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Sample records for alloy aluminum solidification

  1. Advanced powder metallurgy aluminum alloys via rapid solidification technology

    Science.gov (United States)

    Ray, R.

    1984-01-01

    Aluminum alloys containing 10 to 11.5 wt. pct. of iron and 1.5 to 3 wt. pct. of chromium using the technique of rapid solidification powder metallurgy were studied. Alloys were prepared as thin ribbons (.002 inch thick) rapidly solidified at uniform rate of 10(6) C/second by the melt spinning process. The melt spun ribbons were pulverized into powders (-60 to 400 mesh) by a rotating hammer mill. The powders were consolidated by hot extrusion at a high reduction ratio of 50:1. The powder extrusion temperature was varied to determine the range of desirable processing conditions necessary to yield useful properties. Powders and consolidated alloys were characterized by SEM and optical metallography. The consolidated alloys were evaluated for (1) thermal stability, (2) tensile properties in the range, room temperature to 450 F, and (3) notch toughness in the range, room temperature to 450 F.

  2. Solidification crack susceptibility of aluminum alloy weld metals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The susceptibilities of the three aluminum alloys to solidification crack were studied with trans-varestraint tests and tensile tests at elevated temperature. Their metallurgical characteristics, morphologies of the fractured surface and dynamic cracking behaviors at elevated temperature were analyzed with a series of micro-analysis methods. The results show that dynamic cracking models can be classified into three types. The first model has the healing effect which is called type A. The second is the one with deformation and breaking down of metal bridge, called type B. The last one is with the separation of liquid film along grain boundary, called type C.Moreover, the strain rate has different effects on crack susceptibility of aluminum alloys with different cracking models. ZL101 and 5083 alloys belong to type A and type C cracking model respectively, in which strain rate has greater effect on eutectic healing and plastic deformation of metal bridge. 6082 alloy is type B cracking model in which the strain rate has little effect on the deformation ability of the liquid film.

  3. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Ripeng Jiang

    2014-07-01

    Full Text Available The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  4. Density and solidification feeding model of vacuum counter-pressure cast aluminum alloy under grade-pressuring conditions

    OpenAIRE

    Qing-song Yan; Huan Yu; Gang Lu

    2016-01-01

    The density of vacuum counter-pressure cast aluminum alloy samples under grade-pressuring condition was studied. The effect of grade pressure difference and time on the density of aluminum alloys was discussed, and the solidification feeding model under grade-pressuring condition was established. The results indicate the grade-pressured solidification feeding ability of vacuum counter-pressure casting mainly depends on grade pressure difference and time. With the increase of grade pressure di...

  5. Advanced powder metallurgy aluminum alloys via rapid solidification technology, phase 2

    Science.gov (United States)

    Ray, Ranjan; Jha, Sunil C.

    1987-01-01

    Marko's rapid solidification technology was applied to processing high strength aluminum alloys. Four classes of alloys, namely, Al-Li based (class 1), 2124 type (class 2), high temperature Al-Fe-Mo (class 3), and PM X7091 type (class 4) alloy, were produced as melt-spun ribbons. The ribbons were pulverized, cold compacted, hot-degassed, and consolidated through single or double stage extrusion. The mechanical properties of all four classes of alloys were measured at room and elevated temperatures and their microstructures were investigated optically and through electron microscopy. The microstructure of class 1 Al-Li-Mg alloy was predominantly unrecrystallized due to Zr addition. Yield strengths to the order of 50 Ksi were obtained, but tensile elongation in most cases remained below 2 percent. The class 2 alloys were modified composition of 2124 aluminum alloy, through addition of 0.6 weight percent Zr and 1 weight percent Ni. Nickel addition gave rise to a fine dispersion of intermetallic particles resisting coarsening during elevated temperature exposure. The class 2 alloy showed good combination of tensile strength and ductility and retained high strength after 1000 hour exposure at 177 C. The class 3 Al-Fe-Mo alloy showed high strength and good ductility both at room and high temperatures. The yield and tensile strength of class 4 alloy exceeded those of the commercial 7075 aluminum alloy.

  6. Density and solidification feeding model of vacuum counter-pressure cast aluminum alloy under grade-pressuring conditions

    Directory of Open Access Journals (Sweden)

    Qing-song Yan

    2016-03-01

    Full Text Available The density of vacuum counter-pressure cast aluminum alloy samples under grade-pressuring condition was studied. The effect of grade pressure difference and time on the density of aluminum alloys was discussed, and the solidification feeding model under grade-pressuring condition was established. The results indicate the grade-pressured solidification feeding ability of vacuum counter-pressure casting mainly depends on grade pressure difference and time. With the increase of grade pressure difference, the density of all the aluminum alloy samples increases, and the trend of change in density from the pouring gate to the top location is first decreasing gradually and then increasing. In addition, in obtaining the maximum density, the optimal grade-pressuring time is different for samples with different wall thicknesses, and the solidification time when the solid volume fraction of aluminum alloy reaches about 0.65 appears to be the optimal beginning time for grade-pressuring.

  7. Numerical simulation of the aluminum alloys solidification in complex geometries

    International Nuclear Information System (INIS)

    The process of mould design in the foundry industry has been based on the intuition and experience of foundry engineers and designers. To bring the industry to a more scientific basis the design process should be integrated with scientific analysis such as heat transfer. The production by foundry techniques in influenced by the geometry configuration, which affects the solidification conditions and subsequent cooling. Numerical simulation and/or experiments make possible the selection of adequate materials, reducing cycle times and minimizing production costs. The main propose of this work is to study the heat transfer phenomena in the mould considering the phase change of the cast-part. Due to complex geometry of the mould, a block unstructured grid and a generalized curvilinear formulation engaged with the finite volume method is described and applied. Two types of boundary conditions, diffusive and Newtonian, are used and compared. The developed numerical code is tested in real case and the main results are compared with experimental data. The results showed that the solidification time is about 6 seconds for diffusive boundary conditions and 14.8 seconds for Newtonian boundary conditions. The use of the block unstructured grid in combination with a generalized curvilinear formulation works well with the finite volume method and allows the development of more efficient algorithms with better capacity to describe the part contours through a lesser number of elements

  8. Melting and Solidification Behaviour of Bi-Pb Multiphase Alloy Nanoparticles Embedded in Aluminum Matrix.

    Science.gov (United States)

    Khan, Patan Yousaf; Biswas, Krishanu

    2015-01-01

    The present investigation reports the result of the investigation on the phase transformation of biphasic Bi-Pb alloy nanoparticles embedded in the aluminum matrix. The samples are prepared by rapid solidification route involving melt spinning of Al-6 wt% (Bi55.9Pb44.1) alloy on a rotating copper wheel in an argon-filled evacuated chamber. The detailed transmission electron microscope (TEM) investigation shows presence of near cuboctahedral shaped biphasic nano-inclusions consisting of the (Bi) solid solution and β, the intermediate phase. β constitutes bulk of the nanoparticle with (Bi) forming the cap. Both the phases bear distinct orientation relationship with the matrix. The compositional analysis indicates substantial increase in solid solubilities of Pb in the (Bi) and Bi in the β-phases as compared to the as-cast sample. Differential scanning calorimetric (DSC) studies indicate substantial superheating (16.4 K) of the embedded nanoparticles with appearance of sharp melting peak. The solidification is observed to be diffused, taking place over a large temperature range (344.5 K to 332 K). The in situ heating stage experiments carried out in TEM indicate formation of core shell morphology during heating with β forming the shell around (Bi). The melting starts from Al/β/(Bi) triple point and then the liquid spreads along matrix-particle interface. The solidification occurs in eutectic manner. PMID:26328350

  9. Interplay among solidification, microstructure, residual strain and hot tearing in B206 aluminum alloy

    International Nuclear Information System (INIS)

    Hot tearing is a complex phenomenon attributed to alloy solidification, microstructure and stress/strain development within a casting. In this research, the conditions associated with the formation of hot tears in B206 aluminum alloy were investigated. Neutron diffraction strain mapping was carried out on three B206 castings with varying levels of titanium (i.e. unrefined, 0.02 and 0.05 wt%). Titanium additions effectively reduced grain size and transformed grain morphology from coarse dendrites to fine globular grains. Further, thermal analysis suggested that grain refinement delayed the onset of dendrite coherency in B206 and therefore enhanced the duration of bulk liquid metal feeding for the refined casting conditions. As a result, the interactive effects of such factors resulted in a more uniform distribution of strain, and subsequent higher resistance to hot tearing for the grain refined castings

  10. Aluminum alloy weldability. Identification of weld solidification cracking mechanisms through novel experimental technique and model development

    Energy Technology Data Exchange (ETDEWEB)

    Coniglio, Nicolas

    2008-07-01

    The objective of the present thesis is to make advancements in understanding solidification crack formation in aluminum welds, by investigating in particular the aluminum 6060/4043 system. Alloy 6060 is typical of a family of Al-Mg-Si extrusion alloys, which are considered weldable only when using an appropriate filler alloy such as 4043 (Al-5Si). The effect of 4043 filler dilution (i.e. weld metal silicon content) on cracking sensitivity and solidification path of Alloy 6060 welds are investigated. Afterwards, cracking models are developed to propose mechanisms for solidification crack initiation and growth. Cracking Sensitivity. Building upon the concept that silicon improves weldability and that weldability can be defined by a critical strain rate, strain rate-composition combinations required for solidification crack formation in the Al- 6060/4043 system were determined using the newly developed Controlled Tensile Weldability (CTW) test utilizing local strain extensometer measurements. Results, presented in a critical strain rate - dilution map, show a crack - no crack boundary which reveals that higher local strain rates require higher 4043 filler dilution to avoid solidification cracking when arc welding Alloy 6060. Using the established crack - no crack boundary as a line of reference, additional parameters were examined and their influence on cracking characterized. These parameter influences have included studies of weld travel speed, weld pool contaminants (Fe, O, and H), and grain refiner additions (TiAl{sub 3} + Boron). Each parameter has been independently varied and its effect on cracking susceptibility quantified in terms of strain rate - composition combinations. Solidification Path. Solidification path of the Al-6060/4043 system was characterized using thermal analysis and phase identification. Increasing 4043 filler dilution from 0 to 16% in Alloy 6060 arc welds resulted in little effect on thermal arrests and microstructure, no effect on

  11. Effect of centrifugal counter-gravity casting on solidification microstructure and mechanical properties of A357 aluminum alloy

    OpenAIRE

    Li Xinlei; Hao Qitang; Miao Xiaochuan

    2014-01-01

    To investigate the influence of Centrifugal Counter-gravity Casting (C3) process on the solidification microstructure and mechanical properties of the casting, A357 aluminum alloy samples were produced by different process conditions under C3. The results show that C3 has better feeding capacity compared with the vacuum suction casting; and that the mechanical vibration and the convection of melts formed at the centrifugal rotation stage suppress the growth of dendrites, subsequently resultin...

  12. The effect of solidification rate on the growth of small fatigue cracks in a cast 319-type aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Caton, M.J.; Jones, J.W.; Boileau, J.M.; Allison, J.E.

    1999-12-01

    A study was conducted to investigate the effect of solidification rate on the growth behavior of small fatigue cracks in a 319-type aluminum alloy, a common Al-Si-Cu alloy used in automotive castings. Fatigue specimens were taken from cast material that underwent a hot isostatic pressing (HIP) process in order to eliminate shrinkage pores and to facilitate the observation of surface-initiated cracks by replication. Naturally initiated surface cracks ranging in length from 17 {micro}m to 2 mm were measured using a replication technique. Growth rates of the small cracks were calculated as a function of the elastic stress-intensity-factor range ({Delta}K). Long-crack growth-rate data (10 mm {le} length {le} 25 mm) were obtained from compact-tension (CT) specimens, and comparison to the small-crack data indicates the existence of a significant small-crack effect in this alloy. The solidification rate is shown to have a significant influence on small-crack growth behavior, with faster solidification rates resulting in slower growth rates at equivalent {Delta}K levels. A stress-level effect is also observed for both solidification rates, with faster growth rates occurring at higher applied-stress amplitudes at a given {Delta}K. A crack-growth relation proposed by Nisitani and others is modified to give reasonable correlation of small-crack growth data to different solidification rates and stress levels.

  13. The effect of solidification rate on the growth of small fatigue cracks in a cast 319-type aluminum alloy

    Science.gov (United States)

    Caton, M. J.; Jones, J. Wayne; Boileau, J. M.; Allison, J. E.

    1999-12-01

    A study was conducted to investigate the effect of solidification rate on the growth behavior of small fatigue cracks in a 319-type aluminum alloy, a common Al-Si-Cu alloy used in automotive castings. Fatigue specimens were taken from cast material that underwent a hot isostatic pressing (HIP) process in order to eliminate shrinkage pores and to facilitate the observation of surface-initiated cracks by replication. Naturally initiated surface cracks ranging in length from 17 µm to 2 mm were measured using a replication technique. Growth rates of the small cracks were calculated as a function of the elastic stress-intensity-factor range (Δ K). Long-crack growth-rate data (10 mm≤length≤25 mm) were obtained from compact-tension (CT) specimens, and comparison to the small-crack data indicates the existence of a significant small-crack effect in this alloy. The solidification rate is shown to have a significant influence on small-crack growth behavior, with faster solidification rates resulting in slower growth rates at equivalent Δ K levels. A stress-level effect is also observed for both solidification rates, with faster growth rates occurring at higher applied-stress amplitudes at a given Δ K. A crack-growth relation proposed by Nisitani and others is modified to give reasonable correlation of small-crack growth data to different solidification rates and stress levels.

  14. Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process

    International Nuclear Information System (INIS)

    The crystal orientation characteristics of cast Al–Si, Al–Cu and Al–Mg alloys produced by a unidirectional solidification process are examined. Two distinct crystal orientation patterns are observed: uniform and random formation. A uniform crystal orientation is created by columnar growth of α-Al dendrites in the alloys with low proportions of alloying element, e.g., the Al–Si alloy (with Si <12.6%) and the Al–Cu and Al–Mg alloys (with Cu and Mg <2%). A uniformly organized crystal orientation with [100] direction is created by columnar growth of α-Al dendrites. With increasing proportion of alloying element (>2% Cu or Mg), the uniform crystal orientations collapse in the Al–Cu and Al–Mg alloys, owing to interruption of the columnar α-Al dendrite growth as a result of different dynamics of the alloying atoms and the creation of a core for the eutectic phases. For the hypo-eutectic Al–Si alloys, a uniform crystal orientation is obtained. In contrast, a random orientation can be detected in the hyper-eutectic Al–Si alloy (15% Si), which results from interruption of the growth of the α-Al dendrites due to precipitation of primary Si particles. There is no clear effect of crystal formation on ultimate tensile strength (UTS), whereas crystal orientation does influence the material ductility, with the alloys with a uniform crystal orientation being elongated beyond their UTS points and with necking occurring in the test specimens. In contrast, the alloys with a nonuniform crystal orientation are not elongated beyond their UTS points

  15. Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process

    Energy Technology Data Exchange (ETDEWEB)

    Okayasu, Mitsuhiro, E-mail: mitsuhiro.okayasu@utoronto.ca; Takeuchi, Shuhei

    2015-05-01

    The crystal orientation characteristics of cast Al–Si, Al–Cu and Al–Mg alloys produced by a unidirectional solidification process are examined. Two distinct crystal orientation patterns are observed: uniform and random formation. A uniform crystal orientation is created by columnar growth of α-Al dendrites in the alloys with low proportions of alloying element, e.g., the Al–Si alloy (with Si <12.6%) and the Al–Cu and Al–Mg alloys (with Cu and Mg <2%). A uniformly organized crystal orientation with [100] direction is created by columnar growth of α-Al dendrites. With increasing proportion of alloying element (>2% Cu or Mg), the uniform crystal orientations collapse in the Al–Cu and Al–Mg alloys, owing to interruption of the columnar α-Al dendrite growth as a result of different dynamics of the alloying atoms and the creation of a core for the eutectic phases. For the hypo-eutectic Al–Si alloys, a uniform crystal orientation is obtained. In contrast, a random orientation can be detected in the hyper-eutectic Al–Si alloy (15% Si), which results from interruption of the growth of the α-Al dendrites due to precipitation of primary Si particles. There is no clear effect of crystal formation on ultimate tensile strength (UTS), whereas crystal orientation does influence the material ductility, with the alloys with a uniform crystal orientation being elongated beyond their UTS points and with necking occurring in the test specimens. In contrast, the alloys with a nonuniform crystal orientation are not elongated beyond their UTS points.

