (WPI), MA; Apelian, Diran [Worcester Polytechnic Institute (WPI), MA; Shyam, Amit [ORNL; Haynes, James A [ORNL; Rodriguez, Andres [Nemak, Garza Garcia, N.L., Mexico

2017-01-01

Hot-tearing is a major casting defect that is often difficult to characterize, especially for multicomponent Al alloys used for cylinder head castings. The susceptibility of multicomponent Al-Cu alloys to hot-tearing during permanent mold casting was investigated using a constrained permanent mold in which the load and displacement was measured. The experimental results for hot tearing susceptibility are compared with those obtained from a hot-tearing criterion based temperature range evaluated at fraction solids of 0.87 and 0.94. The Cu composition was varied from approximately 5 to 8 pct. (weight). Casting experiments were conducted without grain refining. The measured load during casting can be used to indicate the severity of hot tearing. However, when small hot-tears are present, the load variation cannot be used to detect and assess hot-tearing susceptibility.

Hardening mechanisms of spray formed Al-Zn-Mg-Cu alloys with scandium and other elemental additions

International Nuclear Information System (INIS)

Sharma, M.M.; Amateau, M.F.; Eden, T.J.

2006-01-01

The hardening mechanisms in spray formed Al-Zn-Mg-Cu alloys with additions of chromium, zinc and scandium were studied. The microstructure of the spray formed alloys was analyzed by transmission electron microscopy. A range of tensile strengths were achieved, and varied based on elemental additions, and second phase particle strengthening. To explain the significantly higher strength in one alloy with scandium, theoretical results due to the yield stress of Al-Zn-Mg-Cu alloys as a function of volume fraction and precipitate particle size, were compared to experimental data. Both the possibilities of coherency and order strengthening are examined. The significant additional hardening achieved in the alloy with scandium is attributed to small ordered particles of Al 3 Sc, which precipitated during aging

Modeling of TiAl Alloy Grating by Investment Casting

Directory of Open Access Journals (Sweden)

Yi Jia

2015-12-01

Full Text Available The investment casting of TiAl alloys has become the most promising cost-effective technique for manufacturing TiAl components. This study aimed to investigate a series of problems associated with the investment casting of TiAl alloys. The mold filling and solidification of this casting model were numerically simulated using ProCAST. Shrinkage porosity was quantitatively predicted by a built-in feeding criterion. The results obtained from the numerical simulations were compared with experiments, which were carried out on Vacuum Skull Furnace using an investment block mold. The investment casting of TiAl grating was conducted for verifying the correctness and feasibility of the proposed method. The tensile test results indicated that, at room temperature, the tensile strength and elongation were approximately 675 MPa and 1.7%, respectively. The microstructure and mechanical property of the investment cast TiAl alloy were discussed.

Description of hypoeutectic Al-Si-Cu alloys based on their known chemical compositions

Directory of Open Access Journals (Sweden)

Djurdjevic, M. B.

2013-10-01

Full Text Available The modeling of casting processes has remained a topic of active interest for several decades, and the availability of numerous software packages on the market is a good indication of the interest that the casting industry has in this field. Most of the data used in these software packages are directly read or estimated from the binary or multi-component phase diagrams. Unfortunately, except for binary diagrams, many of ternary or higher order phase diagrams are still not accurate enough. Having in mind that most of the aluminum binary systems are very well established, it has been tried to transfer multi-component system into one well known Al-Xi pseudo binary system (in this case the Al-Si phase diagram was chosen as a reference system. The new Silicon Equivalency (SiEQ algorithm expresses the amounts of major and minor alloying elements in the aluminum melts through an “equivalent” amount of silicon. Such a system could be used to calculate several thermo-physical and solidification characteristics of multi component as cast aluminum alloys. This provides to the model the capacity to predict the solidification characteristics of cast parts, where cooling rates are slow and the solidification process has to be known in great detail in order to avoid quality problems in the casting. This work demonstrates how the SiEQ algorithm can be used to calculate the characteristic solidification temperatures of the multicomponent Al-Si alloys as well as their latent heats and growth restriction factor. Statistical analysis of the results obtained for a wide range of alloy chemical compositions shows a very good correlation with the experimental data and the SiEQ calculations. The same mathematical approach might be applied for other metallic systems such as iron and magnesium, using carbon equivalency for ferrous systems and aluminum equivalency for magnesium multi-component alloys.La modelización de los procesos de fundición ha sido un tópico de

Ductile shape memory alloys of the Cu-Al-Mn system

International Nuclear Information System (INIS)

Kainuma, R.; Takahashi, S.; Ishida, K.