  16. Effect of Holding Time Before Solidification on Double-Oxide Film Defects and Mechanical Properties of Aluminum Alloys

    Science.gov (United States)

    El-Sayed, Mahmoud Ahmed; Salem, Hanadi A. G.; Kandeil, Abdelrazek Youssef; Griffiths, W. D.

    2011-12-01

    Double-oxide films (bifilms) have been held responsible for the variability in mechanical properties of aluminum castings. It has been suggested that the air entrapped inside a bifilm can react with the surrounding melt, leading to its consumption, which might improve the mechanical properties of the castings. In this work the effect of holding the melt before solidification on the distribution of mechanical properties, and by implication on entrained double oxide films, was investigated for several different aluminum alloys. The Weibull moduli of plate castings were determined under tensile conditions, and their fracture surfaces were examined for evidence of oxide films. The results suggested the occurrence of two competing mechanisms during the holding treatment: (1) the consumption of air inside the bifilms by reaction with the surrounding molten metal that may lead to improvements in mechanical properties and (2) the accompanying diffusion of hydrogen into the bifilms, which would be expected to have a deleterious effect on properties.

  17. Controlled Directional Solidification of Aluminum - 7 wt Percent Silicon Alloys: Comparison Between Samples Processed on Earth and in the Microgravity Environment Aboard the International Space Station

    Science.gov (United States)

    Grugel, Richard N.; Tewari, Surendra N.; Erdman, Robert G.; Poirier, David R.

    2012-01-01

    An overview of the international "MIcrostructure Formation in CASTing of Technical Alloys" (MICAST) program is given. Directional solidification processing of metals and alloys is described, and why experiments conducted in the microgravity environment aboard the International Space Station (ISS) are expected to promote our understanding of this commercially relevant practice. Microstructural differences observed when comparing the aluminum - 7 wt% silicon alloys directionally solidified on Earth to those aboard the ISS are presented and discussed.

  18. Effect of centrifugal counter-gravity casting on solidification microstructure and mechanical properties of A357 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Li Xinlei

    2014-01-01

    Full Text Available To investigate the influence of Centrifugal Counter-gravity Casting (C3 process on the solidification microstructure and mechanical properties of the casting, A357 aluminum alloy samples were produced by different process conditions under C3. The results show that C3 has better feeding capacity compared with the vacuum suction casting; and that the mechanical vibration and the convection of melts formed at the centrifugal rotation stage suppress the growth of dendrites, subsequently resulting in the refinement of grains and the improvement of mechanical properties, density and hardness. A finer grain and higher strength can be obtained in the A357 alloy by increasing centrifugal radius and rotational speed. However, casting defects will appear near the rotational axis and the mechanical properties will decrease once the rotational speed exceeds 150 r·min-1.

  19. Casting of aluminum-copper based alloy by controlled diffusion solidification

    Directory of Open Access Journals (Sweden)

    Li Fan

    2015-03-01

    Full Text Available A quaternary alloy (Al-5.0Cu-0.35Mn-0.25Ti, wt.%, having a similar chemical component with ZL205A, was prepared using a controlled diffusion solidification (CDS process and a conventional casting process. The effect of the casting process on microstructure and hardness was investigated. The grain morphology and casting defects of the alloy prepared via the conventional casting and CDS were observed and compared at various pouring temperatures. Results show that the CDS process can alleviate the hot tearing defects and reduce the density of porosity, while getting rid of the riser that is generally used for feeding during conventional casting. Structure observations show that the grain morphology of the conventional cast alloy is mainly dendritic, and the grain size decreases when the pouring temperature is decreased, while the CDS cast alloy consists of a large number of spherical grains, which can decrease the thermal cracking tendency and segregation defect, and enhance the hardness of the alloy.

  20. Experimental Observation and Analytical Modeling of Melting and Solidification during Aluminum Alloy Repair by Turbulence Flow Casting

    Directory of Open Access Journals (Sweden)

    Muki Satya Permana

    2015-10-01

    Full Text Available This paper presents an overview on the state of the art of applicable casting technology for applications in the field of repairing aluminum alloy components. Repair process on the Al alloy sample using similar metal has been carried out to investigate the micro-structural effect. Joining occurs as a result of convection heat transfer of molten flow into the sand mold which melts the existing base metal inside the mold and subsequent solidification. The analytical model has been developed to describe aluminum alloy component repair by turbulence flow casting. The model is designed based on heat transfer principle that can handle the phenomena of heat flow. The experimental result and analytical model analyses pointed out that joint quality are greatly affected by parameters of preheating temperature and duration of molten metal flow in the mold. To obtain a desired metallurgical sound at the joint, the optimum temperature and time were adjusted in order to obtain a similarity of microstructure between filler and base metal. This model is aimed to predict the use of the process parameter ranges in order to have the optimum parameters when it is applied to the experiment. The fixed parameters are flow rate, sand ratio, and pouring temperature. The process parameters are preheating temperature and pouring time. It is concluded that analytical modeling has good agreement with the experimental result.

  1. Solidification, growth mechanisms, and associated properties of aluminum-silicon and magnesium lightweight casting alloys

    Science.gov (United States)

    Hosch, Timothy Al

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings

  2. Flow simulation and solidification phenomena of AC4CH aluminum alloy in semi-solid forging process by explicit MPS method

    Science.gov (United States)

    Regmi, Amit; Shintaku, Hiroki; Sasaki, Tsutomu; Koshizuka, Seiichi

    2015-09-01

    Semi-solid forging (SSF) is a powerful manufacturing technology to fabricate near-net shaped products in automotive industries. During SSF process, the filling behavior and solidification process of AC4CH aluminum alloy is presented in this paper. The explicit MPS method program solving Navier-Stokes equation is coupled with heat transfer and solidification has been used to predict the filling pattern and temperature distribution of semi-solid material (SSM). The non-Newtonian rheological model was used as the constitutive equation of SSM. In this study, numerical analysis of SSF was carried out in box cavity with various flange thickness (4, 8, 12 and 16 mm) and corresponding experiments were undertaken for AC4CH aluminum alloy with solid fraction less than 0.5. The numerical results of SSM filling pattern and solidification phenomena in flange were validated with the experimental results. During solidification process, flow calculation was stopped and only thermal calculation was carried out. The shrinkage defect was well predicted near the lower mid area of the box cavity with flange thickness 16 mm.

  3. Detachment of Tertiary Dendrite Arms during Controlled Directional Solidification in Aluminum - 7 wt Percent Silicon Alloys: Observations from Ground-based and Microgravity Processed Samples

    Science.gov (United States)

    Grugel, Richard N.; Erdman, Robert; Van Hoose, James R.; Tewari, Surendra; Poirier, David

    2012-01-01

    Electron Back Scattered Diffraction results from cross-sections of directionally solidified aluminum 7wt% silicon alloys unexpectedly revealed tertiary dendrite arms that were detached and mis-oriented from their parent arm. More surprisingly, the same phenomenon was observed in a sample similarly processed in the quiescent microgravity environment aboard the International Space Station (ISS) in support of the joint US-European MICAST investigation. The work presented here includes a brief introduction to MICAST and the directional solidification facilities, and their capabilities, available aboard the ISS. Results from the ground-based and microgravity processed samples are compared and possible mechanisms for the observed tertiary arm detachment are suggested.

  4. Solidification study of aluminum alloys using impulse atomization. Part I: heat transfer analysis of an atomized droplet

    International Nuclear Information System (INIS)

    Heat transfer models of molten metal droplets moving in a gas stream are used extensively to understand and improve gas atomization systems. In particular, the solidification microstructure of the metal droplets produced during atomization is closely linked with heat flow conditions. The cornerstone of these models is the calculation of the heat exchange between the droplet and gas in an environment with a high temperature gradient. To achieve this, the value of the effective heat transfer coefficient (between the gas and droplet) used in these models is obtained from semi-empirical correlations such as the Ranz-Marshall or Whitaker equations. Unfortunately, most metal atomizing conditions lie outside the experimental envelope in which these correlations were derived. Hence, the object of this paper is two fold: firstly, to develop a reliable and controlled experimental technique by which the transfer of heat from a high temperature droplet to a significantly cooler gas can be assessed and secondly, to determine the validity of both the Ranz-Marshall and Whitaker correlations under these conditions. An experimental technique was developed to conduct a series of quench tests using AA6061 aluminum and AZ91D magnesium droplets falling in a cool nitrogen and argon atmosphere, respectively. A heat transfer model was formulated to account for large droplet gas temperature gradients typically found in metallurgical processing operations. It was determined that a modified Whitaker correlation provided the best agreement with the experimental data given that the Reynolds and Prandtl numbers were evaluated at the free stream gas temperature and the gas conductivity in the Nusselt number at the droplet surface temperature. (author)

  5. Solidification shrinkage of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Feng [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China); Yang Renhui [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China)]. E-mail: yangrh2004@21cn.com; Fang Liang [Department of Applied Physics, Chongqing University, No. 174 Shazhong Road, Shapingba, Chongqing 400044 (China); Zhang Chi [Materials Interfacial Physical-Chemistry Research Institute, Chongqing Institute of Technology, No. 4 Xingsheng Road, Yangjiaping, Chongqing 400050 (China)

    2006-07-25

    Ni-Cr superalloy is widely used in casting of critical components in gas-turbine engines. Because of the significant change in density of alloy in mushy state, porosity is likely to arise in the alloy parts due to the solidification shrinkage. On the other hand, because Ni-Cr alloy is very hard and difficult to be machined, the net-shape casting of the alloy is a cheap process. Therefore, it is essential to measure the solidification shrinkage of mushy alloy for obtaining low-cost net-shape casting ingot without inner porosity. However, there have been a few reports on the solidification shrinkage of the liquid Ni-Cr alloy. In this work, the solidification shrinkage of Ni-Cr alloy was calculated by measuring its density using modified sessile drop method. It has been found that, for Ni-(0-24.53)% Cr alloys, the solidification shrinkage value fluctuates in the range of 0.91-2.02% and it tends to increase with increasing Cr concentration in 0-10% Cr. However, for Cr concentration more than 10%, the solidification shrinkage holds on a certain value of 2.00%.

  6. Changes in porosity of foamed aluminum during solidification

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to control the porosity of foamed aluminum, the changes in the porosity of foamed aluminum melt in the processes of foaming and solidification, the distribution of the porosity of foamed aluminum, and the relationship between them were studied. The results indicated that the porosity of foamed aluminum coincides well with the foaming time.

  7. Numerical simulation on melting and solidification process of aluminum-silicon alloy%铝硅合金相变材料凝固/熔化过程的数值分析

    Institute of Scientific and Technical Information of China (English)

    崔海亭; 张改; 蒋静智

    2012-01-01

    利用计算流体力学软件FLUENT的凝固/熔化模型,对双层壁圆筒内填充的铝硅合金相变材料的熔化/凝固过程进行了数值模拟,得到了在第3类边界条件下圆筒内相变材料在凝固/熔化过程中的动态温度场分布、相界面移动规律及凝固/熔化时间等,对蓄热装置的设计及实验研究提供了重要的参考价值.%By using the solidification/melting model of FLUENT software, the melting and solidification process of the aluminum-silicon alloy in a cylinder heat storage with double wall were simulated numerically. Considering the third kind of boundary condition, the dynamic temperature field distribution and the position of the phase interface change moving with time are obtained. And the melting and solidification duration time is also calculated. The results have important reference value for the numerical simulation of the phase change problem and the design of phase change energy storage device.

  8. The solidification of aluminum production waste in geopolymer matrix

    Czech Academy of Sciences Publication Activity Database

    Perná, Ivana; Hanzlíček, Tomáš

    2014-01-01

    Roč. 84, DEC 1 (2014), s. 657-662. ISSN 0959-6526 Institutional support: RVO:67985891 Keywords : aluminum waste * solidification * recycling * geopolymer Subject RIV: DM - Solid Waste and Recycling Impact factor: 3.844, year: 2014

  9. Non newtonian annular alloy solidification in mould

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, Nelson O.; Garrido, Carlos P. [Universidad de La Serena, Departamento de Ingenieria Mecanica, La Serena (Chile); Castillo, Ernesto F. [Universidad de Santiago de Chile, Departamento de Ingenieria Mecanica, Santiago (Chile)

    2012-08-15

    The annular solidification of an aluminium-silicon alloy in a graphite mould with a geometry consisting of horizontal concentric cylinders is studied numerically. The analysis incorporates the behavior of non-Newtonian, pseudoplastic (n=0.2), Newtonian (n=1), and dilatant (n=1.5) fluids. The fluid mechanics and heat transfer coupled with a transient model of convection diffusion are solved using the finite volume method and the SIMPLE algorithm. Solidification is described in terms of a liquid fraction of a phase change that varies linearly with temperature. The final results make it possible to infer that the fluid dynamics and heat transfer of solidification in an annular geometry are affected by the non-Newtonian nature of the fluid, speeding up the process when the fluid is pseudoplastic. (orig.)

  10. Die Casting Mold Design of the Thin-walled Aluminum Case by Computational Solidification Simulation

    Institute of Scientific and Technical Information of China (English)

    Young-Chan Kim; Chang-Seog Kang; Jae-Ik Cho; Chang-Yeol Jeong; Se-Weon Choi; Sung-Kil Hong

    2008-01-01

    Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among the lightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficient fluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1 mm. Therefore, in this study, thin-walled die casting of aluminum (Al-Si-Cu alloy: ALDC 12) in size of notebook computer housing and thickness of 0.8 mm was investigated by solidification simulation (MAGMA soft) and actual casting experiment (Buhler Evolution B 53D). Three different types of gating design, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thin cavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with the actual die-casting and the casting showed no casting defects and distortion.

  11. Solidification Conditions and Microstructure in Continuously Cast Aluminum

    Science.gov (United States)

    Buxmann, K.; Gold, E.

    1982-04-01

    The well-known relationship between cell size or dendrite spacing and local solidification time gives the possibility of calculating the thermal parameters of solidification from the microstructure of the as-cast product. As a basis for such calculations, the dendrite spacing of different aluminum castings (DC cast ingots of different diameters, cast in conventional and electromagnetic molds; cast strip from roll casters, belt casters, and block casters; and Properzi cast rod) has been measured through their cross sections. Based on these measurements, a qualitative discussion of the thermal conditions during the solidification of these products is given, and the influence of a variation in the casting conditions discussed.

  12. Initial stages of solidification of eutectic alloys

    International Nuclear Information System (INIS)

    The study of the various initial stages of eutectic solidification - i.e. primary nucleation, eutectic structure formation and stable growth conditions - was undertaken with various techniques including low angle neutron diffusion, in-situ electron microscopy on solidifying alloys and classical metallography. The results obtained allow to discuss the effect of metastable states during primary nucleation, of surface dendrite during eutectic nucleation and also of the crystallographic anisotropy during growth. (author)

  13. Solidification of Al alloys under electromagnetic field

    Institute of Scientific and Technical Information of China (English)

    崔建忠

    2003-01-01

    New theories and technology in the electromagnetic field were put forward about DC casting of Al alloys, including the fundamental research works, I.e, effects of the electromagnetic field on solidus and liquidus, macrosegregation of the main alloying elements, microstructures, content of alloying elements in grains and grain size after solidification under electromagnetic field, and also including a new process-DC casting under low frequency electromagnetic field(LFEMC), which can refine microstructure, eliminate macrosegregation, increase the content of alloying elements within grains, decrease the residual stress, avoid cracks and improve surface quality, and another new process-DC casting under low frequency electromagnetic vibration(LFEVC), which is a high effective method for grain refining.

  14. Study made of ductility limitations of aluminum-silicon alloys

    Science.gov (United States)

    Bailey, W. A.; Frederick, S. F.

    1967-01-01

    Study of the relation between microstructure and mechanical properties of aluminum-silicon alloys determines the cause of the variations in properties resulting from differences in solidification rate. It was found that variations in strength are a consequence of variations in ductility and that ductility is inversely proportional to dendrite cell size.

  15. Monitoring of solidification crack propagation mechanism in pulsed laser welding of 6082 aluminum

    Science.gov (United States)

    von Witzendorff, P.; Kaierle, S.; Suttmann, O.; Overmeyer, L.

    2016-03-01

    Pulsed laser sources with pulse durations in the millisecond regime can be used for spot welding and seam welding of aluminum. Seam welds are generally produced with several overlapping spot welds. Hot cracking has its origin in the solidification process of individual spot welds which determines the cracking morphology along the seam welding. This study used a monitoring unit to capture the crack geometry within individual spot welds during seam welding to investigate the conditions for initiation, propagation and healing (re-melting) of solidification cracking within overlapping pulsed laser welds. The results suggest that small crack radii and high crack angles with respect to welding direction are favorable conditions for crack healing which leads to crack-free seam welds. Optimized pulse shapes were used to produce butt welds of 0.5 mm thick 6082 aluminum alloys. Tensile tests were performed to investigate the mechanical strength in the as-welded condition.

  16. Containerless solidification of acoustically levitated Ni-Sn eutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Geng, D.L.; Xie, W.J.; Wei, B. [Northwestern Polytechnical University, Department of Applied Physics, Xi' an (China)

    2012-10-15

    Containerless solidification of Ni-18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition. (orig.)

  17. Containerless solidification of acoustically levitated Ni-Sn eutectic alloy

    Science.gov (United States)

    Geng, D. L.; Xie, W. J.; Wei, B.

    2012-10-01

    Containerless solidification of Ni-18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition.

  18. [Microbiological corrosion of aluminum alloys].

    Science.gov (United States)

    Smirnov, V F; Belov, D V; Sokolova, T N; Kuzina, O V; Kartashov, V R

    2008-01-01

    Biological corrosion of ADO quality aluminum and aluminum-based construction materials (alloys V65, D16, and D16T) was studied. Thirteen microscopic fungus species and six bacterial species proved to be able to attack aluminum and its alloys. It was found that biocorrosion of metals by microscopic fungi and bacteria was mediated by certain exometabolites. Experiments on biocorrosion of the materials by the microscopic fungus Alternaria alternata, the most active biodegrader, demonstrated that the micromycete attack started with the appearance of exudate with pH 8-9 on end faces of the samples. PMID:18669265

  19. The effect of cast Al-Si-Cu alloy solidification rate on alloy thermal characteristics

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2006-04-01

    Full Text Available Purpose: In the metal casting industry, an improvement of component quality depends mainly on better control over the production parameters. Thus, a thermal analysis cooling curve of the alloy is used for process control in the aluminum casting industry. In this work effect of cooling rate on the size of the grains, SDAS, size of the β precipitation and thermal characteristic results of AC AlSi9Cu cast alloy have been described. The solidification process was studied using the cooling curve and crystallization curve at solidification rate ranging from 0,16 ºCs-1 up to 1,04 ºCs-1Design/methodology/approach: The experimental alloy used in this investigation was prepared by mixing the ACAlSi5Cu commercial alloys and two master alloys AlSi49 and AlCu55. Thermal analysis tests were conducted using the UMSA Technology Platform. Cooling curve thermal analysis was performed on all samples using high sensitivity thermocouples of K type. Data were acquired by a high speed data acquisition system linked to a PC computer. Each chilled sample was sectioned horizontally where the tip of the thermocouple was located and it was prepared by standard grinding and polishing procedures. Optical microscopy was used to characterize the microstructure and intermetallic phases. Secondary Dendrite Arm Spacing measurements were carried out using an Leica Q-WinTM image analyzer.Findings: Increasing the cooling rate increases significantly the liquidus temperature, nucleation undercooling temperature, solidification range and decreases the recalescence undercooling temperature. Increasing cooling rate refines all microstructural features.Research limitations/implications: This paper presents results for one alloy - AC AlSi9Cu only, for the assessment of the Silicon Modification Level didn’t include the arrangement of a Si crystal in a matrix.Originality/value: Original value of the work is applied the artificial intelligence for the assessment of the Silicon

  20. Fluid flow solidification simulation of molten alloys

    International Nuclear Information System (INIS)

    In an effort to minimize costs and to obtain optimum designs, computer simulation of shape casting processes is more and more used as a development tool. Accurate predictions are possible by means of three dimensional fluid flow and solidification modelling. The bases of the model are the transient laminar Navier-Stokes-equations for a Newtonian fluid including the tracking of the free surface. They are describing the melt flow pattern during the mold filling sequence. Simultaneously, the temperature development in the alloy and mold is calculated using Fourier's heat transfer equation. At OEGI, a commercial software package (MAGMAsoft) with a finite difference equation solver is used for improvement of casting processes. Different examples of industrial applications will be shown. (author)

  1. Laser treatment of aluminum copper alloys: A mechanical enhancement

    International Nuclear Information System (INIS)

    Aluminum-copper alloys are commonly used as structural components for the car and aircraft industry. They combine low density, high strength, high fracture toughness and good machinability. Moreover, the strength and wear-resistance of the surface of alloys are improved by a high power laser beam. In this way the molten surface will be self-quenched by conduction of heat into the bulk. This technique ensures solidification velocities of 0.01--1 m/s. These high solidification velocities have a significant influence on the size and distribution of the morphology. This work concentrates on Al-Cu alloys, in which the Cu content ranges between 0--40 wt.%, and is aimed at describing the mechanical and microstructural properties of these alloys upon variation of the laser scan velocity in the range of 0.0125 to 0.125 m/s

  2. Topological dependence of mechanical responses of solidification microstructures in aluminum brazed joints

    Institute of Scientific and Technical Information of China (English)

    GAO Feng(高峰); QIAN Yi-yu(钱乙余); D.P.Sekulic; MA Xin(马鑫); F.Yoshida

    2003-01-01

    The main objective is to provide an evidence of spatial dependence of mechanical responses of a heterogeneous aluminum brazed joint re-solidified clad,and to confirm a sufficient sensitivity of a nano-indentation--load curve method for identifying the dependence.Topological features of a network of solidification microstructures(αphase and eutectic),formed during quench in a brazing process of aluminum alloy,influence significantly dynamic mechanical responses of resulting heterogeneous material.Nano/micro indentation depth vs load characteristics of differing phases suggest a spatially sensitive mechanical response of a re-solidified fillet in the joint zone.Hence,a spatial distribution,pattern formations and other morphological characteristics of microstructures have a direct impact on an ultimate joint integrity.Topology-induced variations of indentation-load curves was presented.A hypothesis involving microstructures'spatial distribution vs mechanical response was formulated.

  3. Functions and mechanism of modification elements in eutectic solidification of Al-Si alloys: A brief review

    Directory of Open Access Journals (Sweden)

    Zu Fangqiu

    2014-07-01

    Full Text Available Being used more and more widely in engineering, Al-Si alloys comprise about 80% of all kinds of aluminum alloys, which are the most widely utilized nonferrous alloys. Although most Al-Si alloys consist of multiple components, the eutectics in the structure accounts for 50%-90% of the sum volume of such alloys. Therefore, understanding the modification mechanism and function rules of the Al-Si eutectic solidification is the technical key in controlling the structures and properties of such casting alloys. The present paper chiefly reviews recent investigation developments and important conclusions along the lines of the functions of modification elements and their modification mechanism in the eutectic solidification of Al-Si alloys.

  4. Microstructure and properties of vacuum counter-pressure cast aluminum alloy

    OpenAIRE

    YAN Qing-song; Yu, Huan; WEI Bo-kang

    2006-01-01

    The microstructure and properties of vacuum counter-pressure cast aluminum alloy were studied. Results indicated that under the condition of vacuum counter-pressure, liquid melts fill mould cavity under the vacuum and crystallize under high pressure which have very good effect on nucleation and solidification feeding. Compared with gravity casting, the microstructure of vacuum counter-pressure cast aluminum alloy is much finer and more uniformly distributed. Mechanical properties of vacuum co...

  5. Solidification microstructure formation in HK40 and HH40 alloys

    Science.gov (United States)

    Ding, Xian-fei; Liu, Dong-fang; Guo, Pei-liang; Zheng, Yun-rong; Feng, Qiang

    2016-04-01

    The microstructure formation processes in HK40 and HH40 alloys were investigated through JmatPro calculations and quenching performed during directional solidification. The phase transition routes of HK40 and HH40 alloys were determined as L → L + γ → L + γ + M7C3 → γ + M7C3 → γ + M7C3 + M23C6→ γ + M23C6 and L → L + δ → L + δ + γ→ L + δ + γ + M23C6 δ + γ + M23C6, respectively. The solidification mode was determined to be the austenitic mode (A mode) in HK40 alloy and the ferritic-austenitic solidification mode (FA mode) in HH40 alloy. In HK40 alloy, eutectic carbides directly precipitate in a liquid and coarsen during cooling. The primary γ dendrites grow at the 60° angle to each other. On the other hand, in HH40 alloy, residual δ forms because of the incomplete transformation from δ to γ. Cr23C6 carbide is produced in solid delta ferrite δ but not directly in liquid HH40 alloy. Because of carbide formation in the solid phase and no rapid growth of the dendrite in a non-preferential direction, HH40 alloy is more resistant to cast defect formation than HK40 alloy.

  6. Investigating aluminum alloy reinforced by graphene nanoflakes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, S.J., E-mail: shaojiuyan@126.com [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Dai, S.L.; Zhang, X.Y.; Yang, C.; Hong, Q.H.; Chen, J.Z. [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Lin, Z.M. [Aviation Industry Corporation of China, Beijing 100022 (China)

    2014-08-26

    As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties' testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs.

  7. Investigating aluminum alloy reinforced by graphene nanoflakes

    International Nuclear Information System (INIS)

    As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties' testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs

  8. Hydrogen effects in aluminum alloys

    International Nuclear Information System (INIS)

    The permeability of six commercial aluminum alloys to deuterium and tritium was determined by several techniques. Surface films inhibited permeation under most conditions; however, contact with lithium deuteride during the tests minimized the surface effects. Under these conditions phi/sub D2/ = 1.9 x 10-2 exp (--22,400/RT) cc (NTP)atm/sup --1/2/ s-1cm-1. The six alloys were also tested before, during, and after exposure to high pressure hydrogen, and no hydrogen-induced effects on the tensile properties were observed

  9. Aluminum alloy impact sparkling

    Directory of Open Access Journals (Sweden)

    M. Dudyk

    2008-08-01

    Full Text Available The cast machine parts are widely used in many branches of industry. A very important issue is gaining the appropriate knowledge relating to the application of castings in places of explosion risks including but not limited to mining, chemical industry and rescue works. A possibility of explosion risks occurrence following the impact sparkling of the cast metal parts is still not solved problem in scientific research. In relation to this issue, in this article, the results of the study are presented, and relating to the tendency to impact sparkling of the aluminium alloys used in machine building. On the grounds of the results obtained, it was demonstrated that the registered impact sparkles bunches of feathers from the analyzed alloys: AlSi7Mg, (AK7; AlSi9Mg, (AK9; AlSi6Cu4, (AK64 and AlSi11, (AK11 show significant differences between each other. The quantitative analysis of the temperature distribution and nuclei surface area performed on the example of the alloy AK9 (subjected to defined period of corrosion allows for the statement that they are dangerous in conditions of explosion risk. Following this fact, designers and users of machine parts made from these materials should not use them in conditions where the explosive mixtures occur.

  10. Microbial corrosion of aluminum alloy.

    Science.gov (United States)

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors. PMID:10592801

  11. Microstructure and properties of vacuum counter-pressure cast aluminum alloy

    Directory of Open Access Journals (Sweden)

    YAN Qing-song

    2006-05-01

    Full Text Available The microstructure and properties of vacuum counter-pressure cast aluminum alloy were studied. Results indicated that under the condition of vacuum counter-pressure, liquid melts fill mould cavity under the vacuum and crystallize under high pressure which have very good effect on nucleation and solidification feeding. Compared with gravity casting, the microstructure of vacuum counter-pressure cast aluminum alloy is much finer and more uniformly distributed. Mechanical properties of vacuum counter-pressure cast aluminum alloy are improved significantly.

  12. Pore structure and mechanical properties of directionally solidified porous aluminum alloys

    Directory of Open Access Journals (Sweden)

    Komissarchuk Olga

    2014-01-01

    Full Text Available Porous aluminum alloys produced by the metal-gas eutectic method or GASAR process need to be performed under a certain pressure of hydrogen, and to carry over melt to a tailor-made apparatus that ensures directional solidification. Hydrogen is driven out of the melt, and then the quasi-cylindrical pores normal to the solidification front are usually formed. In the research, the effects of processing parameters (saturation pressure, solidification pressure, temperature, and holding time on the pore structure and porosity of porous aluminum alloys were analyzed. The mechanical properties of Al-Mg alloys were studied by the compressive tests, and the advantages of the porous structure were indicated. By using the GASAR method, pure aluminum, Al-3wt.%Mg, Al-6wt.%Mg and Al-35wt.%Mg alloys with oriented pores have been successfully produced under processing conditions of varying gas pressure, and the relationship between the final pore structure and the solidification pressure, as well as the influences of Mg quantity on the pore size, porosity and mechanical properties of Al-Mg alloy were investigated. The results show that a higher pressure of solidification tends to yield smaller pores in aluminum and its alloys. In the case of Al-Mg alloys, it was proved that with the increasing of Mg amount, the mechanical properties of the alloys sharply deteriorate. However, since Al-3%Mg and Al-6wt.%Mg alloys are ductile metals, their porous samples have greater compressive strength than that of the dense samples due to the existence of pores. It gives the opportunity to use them in industry at the same conditions as dense alloys with savings in weight and material consumption.