1995-01-01

Cu-Al-Mn shape memory alloys with enhanced ductility have been developed by decreasing the degree of order in the β parent phase. Cu-Al-Mn alloys with Al contents lower than 18% exhibit good ductility with elongations of about 15% and excellent cold-workability arising from a lower degree of order in the Heusler (L21) β 1 parent phase, without any loss in their shape memory behavior. In this paper the mechanical and shape memory characteristics, such as the cold-workability, the Ms temperatures, the shape memory effect and the pseudo-elasticity of such ductile Cu-Al-Mn alloys are presented. (orig.)

Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys

Science.gov (United States)

Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

2015-03-01

Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary β and Cu-Al δ phases at 450-550°C; this was followed by β-Sn, and, finally, Cu6Sn5 and Cu-Al γ1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

Modeling of TiAl Alloy Grating by Investment Casting

OpenAIRE

Yi Jia; Shulong Xiao; Jing Tian; Lijuan Xu; Yuyong Chen

2015-01-01

The investment casting of TiAl alloys has become the most promising cost-effective technique for manufacturing TiAl components. This study aimed to investigate a series of problems associated with the investment casting of TiAl alloys. The mold filling and solidification of this casting model were numerically simulated using ProCAST. Shrinkage porosity was quantitatively predicted by a built-in feeding criterion. The results obtained from the numerical simulations were compared with experimen...

Effect of alumina on grain refinement of Al-Si hypereutectic alloys

Science.gov (United States)

Majhi, J.; Sahoo, S. K.; Patnaik, S. C.; Sarangi, B.; Sachan, N. K.

2018-03-01

The size, volume fraction and distribution of primary as well as eutectic silicon affect the mechanical properties of the Al-Si hypereutectic alloys. It is very difficult for the simultaneous refinement and modification of primary and secondary Si particles in hypereutectic Al-Si alloys through traditional processes. This paper explores the role of γ-Al2O3 nanoparticles on Si particles in the course of solidification in hypereutectic Al-Si alloys at particular pouring temperature. The present study involves incorporation of varying contents dispersed γ-Al2O3 nanoparticles into a molten base metal during stir casting and followed by solidification. It has been reported that the synthesized composites having good interfacial bonding (wetting) between the dispersed phase and the liquid matrix was achieved in order to provide improved mechanical properties of the composite. The cast product of hypereutectic Al-16Si alloy with the reinforcement of nanoparticles, illustrated a significant improvement in both wear behaviour and hardness. The dry sliding wear test has been performed on a group of specimens with varying parameters (different loads and sliding velocities) in a pin on disc wear testing machine. Moreover, the wear rate and specific wear rate also affected in different load and different sliding velocities. However in XRD analysis of the samples, the enhancement of wear resistance as well as hardness was due to the formation of brittle phases like SiO2, Al2O3 and Al-rich intermetallic compounds. The hardness value of the materials increases nearly 6% in addition to increase in the density of only 0.8%. As per literature, the large plate eutectic Si particles were modified in to the fine core particles and it acquires enough potential for various applications.

Design of high-temperature high-strength Al-Ti-V-Zr alloys

International Nuclear Information System (INIS)

Lee, H.M.

1990-01-01

This paper reports that it seems plausible to develop high-strength Al-base alloys useful up to 698K in view of the behavior of nickel base superalloys which resist degradation of mechanical properties to 75 pct of their absolute melting temperature. For high temperature Al alloys, the dispersed hardening phase must not undergo phase transformation to an undesirable phase during long time exposure at the temperature of interest. An additional factor to be considered is the stability of the hardening phase with respect to Ostwald ripening. This coarsening resistance is necessary so that the required strength level can be maintained after the long-time service at high temperatures. The equilibrium crystal structures of Al 3 Ti, Al 3 V and Al 3 Zr are tetragonal D0 22 , D0 22 and D0 23 , respectively. At the temperatures of interest, around 698K, vanadium and titanium are mutually substitutable in the form of Al 3 (Ti, V). Much of titanium and vanadium can be substituted for zirconium in the D0 23 - type Al 3 Zr compound, creating Al 3 (Ti, Zr) and Al 3 (V, Zr), respectively. In particular, it has been reported that fcc L1 2 -structured Al 3 M dispersoids form in the rapidly solidified Al-V-Zr and Al-Ti-Zr systems and both L1 2 and D0 23 -structured Al 3 M phases showed slow coarsening kinetics

The modification of some properties of Al-2%Mg alloy by Ti &Li alloying elements