  13. Evolution of eutectic spacing during unidirectional solidification of Al-Ni alloys

    Directory of Open Access Journals (Sweden)

    Igor Jefferson Cabral Araujo

    2011-01-01

    Full Text Available Hypoeutectic Al-Ni alloys show a ductile phase α distributed with a β phase Al3Ni fragile where β serves as reinforcement of the structure of the material. The eutectic composition alloys obey the relationship: λ2.v = C, where λ is the eutectic spacing, v is a tip growth rate and C is a constant. The aim of this study is to establish correlations between λ and v for hypoeutectic Al-1%, 3% and 5% Ni alloys. Unsteady-state upward directional solidification experiments were performed, as well as metallography, dissolution of the aluminum matrix and scanning electron microscopy (SEM. The interphase spacing of the three Al-Ni alloys decreased with increasing tip growth rate, with a predominance of a rod-like morphology on intermetallic. It was observed that parameters such as tip growth rate, cooling rate and temperature gradient decreases as the solidification front advances. It was further observed that a single experimental law λ = 1.2 v-0, 5 illustrates the evolution of the interphase spacing for any examined alloy.

  14. Linear Stability of Binary Alloy Solidification for Unsteady Growth Rates

    Science.gov (United States)

    Mazuruk, K.; Volz, M. P.

    2010-01-01

    An extension of the Mullins and Sekerka (MS) linear stability analysis to the unsteady growth rate case is considered for dilute binary alloys. In particular, the stability of the planar interface during the initial solidification transient is studied in detail numerically. The rapid solidification case, when the system is traversing through the unstable region defined by the MS criterion, has also been treated. It has been observed that the onset of instability is quite accurately defined by the "quasi-stationary MS criterion", when the growth rate and other process parameters are taken as constants at a particular time of the growth process. A singular behavior of the governing equations for the perturbed quantities at the constitutional supercooling demarcation line has been observed. However, when the solidification process, during its transient, crosses this demarcation line, a planar interface is stable according to the linear analysis performed.

  15. Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system

    Science.gov (United States)

    Fujinaga, Shigeki; Ohashi, Ryoji; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    In high power YAG laser welding of steels, a rectangularly modulated beam with high peak power is usually used to get deep penetration. On the other hand, many spatters and solidification cracks are generated when some aluminum alloys are welded with a rectangularly modulated beam because of its high heat conductivity, high reflectivity, low surface tension, large contraction, wide solidification temperature range, etc. Therefore, a properly modulated beam or a continuous beam is usually used in aluminum alloy welding, although the penetration depth is shallow. In this research, sinusoidal wave or rectangularly modulated wave of YAG laser combined with TIG arc was tried to improve the weldability of A6061 aluminum alloy. As a result, when TIG arc was superimposed behind the YAG laser beam, deeply penetrated weld beads with good surface appearances were produced without spatter losses and cracks.

  16. Low-aluminum content iron-aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J. [and others

    1995-06-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10 and iron = 83.71. The ignots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot-worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  17. Effects of High Magnetic Field on Solidification and Corrosion Behaviors of Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The solidification behaviors of AZ61 magnesium alloy under a high magnetic field were studied. The corrosion property of AZ61 alloy was investigated in a solution of 3.5 mol/L NaCl by measuring electrochemical polarization. The results show that the high magnetic field can refine microstructure and benefit aluminum transfer.The crystal of α-Mg is induced to orient with their c-axis parallel to the magnetic field. The corrosion studies indicate that different crystal plane of magnesium has different corrosion property. The passivating films on the a- and b-planes have higher corrosion resistance than that on the c-plane. Aligned structure affects the corrosion property of AZ61 magnesium alloy.

  18. Advanced powder metallurgy aluminum alloys and composites

    Science.gov (United States)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  19. Materials data handbook, aluminum alloy 6061

    Science.gov (United States)

    Sessler, J.; Weiss, V.

    1969-01-01

    Comprehensive compilation of technical data on aluminum alloy 6061 is presented in handbook form. The text includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent information required for the design and fabrication of components and equipment utilizing this alloy.

  20. Vertical solidification of dendritic binary alloys

    Science.gov (United States)

    Heinrich, J. C.; Felicelli, S.; Poirier, D. R.

    1991-01-01

    Three numerical techniques are employed to analyze the influence of thermosolutal convection on defect formation in directionally solidified (DS) alloys. The finite-element models are based on the Boussinesq approximation and include the plane-front model and two plane-front models incorporating special dendritic regions. In the second model the dendritic region has a time-independent volume fraction of liquid, and in the last model the dendritic region evolves as local conditions dictate. The finite-element models permit the description of nonlinear thermosolutal convection by treating the dendritic regions as porous media with variable porosities. The models are applied to lead-tin alloys including DS alloys, and severe segregation phenomena such as freckles and channels are found to develop in the DS alloys. The present calculations and the permeability functions selected are shown to predict behavior in the dendritic regions that qualitatively matches that observed experimentally.

  1. 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.

  2. Solidification and precipitation in aluminium-zirconium alloys. Pt. 1

    International Nuclear Information System (INIS)

    The cast structure and the precipitating primary phases were investigated in Al-Zr alloys on the basis of high-purity Aluminium with 0.1 to 1.2 wt.% Zr after fast solidification in a watercooled mold. With higher Zr-saturation of the melt the tetragonal ZrAl3-equilibrium phase appears, which is already known from slowly cooled samples. In alloys with lower Zr-supersaturation with respect to the raised Zr-solubility of about 0.6 wt.% due to the fast solidification there appears solely or additionally the new metastable cubic ZrAl3-phase as the primary precipitation. The particles show cubic or fourfold symmetric star form and have nearly the same lattice parameters as Aluminium. By coherent epitaxi of the Al-lattice they act as prefered nuclei for the solidification of the α-phase. Consequently an intensive grain refining takes place in a critical concentration range depending on temperature of pouring and cooling rate. (orig.)

  3. Rapid solidification of undercooled Al-Cu-Si eutectic alloys

    Institute of Scientific and Technical Information of China (English)

    RUAN Ying; WEI BingBo

    2009-01-01

    Under the conventional solidification condition,a liquid aluminium alloy can be hardly undercooled because of oxidation.In this work,rapid solidification of an undercooled liquid Al,80.4Cu,13.6Si,6 ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating.The re-lationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt.The maximum undercooling is 147 K (0.18 TE).The undercooled ternary eutectic is composed of α(Al) solid solution,(Si) semiconductor and β(CuAl,2) intermetallic compound.In the (Al+Si+θ) ternary eutectic,(Si) faceted phase grows independently,while (Al) and θ non-faceted phases grow coopera-tively in the lamellar mode.When undercooling is small,only (Al) solid solution forms as the leading phase.Once undercooling exceeds 73 K,(Si) phase nucleates firstly and grows as the primary phase.The alloy microstructure consists of primary (Al) dendrite,(Al+9) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling,while at large undercooling primary (Si) block,(Al+θ) pseudo-binary eutectic and (Al+Si+θ) ternary eutectic coexist.As undercooling increases,the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases.

  4. Microstructure analysis of Al-Si-Cu alloys prepared by gradient solidification technique

    Science.gov (United States)

    Borkar, Hemant; Seifeddine, Salem; Jarfors, Anders E. W.

    2015-03-01

    Al-Si-Cu alloys were cast with the unique gradient solidification technique to produce alloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of 9 and 27 μm covering the microstructural fineness of common die cast components. The microstructure was studied with optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, has a more homogeneous microstructure with well distributed network of eutectic and intermetallic phases. The results indicate the presence of Al-Fe-Si phases, Al-Cu phases and eutectic Si particles but their type, distribution and amount varies in the two alloys with different SDAS. EBSD analysis was also performed to study the crystallographic orientation relationships in the microstructure. One of the major highlights of this study is the understanding of the eutectic formation mechanism achieved by studying the orientation relationships of the aluminum in the eutectic to the surrounding primary aluminum dendrites.

  5. Two-dimensional cellular automaton model for simulating structural evolution of binary alloys during solidification

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; ZHANG Cai-bei

    2006-01-01

    Two-dimensional cellular automaton(CA) simulations of phase transformations of binary alloys during solidification were reported. The modelling incorporates local concentration and heat changes into a nucleation or growth function, which is utilized by the automaton in a probabilistic fashion. These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification. The simulated results show that the final morphology during solidification is related with the cooling conditions. The established model can be used to evaluate the phase transformation of binary alloys during solidification.

  6. Computer modelling of solidification of pure metals and alloys

    CERN Document Server

    Barkhudarov, M R

    1995-01-01

    differencing advection algorithm used in the simulations, the Leith's method is incorporated into the public domain two-dimensional SOLA code. It is shown that the resulting scheme is unconditionally stable despite being explicit. Two numerical models have been developed to describe the volumetric changes during solidification in pure metals and alloys and to predict shrinkage defects in the castings of general three-dimensional configuration. The first model is based on the full system of the Continuity, Navier-Stokes and Enthalpy Equations. Volumetric changes are described by introducing a source term in the Continuity Equation which is a function of the rate of local phase transformation. The model is capable of simulating both volumetric shrinkage and expansion. The second simplified shrinkage model involves the solution of only the Enthalpy Equation. Simplifying assumptions that the feeding flow is governed only by gravity and solidification rate and that phase transformation proceeds only from liquid to...

  7. Phase field simulation of equiaxed solidification in technical alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boettger, B. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany); Eiken, J. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany); Steinbach, I. [RWTH-Aachen, Access e.V., Intzestrasse 5, 52072 Aachen (Germany)]. E-mail: I.Steinbach@access.rwth-aachen.de

    2006-06-15

    It is shown how the phase field method can be applied to simulate the equiaxed solidification of commercial alloys in technical processes. A multicomponent multiphase field model is coupled to thermodynamic databases. To handle the complex phase diagrams a local quasi-binary extrapolation is applied. Nucleation is treated by statistically distributed seed particles, taking into account the shielding of nucleation sites by recalescence, solute diffusion and growth of solid phases. To reduce computation time it is discussed how three-dimensional phenomena can be approximated by two-dimensional simulations, and the model for latent heat release is adjusted accordingly. As examples, simulations are presented of the commercial Mg-Al-Zn alloy AZ31, a hypereutectic Al-Si-Cu-Mg-Ni piston alloy and AlCu{sub 4}Si{sub 17}Mg.

  8. Materials data handbook: Aluminum alloy 2219

    Science.gov (United States)

    Muraca, R. F.; Whittick, J. S.

    1972-01-01

    A summary of the materials property information for aluminum 2219 alloy is presented. The scope of the information includes physical and mechanical properties at cryogenic, ambient, and elevated temperatures. Information on material procurement, metallurgy of the alloy, corrosion, environmental effects, fabrication, and joining techniques is developed.

  9. Friction Stir Welding of Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    FU Zhi-hong; HE Di-qiu; WANG Hong

    2004-01-01

    Friction stir welding(FSW), a new solid-state welding technology invited in the early 1990s,enables us weld aluminum alloys and titanium alloys etc. The processing of FSW, the microstructure in FSW alloysand the factors influencing weld quality are introduced. The complex factors affecting the properties are researched.

  10. High speed twin roll caste for aluminum alloy thin strip

    Directory of Open Access Journals (Sweden)

    T. Haga

    2007-09-01

    Full Text Available Purpose: In the present study, effectiveness of a high-speed twin roll caster for recycling aluminum alloy was investigated.Design/methodology/approach: The effects of the high-speed twin roll caster on alleviating the deterioration of mechanical properties by impurities were investigated. Properties of the cast strip were investigated by metalography, a tension test, and a bending test.Findings: A vertical type twin roll caster for strip casting of aluminum alloys was devised. The strip, which was thinner than 3 mm, could be cast at speeds higher than 60 m/min. Features of the twin roll casters are as below. Copper rolls were used and lubricant was not used in order to increase the casting speed. A casting nozzle was used to set the solidification length precisely. Heat transfer between melt and the roll was improved by hydrostatic pressure of the melt. Separating force was very small in order to prevent sticking of the strip to the roll. Low superheat casting was carried out in order to improve microstructure of the strip. In the present study, effectiveness of a high-speed and high-cooling rate twin roll caster of the present study for recycling aluminum alloy was investigated. Fe was added as impurity to 6063 and A356. The roll caster of the present study was useful to decrease the influence of impurity of Fe.Research limitations/implications: A high-speed twin roll caster of vertical type was designed and assembled to cast aluminum alloy thin strip.Originality/value: The results demonstrate that the high-speed twin roll caster can improve the deterioration by impurities.

  11. Minimizing Segregation during the Controlled Directional Solidification of Dendric Alloys

    Science.gov (United States)

    Grugel, Richard N.; Fedoseyev, Alex; Kim, Shin-Woo

    2003-01-01

    Gravity-driven convection induced in the liquid by density gradients of temperature or composition disrupts uniform dendritic growth during controlled directional solidification and promotes severe macrosegregation. The solute-rich region about the dendrite tip appears to play a pivotal role in channel initiation. Allen and Hunt referred to this region as an "initial transient" or dynamic region constituting steep concentration gradients. Experimental investigation also point to the role the tip region plays in developing microstructure. Hellawell and co-workers showed that flow-through dendritic channels could be effectively disrupted, and segregation minimized, during the gradient freezing of bulk castings by rotating the melt through a slight angle with respect to Earth's gravity vector. Adapting this principle to controlled directional solidification, it has been shown" that segregation in dendritic alloys can be minimized, and properties improved, by processing the sample near horizontal in conjunction with a slow axial rotation of the crucible. It is postulated that the observed microstructural uniformity arises by maintaining the developing solute field about the dendrite tip. Solute rejected during vertical directional solidification will rise or sink parallel to the primary dendrite arms during axial rotation setting the stage for accumulation, instabilities, and segregation. In contrast, during horizontal growth, the rejected solute will sink or rise perpendicular to the primary dendrite. Now, in the presence of a slight axial rotation, solute that was initially sinking (or rising) will find itself above (or below) its parent dendrite, i.e., still about the tip region. The following is intended to experimentally demonstrate the viability of this concept in coordination with a model that gives predictive insight regarding solute distribution about growing dendrites. Alloys based on the lead-tin eutectic system were used in this study. The system is well

  12. Investigation of solidification dynamics of Zr-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kobold, Raphael; Herlach, Dieter [Institut fuer Materialphysik im Weltraum, Deutsches Zentrum fuer Luft- und Raumfahrt, 51170 Koeln (Germany); Ruhr-Universitaet Bochum, 44780 Bochum (Germany)

    2013-07-01

    In contrast to experiments with most undercooled binary alloys the velocity of dendritic growth of a Cu50Zr50 alloy does not increase monotonically with undercooling but passes through a maximum and then decreases. To study this behaviour we investigate Zr-based alloys such as CuZr, NiZr and NiZrAl with Zirconium concentrations ranging from 36 to 64 at.% including eutectic and intermetallic phases. We use electrostatic levitation technique to melt and undercool samples with a diameter of 2-3 mm under ultra-high-vacuum conditions. Containerless processing is an effective tool for undercooling metallic melts far below their equilibrium melting temperatures since heterogeneous nucleation on container walls is completely avoided. During crystallisation of the undercooled melt the heat of crystallisation is released. The rapid increase of the temperature at the solid-liquid interface makes the solidification front visible. The velocities of the solidification front are recorded by using a high-speed camera with a maximum rate of 50.000 frames per second and are analyzed with a software for optical ray tracing. Furthermore, we try to model the growth velocity vs. the undercooling temperature and perform sample EBSD analysis with a scanning electron microscope.

  13. Numerical modelling of the binary alloys solidification with solutal undercooling

    Directory of Open Access Journals (Sweden)

    T. Skrzypczak

    2008-03-01

    Full Text Available In thc papcr descrip~ion of mathcmn~icaI and numerical modcl of binay alloy sot idification is prcscntcd. Mctal alloy consisting of maincomponent and solulc is introduced. Moving, sharp solidification rmnt is assumcd. Conaitulional undcrcooling phcnomcnon is tnkcn intoconsidcralion. As a solidifica~ionf ront advances, solutc is rcdistributcd at thc intcrfacc. Commonly, solutc is rejccted into Itlc liquid. whcrcit accumuIatcs into solittc boundary laycr. Depending on thc tcmpcrature gradient, such tiquid may be undcrcoolcd hclow its mclting point,cvcn though it is hot~crth an liquid at thc Front. This phcnomcnon is orten callcd constitutional or soIr~talu ndcrcool ing, to cmphasizc that itariscs from variations in solutal distribution or I iquid. An important conscqucncc of this accurnulntion of saIutc is that it can cause thc frontto brcak down into cclls or dendri~csT. his occurs bccausc thcrc is a liquid ahcad of thc front with lowcr solutc contcnt, and hcncc a highcrme1 ting tcmpcraturcs than liquid at thc front. In rhc papcr locarion and shapc of wndcrcoolcd rcgion dcpcnding on solidification pararnctcrsis discussed. Nurncrical mcthod basing on Fini tc Elelncnt Mctbod (FEM allowi~lgp rcdiction of breakdown of inoving planar front duringsolidification or binary alloy is proposed.

  14. Modelling of the rheological behavior of metallic alloys during solidification

    International Nuclear Information System (INIS)

    During alloy processing technologies such as DC casting, mould casting or laser welding, thermally induced deformations occur arising from both solidification shrinkage and thermal contraction of the solid skeleton. Although relatively small, these thermal strains can lead to severe casting defects such as macrosegregation, porosity and hot tears. In order to understand the formation of these defects, the rheological behavior of the alloy has to be modeled during solidification and particularly at the end of the process when the volume fraction of the liquid becomes very small. The approach that has been developed is to consider the mushy zone as a compressible porous medium saturated with liquid. This means that the solid skeleton is not considered as a Von Mises material, but is a pressure dependent medium. The effect of the liquid pressure on the solid skeleton is taken into account together with the very different mechanical response of the material between tensile and compressive stress states. Moreover, the partial cohesion of the mushy zone is introduced in the constitutive model as an internal variable to account for the apparent strain hardening that occurs during deformation at small strains. This approach has been validated for pure shear in a recent study. The present work extends the investigation to the entire stress space. The necessary simplifications that might be needed for the experimental identification are discussed. Various types of experiments have been designed for the identification of the model in the case of Al-alloys including tensile and shear experiments together with drained compression. Tests have been carried out both at constant temperature or during the course of solidification to investigate the effect of the strain rate (in the low strain rate range) and solid fraction. Analysis of the results is in progress to identify the various parameters of the model. Refs. 1 (author)

  15. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  16. Applications of the directional solidification in magnetic shape memory alloys

    Science.gov (United States)

    Huang, Y. J.; Liu, J.; Hu, Q. D.; Liu, Q. H.; Karaman, I.; Li, J. G.

    2016-03-01

    A zone melting liquid metal cooling (ZMLMC) method of directional solidification was applied to prepare highly-oriented Ni52Fe17Ga27Co4 magnetic shape memory alloys. At high temperature gradient and low growth velocity, the well-developed preferred orientation for coarse columnar crystals was obtained. Such a structure leads to a large complete pseudoelastic recovery of 5% at 348 K. Moreover, the pseudoelastic behaviours and the kinetics of the martensitic transformation (MT) are significantly affected by the intersection angle between the loading direction and the grain boundaries.

  17. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T(e and N(e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T(e and N(e for the aluminum in aluminum alloys using an optical fiber probe.

  18. Superior metallic alloys through rapid solidification processing (RSP) by design

    Energy Technology Data Exchange (ETDEWEB)

    Flinn, J.E. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States)

    1995-05-01

    Rapid solidification processing using powder atomization methods and the control of minor elements such as oxygen, nitrogen, and carbon can provide metallic alloys with superior properties and performance compared to conventionally processing alloys. Previous studies on nickel- and iron-base superalloys have provided the baseline information to properly couple RSP with alloy composition, and, therefore, enable alloys to be designed for performance improvements. The RSP approach produces powders, which need to be consolidated into suitable monolithic forms. This normally involves canning, consolidation, and decanning of the powders. Canning/decanning is expensive and raises the fabrication cost significantly above that of conventional, ingot metallurgy production methods. The cost differential can be offset by the superior performance of the RSP metallic alloys. However, without the performance database, it is difficult to convince potential users to adopt the RSP approach. Spray casting of the atomized molten droplets into suitable preforms for subsequent fabrication can be cost competitive with conventional processing. If the fine and stable microstructural features observed for the RSP approach are preserved during spray casing, a cost competitive product can be obtained that has superior properties and performance that cannot be obtained by conventional methods.

  19. Numerical simulation of freckle formation in directional solidification of binary alloys

    Science.gov (United States)

    Felicelli, Sergio D.; Heinrich, Juan C.; Poirier, David R.

    1992-01-01

    A mathematical model of solidification is presented which simulates the formation of segregation models known as 'freckles' during directional solidification of binary alloys. The growth of the two-phase or dendritic zone is calculated by solving the coupled equations of momentum, energy, and solute transport, as well as maintaining the thermodynamic constraints dictated by the phase diagram of the alloy. Calculations for lead-tin alloys show that the thermosolutal convection in the dendritic zone during solidification can produce heavily localized inhomogeneities in the composition of the final alloy.

  20. Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification

    Energy Technology Data Exchange (ETDEWEB)

    Huang, C.; Kou, S.

    2000-05-01

    Aluminum Alloy 2219 was welded by gas metal arc welding and the microstructure was examined in the partially melted zone (PMZ), which is a narrow region immediately outside the fusion zone. Extensive liquation was observed at three different locations: at large {theta} (Al{sub 2}Cu) particles, along grain boundaries (GBs) and at numerous isolated points within grains. Liquation was initiated at the eutectic temperature T{sub E}, by the eutectic reaction {alpha} + {theta} {r_arrow} L{sub E} and intensified by further melting, above T{sub E}, of the {alpha} matrix surrounding the eutectic liquid (L{sub E}). The microstructure of the liquated-and-solidified GB material is intriguing. First, the material consisted of a new GB of mostly thin, divorced eutectic and a eutectic-free strip of {alpha} immediately next to it. Second, within an individual grain, the strip was along the top and the side facing the weld. Third, with respect to the weld, the strip was always behind the new GB. These three characteristics point to an important phenomenon, that is, solidification of the liquated GB is directional - upward and toward the weld, as a result of the temperature gradients across the PMZ. A thin, brittle eutectic GB and a soft ductile {alpha} strip side by side are expected to be much weaker than a normal GB before welding.

  1. SOLIDIFICATION CHARACTERISTIC OF TITANIUM CARBIDE PARTICULATE REINFORCED ALUMINIUM ALLOY MATRIX COMPOSITES

    Directory of Open Access Journals (Sweden)

    N. FATCHURROHMAN

    2012-04-01

    Full Text Available In this research solidification characteristic of metal matrix composites consisted of titanium carbide particulate reinforced aluminium-11.8% silicon alloy matrix is performed. Vortex mixing and permanent casting method are used as the manufacturing method to produce the specimens. Temperature measurements during the casting process are captured and solidification graphs are plotted to represent the solidification characteristic. The results show, as volume fraction of particulate reinforcement is increased, solidification time is faster. Particulate reinforcement promotes rapid solidification which will support finer grain size of the casting specimen. Hardness test is performed and confirmed that hardness number increased as more particulate are added to the system.

  2. The Solidification Velocity of Undercooled Nickel and Titanium Alloys with Dilute Solute

    Science.gov (United States)

    Algoso, Paul R.; Altgilbers, A. S.; Hofmeister, William H.; Bayuzick, Robert J.

    2003-01-01

    The study of solidification velocity is important for two reasons. First, understanding the manner in which the degree of undercooling of the liquid and solidification velocity affect the microstructure of the solid is fundamental. Second, there is disagreement between theoretical predictions of the relationship between undercooling and solidification velocity and experimental results. Thus, the objective of this research is to accurately and systematically quantify the solidification velocity as a function of undercooling for dilute nickel-and titanium-based alloys. The alloys chosen for study cover a wide range of equilibrium partition coefficients, and the results are compared to current theory.

  3. Solidification Processing of Te–Sb–Pb Alloys For Thermoelectric Applications

    OpenAIRE

    Ikeda, Teruyuki; Azizgolshani, Hesham; Haile, Sossina; Snyder, G. Jeffrey; Ravi, Vilupanur

    2005-01-01

    A solidification processing approach to the refinement of lead-tellurium-antimony alloy microstructure is described. Liquid alloys with eutectic, hyper-eutectic and hypo-eutectic compositions (relative to lead) were cooled to the solid state in three distinct ways, i.e. by water quenching, air cooling and furnace cooling. The structures of the alloys resulting from the three different solidification paths were examined using electron microscopy and the micrographs were quantified. Classical s...

  4. Computer modelling of solidification of pure metals and alloys

    International Nuclear Information System (INIS)

    Two numerical models have been developed to describe the volumetric changes during solidification in pure metals and alloys and to predict shrinkage defects in the castings of general three-dimensional configuration. The first model is based on the full system of the Continuity, Navier-Stokes and Enthalpy Equations. Volumetric changes are described by introducing a source term in the Continuity Equation which is a function of the rate of local phase transformation. The model is capable of simulating both volumetric shrinkage and expansion. The second simplified shrinkage model involves the solution of only the Enthalpy Equation. Simplifying assumptions that the feeding flow is governed only by gravity and solidification rate and that phase transformation proceeds only from liquid to solid allowed the fluid flow equations to be excluded from consideration. The numerical implementation of both models is based on an existing proprietary general purpose CFD code, FLOW-3D, which already contains a numerical algorithm for incompressible fluid flow with heat transfer and phase transformation. An important part of the code is the Volume Of Fluid (VOF) algorithm for tracking multiple free surfaces. The VOF function is employed in both shrinkage models to describe shrinkage cavity formation. Several modifications to FLOW-3D have been made to improve the accuracy and efficiency of the metal/mould heat transfer and solidification algorithms. As part of the development of the upwind differencing advection algorithm used in the simulations, the Leith's method is incorporated into the public domain two-dimensional SOLA code. It is shown that the resulting scheme is unconditionally stable despite being explicit. (author)

  5. [The corrosion resistance of aluminum and aluminum-based alloys studied in artificial model media].

    Science.gov (United States)

    Zhakhangirov, A Zh; Doĭnikov, A I; Aboev, V G; Iankovskaia, T A; Karamnova, V S; Sharipov, S M

    1991-01-01

    Samples of aluminum and its alloys, designed for orthodontic employment, were exposed to 4 media simulating the properties of biologic media. The corrosion resistance of the tested alloys was assessed from the degree of aluminum migration to simulation media solutions, which was measured by the neutron activation technique. Aluminum alloy with magnesium and titanium has shown the best corrosion resistance. PMID:1799002

  6. Rapid Solidification of AB{sub 5} Hydrogen Storage Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gulbrandsen-Dahl, Sverre

    2002-01-01

    This doctoral thesis is concerned with rapid solidification of AB{sub 5} materials suitable for electrochemical hydrogen storage. The primary objective of the work has been to characterise the microstructure and crystal structure of the produced AB{sub 5} materials as a function of the process parameters, e.g. the cooling rate during rapid solidification, the determination of which has been paid special attention to. The thesis is divided into 6 parts, of which Part I is a literature review, starting with a short presentation of energy storage alternatives. Then a general review of metal hydrides and their utilisation as energy carriers is presented. This part also includes more detailed descriptions of the crystal structure, the chemical composition and the hydrogen storage properties of AB{sub 5} materials. Furthermore, a description of the chill-block melt spinning process and the gas atomisation process is given. In Part II of the thesis a digital photo calorimetric technique has been developed and applied for obtaining in situ temperature measurements during chill-block melt spinning of a Mm(NiCoMnA1){sub 5} hydride forming alloy (Mm = Mischmetal of rare earths). Compared with conventional colour transmission temperature measurements, this technique offers a special advantage in terms of a high temperature resolutional and positional accuracy, which under the prevailing experimental conditions were found to be {+-}29 K and {+-} 0.1 mm, respectively. Moreover, it is shown that the cooling rate in solid state is approximately 2.5 times higher than that observed during solidification, indicating that the solid ribbon stayed in intimate contact with the wheel surface down to very low metal temperatures before the bond was broken. During this contact period the cooling regime shifted from near ideal in the melt puddle to near Newtonian towards the end, when the heat transfer from the solid ribbon to the wheel became the rate controlling step. In Part III of the

  7. Solidification mechanism of highly undercooled metal alloys. [tin-lead and nickel-tin alloys

    Science.gov (United States)

    Shiohara, Y.; Chu, M. G.; Macisaac, D. G.; Flemings, M. C.

    1982-01-01

    Experiments were conducted on metal droplet undercooling, using Sn-25wt%Pb and Ni-34wt%Sn alloys. To achieve the high degree of undercooling, emulsification treatments were employed. Results show the fraction of supersaturated primary phase is a function of the amount of undercooling, as is the fineness of the structures. The solidification behavior of the tin-lead droplets during recalescence was analyzed using three different hypotheses; (1) solid forming throughout recalescence is of the maximum thermodynamically stable composition; (2) partitionless solidification below the T sub o temperature, and solid forming thereafter is of the maximum thermodynamically stable composition; and (3) partitionless solidification below the T sub o temperature with solid forming thereafter that is of the maximum thermodynamically metastable composition that is possible. The T sub o temperature is calculated from the equal molar free energies of the liquid solid using the regular solution approximation.

  8. First analysis of a numerical benchmark for 2D columnar solidification of binary alloys

    OpenAIRE

    Arquis, Eric; Bellet, Michel; Combeau, Hervé; Fautrelle, Yves; Gobin, Dominique; Budenkova, Olga; Dussoubs, Bernard; Duterrail, Yves; Kumar, Arvind; Mosbah, Salem; Rady, Mohamed; Gandin, Charles-André; Goyeau, Benoit; Zaloznik, Miha

    2011-01-01

    During the solidification of metal alloys, chemical heterogeneities at the product scale (macrosegregation) develop. Numerical simulation tools are beginning to appear in the industry, however their predictive capabilities are still limited. We present a numerical benchmark exercise treating the performance of models in the prediction of macrosegregation. In a first stage we defined a "minimal" (i.e. maximally simplified) solidification model, describing the coupling of the solidification of ...

  9. Probability Distribution Function Evolution for Binary Alloy Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Steinzig, M.L.; Harlow, F.H.

    1999-02-26

    The thermally controlled solidification of a binary alloy, nucleated at isolated sites, is described by the evolution of a probability distribution function, whose variables include grain size and distance to nearest neighbor, together with descriptors of shape, orientation, and such material properties as orientation of nonisotropic elastic modulus and coefficient of thermal expansion. The relevant Liouville equation is described and coupled with global equations for energy and solute transport. Applications are discussed for problems concerning nucleation and impingement and the consequences for final size and size distribution. The goal of this analysis is to characterize the grain structure of the solidified casting and to enable the description of its probable response to thermal treatment, machining, and the imposition of mechanical insults.

  10. Corrosion of aluminum alloys as a function of alloy composition

    International Nuclear Information System (INIS)

    A study was initiated which included nineteen aluminum alloys. Tests were conducted in high purity water at 3600C and flow tests (approx. 20 ft/sec) in reactor process water at 1300C (TF-18 loop tests). High-silicon alloys and AlSi failed completely in the 3600C tests. However, coupling of AlSi to 8001 aluminum suppressed the failure. The alloy compositions containing iron and nickel survived tht 3600C autoclave exposures. Corrosion rates varied widely as a function of alloy composition, but in directions which were predictable from previous high-temperature autoclave experience. In the TF-18 loop flow tests, corrosion penetrations were similar on all of the alloys and on high-purity aluminum after 105 days. However, certain alloys established relatively low linear corrosion rates: Al-0.9 Ni-0.5 Fe-0.1 Zr, Al-1.0 Ni-0.15 Fe-11.5 Si-0.8 Mg, Al-1.2 Ni-1.8 Fe, and Al-7.0 Ni-4.8 Fe. Electrical polarity measurements between AlSi and 8001 alloys in reactor process water at temperatures up to 1500C indicated that AlSi was anodic to 8001 in the static autoclave system above approx. 500C

  11. Effect of chemical composition and cooling conditions on solidification hot cracking of Ni-based alloys

    International Nuclear Information System (INIS)

    Ni-based alloys 690 present solidification hot cracks during welding of vapour generators. Hot cracks are qualitatively known to be due to the formation of inter-dendritic liquid films and of secondary phases down to low temperatures. This study aims at establishing the link between thermodynamics, solidification and hot cracking. Experimental solidification paths of high purity alloys (with varying Nb and Si contents) are obtained from quenching during directional solidification and TIG-welding experiments. They are compared to Thermo-Calc computations, assuming no diffusion in the solid. From directional solidification samples, good agreement between computed and experimental solidification paths is shown in the quenched liquid. Secondary arms of dendrites are affected by solid state diffusion of Nb. Combined effect of diffusion and solute build-up in the liquid phase modifies micro-segregation in the solid region. Solidification paths from welding specimens are similar to those of the solid region of quenched samples. Nb solid state diffusion is negligible but undercooling compensates the effect of solid state diffusion in directional solidification. Evolution of liquid fraction at the end of the solidification is in accordance with the hot cracking classification of the alloys. Nb favours formation of inter-dendritic liquid films and eutectic-like phases down to low temperature. (author)

  12. Impact of External Pressure on the Heat Transfer Coefficient during Solidification of Al-A356 Alloy

    DEFF Research Database (Denmark)

    Jabbari, Masoud; Ilkhchy, A.Fardi; Moumani, E.

    In this paper the interfacial heat transfer coefficient (IHTC) is correlated to applied external pressure, in which IHTC at the interface between A356 aluminum alloy and metallic mold during the solidification of the casting under different pressures were obtained using the Inverse Heat Conduction...... Problem (IHCP) method. The method covers the expedient of comparing theoretical and experimental thermal histories. Temperature profiles obtained from thermocouples were used in a finite difference heat flow program to estimate the transient heat transfer coefficients. The new simple formula was presented...

  13. Mathematical model and numerical simulation of aluminum casting and solidification in magnetic fields with allowance for free surface dynamics

    Science.gov (United States)

    Minakov, A. V.; Pervukhin, M. V.; Platonov, D. V.; Khatsayuk, M. Yu.

    2015-12-01

    A complex mathematical model of aluminum casting and solidification in a variable electromagnetic field is constructed. The model is based on the solution of magnetohydrodynamic equations and the VOF method. Test results are presented for the model and the numerical algorithm proposed. The numerical results are compared with experimental data and computations of other authors and are found to be in good agreement. The model is used to simulate aluminum solidification under an electromagnetic field. The physical processes influencing ingot formation are analyzed.

  14. Casting Characteristics of Aluminum Die Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  15. Galvanic aspects of aluminum sacrificial anode alloys in seawater.

    OpenAIRE

    Cummings, Jon Richard

    2012-01-01

    Galvanic aspects of aluminum sacrificial anode alloys in artificial seawater were investigated. Specifically, two mercury-bearing alloys and one tin-bearing alloy were studied. The polarization behavior of the aluminum sacrificial anode alloys coupled to HY-80 steel is discussed. Current versus time curves were obtained for aluminum/steel galvanic couples immersed in artificial seawater for specific intervals. Scanning elecron microscopy was used to characterize the anode dissolution patt...

  16. Solidification of binary alloy in a finned enclosure from the bottom

    Energy Technology Data Exchange (ETDEWEB)

    Tan, F.L. [Nanyang Technological University, School of Mechanical and Aerospace Engineering, Singapore (Singapore)

    2009-01-15

    This paper presents experimental findings on the phenomenon of solidification of a binary alloy in a finned enclosure using aqueous ammonium chloride solution. Solidification experiments are carried out over a wide range of initial composition of binary alloy solution from hypoeutectic to hypereutectic concentration ranging from 8, 16 and 24% of ammonium chloride are discussed. An interesting ''snowing'' phenomenon is observed for the hypereutectic concentration in a finned enclosure. (orig.)

  17. Numerical simulation on directional solidification of Al-Ni-Co alloy based on FEM

    Directory of Open Access Journals (Sweden)

    Yang Zhili

    2010-02-01

    Full Text Available The ratio, of the temperature gradient at the solidification front to the solidification rate of solid-liquid interface, plays a large part in columnar grain growth. The transient temperature fields of directional solidification of Al-Ni-Co alloy were studied by employing a finite element method. The temperature gradient at the solidification front and the solidification rate were analyzed for molten steels pouring at different temperatures. The results show that with different initial pouring temperatures, the individual ratio of the temperature gradient at solidification front to the solidification rate soars up in the initial stage of solidification, then varies within 2,000-6,000 ℃·s·cm-2, and finally goes down rapidly and even tend to be closed to each other when the solidification thickness reaches 5-6 cm. The simulation result is consistent with the practical production which can provide an available reference for process optimization of directional solidified Al-Ni-Co alloy.

  18. Structure of nanocomposites of Al–Fe alloys prepared by mechanical alloying and rapid solidification processing

    Indian Academy of Sciences (India)

    S S Nayak; B S Murty; S K Pabi

    2008-06-01

    Structures of Al-based nanocomposites of Al–Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe2 appeared. Subsequent annealing at 673 K resulted in more Al5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with -Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP.

  19. Etching Behavior of Aluminum Alloy Extrusions

    Science.gov (United States)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  20. Torsional Stability of Aluminum Alloy Seamless Tubing

    Science.gov (United States)

    Moore, R L; Paul, D A

    1939-01-01

    Torsion tests were made on 51ST aluminum-alloy seamless tubes having diameter-to-thickness ratios of from 77 to 139 and length-to-diameter ratios of from 1 to 60. The torsional strengths developed in the tubes which failed elastically (all tubes having lengths greater than 2 to 6 times the diameter) were in most cases within 10 percent of the value indicated by the theories of Donnel, Timoshenko, and Sturm, assuming a condition of simply supported ends.

  1. Aluminum alloy nanosecond vs femtosecond laser marking

    Indian Academy of Sciences (India)

    S Rusu; A Buzaianu; D G Galusca; L Ionel; D Ursescu

    2013-11-01

    Based on the lack of consistent literature publications that analyse the effects of laser marking for traceability on various materials, the present paper proposes a study of the influence of such radiation processing on an aluminum alloy, a vastly used material base within several industry fields. For the novelty impact, femtolaser marking has been carried out, besides the standard commercial nanosecond engraving. All the marks have been analysed using profilometry, overhead and cross-section SEM microscopy, respectively and EDAX measurements.

  2. Deuterium transport and trapping in aluminum alloys

    International Nuclear Information System (INIS)

    A simple model of diffusion and evolution of the density of deuterium in metals is presented. A model of the deuterium evolution in the presence of uniform and nonuniform distributions of traps, as well as perfectly reflecting and partially permeable boundary conditions is discussed. Computers are compared with experimental results describe deuterium distribution after fatigue crack growth of 2219 and 7075 aluminum alloys in a D2O water vapor environment and after ion implantation

  3. Roll bonding of 6061 aluminum alloy plates

    International Nuclear Information System (INIS)

    The roll bonding process is an important application of the solid state welding . in principle, two or more slabs of the materials to be bonded are placed in contact and welded around the edges. then, this assembled set is heated and rolled until the required thickness is obtained. this process is applied to clad the nuclear fuel, with high strength aluminum alloys during fabrication of plate type nuclear fuel elements for research reactors, or to produce many new constructions which have special uses in industrial applications. in the present work, the steps of the hot roll bonding of 6061 aluminum alloy plates were studies by using both microscopic examination and mechanical test namely singe lap shear strength test. also the effect of reduction degree in thickness, the sequence of hot rolling , surface roughness, degassing opening length and holding time on roll bonding process were studied. the results obtained due to variations in the above parameters are discussed with respect to their effects on the roll bonding of 6061 aluminum alloy plates as well as their effects on the specifications of the fuel plates

  4. Thermal coatings for titanium-aluminum alloys

    Science.gov (United States)

    Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

    1993-01-01

    Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

  5. The Technological Improvements of Aluminum Alloy Coloring by Electrolysis

    Institute of Scientific and Technical Information of China (English)

    LI Nai-jun

    2004-01-01

    The technological process of coloring golden-tawny on aluminum alloy by electrolysis was improved in this paper. The optimum composition of electrolyte was found, the conditions of deposition and anodic oxidation by electrolysis were studied. The oxidative membrane on aluminum alloy was satisfying, the colored aluminum alloy by electrolysis is uniformity,bright and beautiful, and the coloring by electrolysis is convenient and no pollution.

  6. The in-situ Ti alloying of aluminum alloys and its application in A356 alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This research has investigated the in-situ Ti alloying of aluminum alloys and its application to A356 alloys and wheels through the evaluation of microstructure and mechanical properties, The results showed that stable titanium content can be obtained by adding a small quantity of TiO2 into electrolyte of pure aluminum. Under this approach, a greater than 95% absorptivity of titanium was achieved, and the microstructure of the specimens was changed to fine equiaxed grains from coarse columnar grains in the pure aluminum. In comparison with the tradition A356 alloys and wheels, the corresponding microstructure in the testing A356 alloys and wheels was finer. Although the tensile strength was similar between the testing and the tradition A356 alloys and wheels, the ductility of the former (testing) is superior to that of the later (tradition), leading to an excellent combination of strength and ductility from the testing alloys and wheels.

  7. Research progress of aluminum alloy automotive sheet and application technology

    Institute of Scientific and Technical Information of China (English)

    Ma Mingtu; You Jianghai; Lu Hongzhou; Wang Zhiwen

    2012-01-01

    Pretrcatment technology is deeply discussed to explain its importance in guaranteeing properties and form- ability of aluminum alloy automotive sheet. Some typical applications of aluminum alloy automotive sheet to automotive industry are listed. Based on the author's knowledge and recognition and research progress presently, the important re- search contents about aluminum alloy automotive sheet are emphasized. Reducing cost and price of sheet and going deeply into application research are the main work for expending the application of aluminum alloy automotive sheet in the automobile.

  8. Simulation on solidification of an Al-Ni alloy under electromagnetic stirring

    Directory of Open Access Journals (Sweden)

    Sha Minghong

    2012-08-01

    Full Text Available The microstructure of Al-Ni alloy has a significant influence on its performance, while electromagnetic stirring is one of the most effective methods for control of solidification structure of Al alloy. To investigate the effect of electromagnetic stirring on the solidification of the ingot, the solidification of the Al-50Ni alloy in vacuum with electromagnetic stirring was described by numerical simulation in this paper; and a three dimensional mathematical model was established. The electromagnetic field was simulated by ANSYS software and the thermal-flow field was simulated by FLUENT software. The coupling between the electromagnetic field and the thermal-flow field was implemented by user-defined subroutines. It is found that the current intensity has significant influences on the fluid flow and the microstructure of the alloy. The simulation results agree well with the experimental results, and the optimum current intensity under the exprimental conditions is 80 A, while the frequency is 50 Hz.

  9. Study on the solidification microstructure in AZ91D Mg alloy after laser surface melting

    International Nuclear Information System (INIS)

    Laser surface melting (LSM) is known to enhance the wear and corrosion resistance of Mg alloys, but its effect on microstructural evolution of Mg alloys is not well understood. An effort has been made to study the effect of rapid solidification following LSM on the microstructural evolution of AZ91D Mg alloy. The results of X-ray diffractometry, scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy indicated that the solidification microstructure in the laser-melted zone was mainly cellular/dendrite structure of primarily α-Mg phase and continuous network of β-Mg17Al12 phase. Numerical prediction of the laser-melted zone suggested that cooling rates increased strongly from the bottom to the top surface in the irradiated regions. An attempt has been made to correlate dendrite cell sizes of the solidification microstructure with the cooling rates in the laser-treated AZ91D Mg alloy.

  10. Modelling of solidification processing and continuous strip casting for copper-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoudi, Jafar [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Materials Processing

    2000-04-01

    An experimental and numerical study was carried out to investigate the solidification process in a copper continuous strip casting process. Heat flow and solidification process has been experimentally studied. Cooling curves during solidification were registered using a thermocouple of type K connected to a data acquisition system. Temperature measurements in the mould and cooling water were also performed. The numerical model considers a generalized set of mass, momentum and heat equations that is valid for the solid, liquid and solidification interval in the cast. A k-{epsilon} turbulence model, produced with the commercial program CFX, is used to analyse the solidification process of pure copper in the mould region of the caster. The fluid flow, temperature and heat flux distributions in the mould region of the caster were computed. The shape and location of the solidification front were also determined. The effects of the parameters such as heat transfer coefficient, casting speed, casting temperature, heat of fusion and specific heat on the shape and location of the solidification front and the heat transport at the mould-cast interface were investigated. The predicted temperature and heat flux distributions were compared with experimental measurements, and reasonable agreement was obtained. The solidification behaviour of pure copper and different copper base alloys has been studied. A series of solidification experiments using DTA furnace, mirror furnace and levitation technique were performed on different copper-base alloys. The undercooling, cooling rates of the liquid and the solid states, solidification times and temperatures were evaluated from the curves. The cooling curves for different samples were simulated using a FEM solidification program. It was found that the calculated values of the heat of fusion were much lower than the tabulated ones. The fraction of solid formed before quenching, in the DTA experiments, has been observed to be much higher

  11. Solidification analysis of a centrifugal atomizer using the Al-32.7wt.% Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, M.G.

    1998-02-23

    A centrifugal atomizer (spinning disk variety) was designed and constructed for the production of spherical metal powders, 100--1,000 microns in diameter in an inert atmosphere. Initial atomization experiments revealed the need for a better understanding of how the liquid metal was atomized and how the liquid droplets solidified. To investigate particle atomization, Ag was atomized in air and the process recorded on high-speed film. To investigate particle solidification, Al-32.7 wt.% Cu was atomized under inert atmosphere and the subsequent particles were examined microscopically to determine solidification structure and rate. This dissertation details the experimental procedures used in producing the Al-Cu eutectic alloy particles, examination of the particle microstructures, and determination of the solidification characteristics (e.g., solidification rate) of various phases. Finally, correlations are proposed between the operation of the centrifugal atomizer and the observed solidification spacings.

  12. Microstructures and properties of aluminum die casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    M. M. Makhlouf; D. Apelian; L. Wang

    1998-10-01

    This document provides descriptions of the microstructure of different aluminum die casting alloys and to relate the various microstructures to the alloy chemistry. It relates the microstructures of the alloys to their main engineering properties such as ultimate tensile strength, yield strength, elongation, fatigue life, impact resistance, wear resistance, hardness, thermal conductivity and electrical conductivity. Finally, it serves as a reference source for aluminum die casting alloys.

  13. In Situ Study of Microstructure Evolution in Solidification of Hypereutectic Al-Si Alloys with Application of Thermal Analysis and Neutron Diffraction

    Science.gov (United States)

    Sediako, Dimitry G.; Kasprzak, Wojciech

    2015-09-01

    Understanding of the kinetics of solid-phase evolution in solidification of hypereutectic aluminum alloys is a key to control their as-cast microstructure and resultant mechanical properties, and in turn, to enhance the service characteristics of actual components. This study was performed to evaluate the solidification kinetics for three P-modified hypereutectic Al-19 pct Si alloys: namely, Al-Si binary alloy and with the subsequent addition of 2.8 pct Cu and 2.8 pct Cu + 0.7 pct Mg. Metallurgical evaluation included thermodynamic calculations of the solidification process using the FactSage™ 6.2 software package, as well as experimental thermal analysis, and in situ neutron diffraction. The study revealed kinetics of solid α-Al, solid Si, Al2Cu, and Mg2Si evolution, as well as the individual effects of Cu and Mg alloying additions on the solidification path of the Al-Si system. Various techniques applied in this study resulted in some discrepancies in the results. For example, the FactSage computations, in general, resulted in 281 K to 286 K (8 °C to 13 °C) higher Al-Si eutectic temperatures than the ones recorded in the thermal analysis, which are also ~278 K (~5 °C) higher than those observed in the in situ neutron diffraction. None of the techniques can provide a definite value for the solidus temperature, as this is affected by the chosen calculation path [283 K to 303 K (10 °C to 30 °C) higher for equilibrium solidification vs non-equilibrium] for the FactSage analysis; and further complicated by evolution of secondary Al-Cu and Mg-Si phases that commenced at the end of solidification. An explanation of the discrepancies observed and complications associated with every technique applied is offered in the paper.

  14. Rapid Solidification Effects on the Development of an HCP Matrix in a Co-20Cr Alloy

    Science.gov (United States)

    Ramirez-Ledesma, A. L.; Lopez, H. F.; Juarez-Islas, J. A.

    2016-06-01

    In the present work, it is experimentally found that rapid solidification enhances significantly the γ-FCC → ɛ-HCP transformation by generating a high density of ɛ-martensite embryo nucleating defects in a Co-20Cr alloy. Conclusive evidence based on X-ray diffraction determinations combined with SEM and TEM observations indicates that the formation of athermal ɛ-martensite is strongly influenced by rapid solidification conditions ( i.e., up to 89.6 vol pct).

  15. Numerical calculation on temperature field of FGH95 alloy droplet during rapid solidification

    Institute of Scientific and Technical Information of China (English)

    Huanming Chen; Benfu Hu

    2003-01-01

    The temperature field of FGH95 alloy droplet atomized by plasma rotating electrode processing (PREP) during solidifica-tion has been calculated through numerical analysis based on equivalent sensible heat capacity method. And thus the relational cul-ves among temperature gradient of solid-liquid interface, moving velocity of solid-liquid interface and solid fraction during solidifi-cation have been presented. The results indicate that the relation between average temperature gradient of solid-liquid interface anddroplet size, and the relation between average moving velocity of solid-liquid interface and droplet size can be expressed during solidification.

  16. Laser perforation of aluminum alloy sheet

    Science.gov (United States)

    Migliore, Leonard; Nazary, George

    2010-02-01

    Recent advances in the design of gain modules for diode-pumped solid-state lasers have allowed the manufacture of high-powered Q-switched products. The high available pulse energy and good mode quality enable highly efficient harmonic conversion, enabling the generation of several hundred watts of average power at a wavelength of 532nm. Among the applications for which this class of product may be suited is the rapid drilling of small-diameter holes in aluminum sheet. To investigate this application, plates of several aluminum alloys were drilled under a variety of conditions. The drilled plates were sectioned and subjected to analysis by optical metallography. The initial results indicate ways in which the process may be optimized.

  17. Time-Resolved In Situ Measurements During Rapid Alloy Solidification: Experimental Insight for Additive Manufacturing

    Science.gov (United States)

    McKeown, Joseph T.; Zweiacker, Kai; Liu, Can; Coughlin, Daniel R.; Clarke, Amy J.; Baldwin, J. Kevin; Gibbs, John W.; Roehling, John D.; Imhoff, Seth D.; Gibbs, Paul J.; Tourret, Damien; Wiezorek, Jörg M. K.; Campbell, Geoffrey H.

    2016-03-01

    Additive manufacturing (AM) of metals and alloys is becoming a pervasive technology in both research and industrial environments, though significant challenges remain before widespread implementation of AM can be realized. In situ investigations of rapid alloy solidification with high spatial and temporal resolutions can provide unique experimental insight into microstructure evolution and kinetics that are relevant for AM processing. Hypoeutectic thin-film Al-Cu and Al-Si alloys were investigated using dynamic transmission electron microscopy to monitor pulsed-laser-induced rapid solidification across microsecond timescales. Solid-liquid interface velocities measured from time-resolved images revealed accelerating solidification fronts in both alloys. The observed microstructure evolution, solidification product, and presence of a morphological instability at the solid-liquid interface in the Al-4 at.%Cu alloy are related to the measured interface velocities and small differences in composition that affect the thermophysical properties of the alloys. These time-resolved in situ measurements can inform and validate predictive modeling efforts for AM.

  18. Structural and physicomechanical properties of directionally crystallized aluminum-silicon alloys

    Science.gov (United States)

    Nikanorov, S. P.; Derkachenko, L. I.; Kardashev, B. K.; Korchunov, B. N.; Osipov, V. N.; Shpeizman, V. V.

    2013-06-01

    Aluminum-silicon alloys (from 8 to 25 wt % Si) have been prepared by directional crystallization of shaped samples by the Stepanov growth at a solidification rate of 103 μm s-1. The dependences of the microhardness, Young's modulus, internal friction, yield stress, and ultimate tensile stress of the alloys on the silicon content have been studied. It has been shown that the ultimate tensile stress has a maximum, and the yield stress has a kink at 15 wt % Si; the composition corresponds to the eutectic composition at the solidification rate used. The silicon content in the eutectics increases with an increase in the solidification rate. The increase in the ultimate tensile stress is explained by an increase in the volume fraction of the more strength fine-crystalline structure of the eutectics as a result of the decrease in the volume fraction of more plastic dendrites of the primary crystals of the α-Al solid solution. The decrease in the ultimate tensile stress of the hypereutectic alloy is determined by the increase in the volume fraction of brittle primary silicon crystals of various shapes.

  19. The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

    Science.gov (United States)

    Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

    1983-01-01

    As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

  20. Precipitate-Accommodated Plasma Nitriding for Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    Patama Visittipitukul; Tatsuhiko Aizawa; Hideyuki Kuwahara

    2004-01-01

    Reliable surface treatment has been explored to improve the strength and wear resistance of aluminum alloy parts in automotives. Long duration time as well as long pre-sputtering time are required for plasma nitriding of aluminum or its alloys only with the thickness of a few micrometers. New plasma inner nitriding is proposed to realize the fast-rate nitriding of aluminum alloys. Al-6Cu alloy is employed as a targeting material in order to demonstrate the effectiveness of this plasma nitriding. Mechanism of fast-rate nitriding process is discussed with consideration of the role of Al2Cu precipitates.

  1. Using Neural Networks to Predict the Hardness of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    B. Zahran

    2015-02-01

    Full Text Available Aluminum alloys have gained significant industrial importance being involved in many of the light and heavy industries and especially in aerospace engineering. The mechanical properties of aluminum alloys are defined by a number of principal microstructural features. Conventional mathematical models of these properties are sometimes very complex to be analytically calculated. In this paper, a neural network model is used to predict the correlations between the hardness of aluminum alloys in relation to certain alloying elements. A backpropagation neural network is trained using a thorough dataset. The impact of certain elements is documented and an optimum structure is proposed.

  2. Solidification structure and dispersoids in rapidly solidified Ti-Al-Sn-Zr-Er-B alloys

    International Nuclear Information System (INIS)

    The microstructure of melt extracted and melt spun titanium alloys containing erbium and boron revealed a duplex solidification structure of columnar grains leading to equiaxed and dendritic structures near the free surface of melt extracted and melt spun alloys. The solidification structure was revealed by apparent boride segregation to cellular, interdendritic and grain boundaries. Precipitation of needle or lath-like TiB particles occurred adjacent to Er/sub 2/O/sub 3/ dispesoid particles in as-rapidly solidified ribbon

  3. Thin sample alloy solidification in electromagnetic driven convection

    OpenAIRE

    Kao, A.; Shevchenko, N.; Roshchupinka, O.; Eckert, S.; Pericleous, Koulis

    2015-01-01

    During the directional solidification of Ga-In25%wt., density variations in the liquid cause plumes of solute to be ejected from the interface through natural convection. This can lead to the formation of chimneys during solidification and ultimately freckles. The application of external magnetic fields can be used to suppress these plumes. Two magnetic systems are considered. The first is a rotating magnetic wheel, which provides conditions analogous to forced convection at the solidificatio...

  4. Cooling Rate Determination in Additively Manufactured Aluminum Alloy 2219

    Science.gov (United States)

    Brice, Craig A.; Dennis, Noah

    2015-05-01

    Metallic additive manufacturing processes generally utilize a conduction mode, welding-type approach to create beads of deposited material that can be arranged into a three-dimensional structure. As with welding, the cooling rates in the molten pool are relatively rapid compared to traditional casting techniques. Determination of the cooling rate in the molten pool is critical for predicting the solidified microstructure and resultant properties. In this experiment, wire-fed electron beam additive manufacturing was used to melt aluminum alloy 2219 under different thermal boundary conditions. The dendrite arm spacing was measured in the remelted material, and this information was used to estimate cooling rates in the molten pool based on established empirical relationships. The results showed that the thermal boundary conditions have a significant effect on the resulting cooling rate in the molten pool. When thermal conduction is limited due to a small thermal sink, the dendrite arm spacing varies between 15 and 35 µm. When thermal conduction is active, the dendrite arm spacing varies between 6 and 12 µm. This range of dendrite arm spacing implies cooling rates ranging from 5 to 350 K/s. Cooling rates can vary greatly as thermal conditions change during deposition. A cooling rate at the higher end of the range could lead to significant deviation from microstructural equilibrium during solidification.

  5. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet

    Science.gov (United States)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.

    1993-01-01

    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  6. Processing of Aluminum Alloys Containing Displacement Reaction Products

    OpenAIRE

    Stawovy, Michael Thomas

    1998-01-01

    Aluminum and metal-oxide powders were mixed using mechanical alloying. Exothermic displacement reactions could be initiated in the powders either by mechanical alloying alone or by heat treating the mechanically alloyed powders. Exponential relationships developed between the initiation time of the reaction and the mechanical alloying charge ratio. The exponential relationships were the result of changes in the intensity and quantity of collisions occurring during mechanical alloying. Di...

  7. Eutectic Solidification in Al-13.0%Si Alloys with Combined Addition of Strontium and Boron

    Institute of Scientific and Technical Information of China (English)

    Hengcheng Liao; Ke Ding; Juanjuan Bi; Min Zhang; Huipin Wang; Lei Zhao

    2009-01-01

    The influence of addition of boron (B) on eutectic solidification in a near-eutectic AI-13.0%Si alloy modified with strontium (Sr) was investigated using thermal analysis and macro/microstructure observation. Addition of B in the Sr-modified alloy leads to a considerable increase in nucleation temperature (Tn, the minimum temperature prior to recalescence (TM) and growth temperature (TG). In the Sr-modified alloy, nucleation of eutectic might originate at the heterogeneous sites on the mold wall or in the melt near the wall, and eutectic solidification proceeds gradually towards the center, controlled by undercooling of melt. However, with addition of B in the Sr-modified alloy, undercooling required for eutectic nucleation became small, and hence eutectic solidification might occur almost simultaneously within whole casting, controlled by amount of heterogeneous sites. With excessive addition of B in the Sr-modified alloy, nucleation of eutectic grains was explosive within the whole casting and the power of Sr on eutectic solidification was completely poisoned.

  8. The Role of Particles in Fatigue Crack Propagation of Aluminum Matrix Composites and Casting Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    Zhenzhong CHEN; Ping HE; Liqing CHEN

    2007-01-01

    Fatigue crack propagation (FCP) behaviors were studied to understand the role of SiC particles in 10 wt pct SiCp/A2024 composites and Si particles in casting aluminum alloy A356. The results show that a few particles appeared on the fracture surfaces in SiCp/Al composites even at high AK region, which indicates that cracks propagated predominantly within the matrix avoiding SiC particles due to the high strength of the particles and the strong particle/matrix interface. In casting aluminum alloy, Si particle debonding was more prominent.Compared with SiCp/Al composite, the casting aluminum alloy exhibited lower FCP rates, but had a slight steeper slope in the Paris region. Crack deflection and branching were found to be more remarkable in the casting aluminum alloy than that in the SiCp/Al composites, which may be contributed to higher FCP resistance in casting aluminum alloy.

  9. High Magnetic Field-Induced Formation of Banded Microstructures in Lamellar Eutectic Alloys During Directional Solidification

    Science.gov (United States)

    Li, Xi; Fautrelle, Yves; Gagnoud, Annie; Ren, Zhongming; Moreau, Rene

    2016-06-01

    The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae.

  10. Some effects of solidification kinetics on microstructure formation in aluminium-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H. [Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2005-12-15

    The development of rapid solidification technologies and their effects has provided a stimulus to seek a deeper understanding of the mechanisms by which kinetics determine solidification microstructure formation, including its scale, morphology and phase constitution. Successful application of model predictions to real situations involves coupling of heat and fluid flow considerations to the thermodynamics and kinetics of competing solidification reactions. A key element in this competition is the formation temperature of the contending constituents and their morphologies which is beyond the present scope of experimental determination at the extremes of most rapid solidification processes. The present contribution focuses on recent work on measurements of formation temperature of constituents in Al-based alloys during Bridgman solidification for comparison with model predictions. Together with associated microstructural observations, the results indicate control by heterogeneous nucleation in the case of polygonal primary silicon in hypereutectic Al-Si alloys, while competitive growth is controlling for aluminide dendrites in Al-Fe, Al-Ni and Al-Ce or Al-La alloys, for which measured tip undercoolings accord well with values calculated from dendrite growth models. Also, values of equilibrium eutectic temperature obtained by extrapolation to zero growth velocity of growth temperatures in such systems agree well with reliable values obtained by other methods and values of kinetic constants for dendrites and eutectics derived from measured velocities for extinction of the dendritic constituent are shown to be in good accord with direct measurements.

  11. Some effects of solidification kinetics on microstructure formation in aluminium-base alloys

    International Nuclear Information System (INIS)

    The development of rapid solidification technologies and their effects has provided a stimulus to seek a deeper understanding of the mechanisms by which kinetics determine solidification microstructure formation, including its scale, morphology and phase constitution. Successful application of model predictions to real situations involves coupling of heat and fluid flow considerations to the thermodynamics and kinetics of competing solidification reactions. A key element in this competition is the formation temperature of the contending constituents and their morphologies which is beyond the present scope of experimental determination at the extremes of most rapid solidification processes. The present contribution focuses on recent work on measurements of formation temperature of constituents in Al-based alloys during Bridgman solidification for comparison with model predictions. Together with associated microstructural observations, the results indicate control by heterogeneous nucleation in the case of polygonal primary silicon in hypereutectic Al-Si alloys, while competitive growth is controlling for aluminide dendrites in Al-Fe, Al-Ni and Al-Ce or Al-La alloys, for which measured tip undercoolings accord well with values calculated from dendrite growth models. Also, values of equilibrium eutectic temperature obtained by extrapolation to zero growth velocity of growth temperatures in such systems agree well with reliable values obtained by other methods and values of kinetic constants for dendrites and eutectics derived from measured velocities for extinction of the dendritic constituent are shown to be in good accord with direct measurements

  12. Directional solidification studies in Ni-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Je-hyun

    1993-05-01

    Three solid phases are involved in the phase equilibria of the intermetallic compound Ni{sub 3}Al near its melting point, {beta}, {gamma}{prime}(Ni{sub 3}Al), and {gamma}. The generally-accepted phase diagram involves a eutectic reaction between {beta}{prime} and {gamma}, but some recent studies agree with an older diagram due to Schramm, which has a eutectic reaction between the {beta} and {gamma}{prime} phases. The phase equilibria near Ni{sub 3}Al compositions was evaluated using quenched directional solidification experiments, that preserve the microstructures tonned at the solidification front, and using diffusion couple experiments. These experiments show that eutectic forms between {beta} and {gamma}{prime} phases, as in the Schramm diagram. Growth and phase transformations of these three phases are also studied in the directional solidification experiments. Microstructure analysis shows that etching of Ni{sub 3}Al({gamma}{prime}) is very sensitive to small composition variations and crystallographic orientation changes. The eutectic solidification study confirms that the equilibrium eutectic is {gamma}{prime}+{beta}, and that the metastable {gamma}+{beta} eutectic might be also produced in this system according to the impurities, solidification rates, and composition variations.

  13. XRMON-SOL: Isothermal equiaxed solidification of a grain refined Al-20 wt%Cu alloy

    Science.gov (United States)

    Murphy, A. G.; Mathiesen, R. H.; Houltz, Y.; Li, J.; Lockowandt, C.; Henriksson, K.; Zimmermann, G.; Melville, N.; Browne, D. J.

    2016-04-01

    A novel isothermal solidification furnace (XRMON-SOL) has been developed for operation under terrestrial and microgravity conditions, using aluminium-based alloys, in conjunction with real-time in situ X-radiography. The furnace is scheduled to fly on board the MASER 13 Sounding Rocket with a view to investigating isothermal equiaxed solidification under microgravity conditions. The present work provides details of the furnace design as well as detailed analysis of pre-flight terrestrial solidification experiments investigating nucleation and growth characteristics of a thin sample of grain refined Al-20 wt%Cu alloy isothermally solidified at a constant cooling rate of -0.05 K/s. Measurements of nucleation density, nucleation undercooling, grain orientation, grain envelope evolution, primary tip growth velocities, and equiaxed grain interactions are provided. Although the effects of gravity were minimised by choice of sample orientation, we show that such effects can only be eliminated in a microgravity environment.

  14. Finite element simulations of thermosolutal convection in vertical solidification of binary alloys

    Science.gov (United States)

    Heinrich, J. C.; Felicelli, S.

    1989-01-01

    Dendritic vertical solidification of a binary alloy is modeled using the finite element method to assess the effect of thermosolutal convection in macrosegregation. The mathematical model assumes steady-state solidification with a planar, undeformable surface defined by the dendrite tips and the eutectic isotherm. The dendritic region is assumed to advance at a constant solidification velocity v. The stability of the modeled system has been investigated and nonlinear calculations performed that show finger-like convection when the system is unstable. Results for lead-tin alloys show that when the system is unstable, convection is only significant in the uppermost part of the mush and is entirely driven by convection in the bulk fluid.

  15. Solidification Features of Ti45Al Alloys with Different Boron Addition

    Institute of Scientific and Technical Information of China (English)

    Weidong Wang; Yingche Ma; Bo Chen; Ming Gao; Kui Liu; Yiyi Li

    2009-01-01

    The effects of boron on the solidification behaviors of Ti45AlxB alloys were studied by high temperature samples. These samples were melted at 1823 K, followed by cooling to the designated temperature, and then quickly water-quenched to preserve the solidification features. Optical microscopy and scanning electron microscopy analysis shows that the solidus temperature of Ti45AI was really reduced by 20 K when adding 0.8 at. pct B, and it was also observed that boride precipitated before the appearance of β phase. Besides, solidification structure confirmed that B addition does not obviously refine β phase, α grain refinement by certain amount of B in alloy probably clarifies the mechanism of B refining lamellar microstructure at room temperature.

  16. Modelling of convection during solidification of metal and alloys

    Indian Academy of Sciences (India)

    A K Singh; R Pardeshi; B Basu

    2001-02-01

    The role of convection during solidification is studied with the help of a mathematical model. The effect of various mush models on convection and consequent macrosegregation is examined with the help of numerical simulations. The predicted macrosegregation profiles are compared with published experimental data. Subsequently, the importance of proper auxiliary relationship for thermo-solutal coupling in the mushy region is highlighted through some careful numerical simulations. Finally, the role of material parameters on double-diffusive convection is illustrated through comparative study of solidification of aqueous ammonium chloride, iron-carbon and lead-tin binary systems. Important results of these studies are presented and discussed.

  17. Solidification microstructure of AZ91D Mg alloy after laser surface melting

    Science.gov (United States)

    Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

    2010-11-01

    The solidification microstructure plays a critical role in determining the surface properties of laser-treated magnesium alloys. The purpose of this paper is to study the solidification microstructures of AZ91D Mg alloy following millisecond- and nanosecond-pulse Nd:YAG laser irradiation. The solidification microstructural evolution of laser-melt AZ91D Mg alloy was investigated using X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectrometer and transmission electron microscopy. Much refined α-Mg phase and β-Mg17Al12 intermetallics were observed in the microstructure after laser surface melting. Periodic and successive structure was observed in the millisecond irradiated surface and the melt depth was more than 100 μm. The solidification microstructure was mainly cellular/dendrite structures together with a large number of β-Mg17Al12 nano-particles. Micron holes were found in the nanosecond irradiated surface and the melt depth was shallow at 50 μm. Millisecond-pulse Nd:YAG laser was found to be more suitable for Mg alloy surface treatment due to sufficient melt depth.

  18. Effect of phosphor addition on eutectic solidification and microstructure of an Al-13%Si alloy

    Directory of Open Access Journals (Sweden)

    Liao Hengcheng

    2011-11-01

    Full Text Available As the refiner or modifier, the master alloys containing high concentration phosphor are widely used in preparing eutectic or hypereutectic Al-Si alloys. To study the effect of phosphor addition on the eutectic solidification and microstructure of the Al-13%Si alloy, an investigation has been undertaken by means of thermal analysis and micro/macro-structure observation. Results indicate that addition of phosphor in near eutectic Al-Si alloy promotes the nucleation of eutectic but has little refinement impact on primary Si particles as expected. Conversely, both primary Si particles and eutectic Si flakes become slightly coarser in P-rich alloys. The coarsening of eutectic Si flakes ties closely to the increased eutectic growth temperature with phosphor addition. The eutectic solidification of the alloy proceeds from the near mold zone towards the center, and it is also found that a few independent nucleation regions emerge in liquid at the solidification front due to the addition of phosphor.

  19. Electrodeposition of magnesium and magnesium/aluminum alloys

    Science.gov (United States)

    Mayer, A.

    1988-01-21

    Electrolytes and plating solutions for use in processes for electroplating and electroforming pure magnesium and alloys of aluminum and magnesium and also electrodeposition processes. An electrolyte of this invention is comprised of an alkali metal fluoride or a quaternary ammonium halide, dimethyl magnesium and/or diethyl magnesium, and triethyl aluminum and/or triisobutyl aluminum. An electrolyte may be dissolved in an aromatic hydrocarbon solvent to form a plating solution. The proportions of the component compounds in the electrolyte are varied to produce essentially pure magnesium or magnesium/aluminum alloys having varying selected compositions.

  20. Studies on the effect of vibration on hot cracking and Grain size in AA7075 Aluminum alloy Welding

    Directory of Open Access Journals (Sweden)

    BALASUBRAMANIAN.K

    2011-01-01

    Full Text Available The aim of this present study is to investigate the vibration effect which is applied during Gas tungsten Arc welding (GTAW welding in order to improve the quality of high strength Aluminum alloy weldment. An important metallurgical difficulty in arc welding of high strength aluminum alloys is formation of hot cracking. When Aluminum alloy is welded by GTAW process, weld fusion zone shows coarse columnar grains during weld metal solidification. This often leads to poor resistance to hot cracking. In this work, an attempt is made to reduce the hot cracking and to refine the fusion zone grains in welding of aluminum alloys through vibratory treatment. The material used for the investigation is AA7075 aluminum alloy, which is highly prone for hot cracking. Vibratory treatment was carried out in the frequency range of 100Hz to 2050Hz. Weldments made with and without vibratory treatment were compared using weld cracking tests and other characterization tests like micro structural analysis, hardness measurements. Test results show that by applying vibratory treatment, hot cracking can be largely controlled in arc welding.

  1. Friction Pull Plug Welding in Aluminum Alloys

    Science.gov (United States)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  2. Diffusion Bonding and Characterization of a Dispersion Strengthened Aluminum Alloy

    Science.gov (United States)

    Cooke, Kavian Omar

    Aluminum metal matrix composites (Al-MMC's) containing silicon carbide or alumina particle reinforcements are used extensively in automotive and aircraft industries. The addition of a reinforcing phase has led to significant improvements in the mechanical properties of these alloys. However, despite substantial improvements in the properties, the lack of a reliable joining method has restricted their full potential. The differences in physical and metallurgical properties between the ceramic phase and the Al-MMC, prevents the successful application of the fusion welding processes, conventionally used for joining monolithic aluminum alloys. Therefore, alternative techniques that prevent microstructural changes in the base metal need to be developed. In this study, the transient liquid phase diffusion bonding and eutectic bonding of a particle reinforced Al 6061-MMC was investigated to identify a method that could control particle segregation within the joint and increase the final joint strength. The results showed that TLP bonding using Ni-foil was possible at 600°C for 10 minutes using a pressure of 0.01 MPa. However, characterization of the bond interface showed a wide particle segregated zone due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The presence of this particle segregated zone was shown to cause low joint strengths. In order to overcome these problems, TLP bonding was performed using electrodeposited coatings of Ni and Ni-Al 2O3 as a way of controlling the volume of eutectic liquid formed at the joint. Theoretical and experimental work showed that the use of thin coatings was successful in reducing the width of the segregated zone formed at the joint and this had the effect of increasing joint shear strength values. Furthermore, lower bonding temperature could also be used as a method of reducing particle segregation and therefore, a Cu-Sn interlayer was used to form a eutectic bond. The

  3. A 3-D coupled hydromechanical granular model for simulating the constitutive behavior of metallic alloys during solidification

    OpenAIRE

    Sistaninia, M.; Phillion, A. B.; Drezet, J. -M.; Rappaz, M.

    2012-01-01

    A three-dimensional (3-D) coupled hydromechanical granular model has been developed and validated to directly predict, for the first time, hot tear formation and stress strain behavior in metallic alloys during solidification. This granular model consists of four separate 3-D modules: (i) the solidification module is used to generate the solid liquid geometry at a given solid fraction; (ii) the fluid flow module (FFM) is used to calculate the solidification shrinkage and deformation-induced p...

  4. Ultrasound assisted solidification process of ternary Cu–Sn–Sb alloy

    Directory of Open Access Journals (Sweden)

    Zhai Wei

    2016-02-01

    Full Text Available It is well-known that the application of ultrasound during liquid to solid transitions for alloys can refine the solidification microstructure and thus improves the mechanical properties. However, most published work focuses on single phase dendritic growth, whereas little has been conducted on the multiphase alloys with complicated phase transformations during solidification. In this work, the solidification process of ternary Cu40Sn45Sb15 alloy was realized within intensive ultrasonic field with a resonant frequency of 20 kHz and ultrasound power from 0 W to 1000 W. The ultrasound refines the size of the primary ε(Cu3Sn intermetallic compound by two orders of magnitudes. If the ultrasound power increases to 1000 W, η(Cu6Sn5 phase nucleates and grows directly from parent liquid phase without the occurrence of peri-eutectic reaction on the top of the alloy sample where the ultrasound intensity is sufficiently high. These microstructural variations lead to the enhancement of compressive strength and elasticity modulus of ternary Cu40Sn45Sb15 alloy.

  5. Solidification microstructures and mechanical properties of NbAl3-based alloys

    International Nuclear Information System (INIS)

    This paper reports on the effects of certain alloying additions, namely, copper, iron and nickel, on the solidification behavior, phase constitution and mechanical properties of the brittle intermetallic compound NbAl3 that have been examined. The microstructures of the various alloys studied were coarse, heavily segregated, and contained considerable shrinkage porosity after arc casting. Differential thermal analysis indicated the presence of large solidification ranges consistent with the microstructural features. Attempts to reduce the scale of the microstructures by either rapid solidification and/or subsequent thermal and thermomechanical processing were only marginally successful. A preliminary assessment of the toughnesses of the alloys, using microhardness indentation and qualitative impact tests, indicated that, although the microstructures were coarse and complex, some toughening was achieved in the ternary alloys this was attributed to the presence of second phases which cause crack deflection and/or bridging. In no instances was the tetragonal DO22 to cubic Li2 structural modification, as achieved in the isomorphous TiAl3 system with similar alloying additions, observed, consistent with the recent predictions by Carlsson and Meschter

  6. Thixoforming of an ECAPed Aluminum A356 Alloy: Microstructure Evolution, Rheological Behavior, and Mechanical Properties

    Science.gov (United States)

    Campo, Kaio Niitsu; Zoqui, Eugênio José

    2016-04-01

    Thixoforming depends upon three aspects: (a) solid to liquid transformation; (b) size and morphology of the remaining solid phase in the semisolid state, and (c) the effect of both input factors on rheology of the semisolid slurry. The aluminum A356 alloy presents an ideal solid to liquid transformation, but the solidification process generates coarse aluminum dendrites surrounded by eutectic. In this regard, Equal Channel Angular Pressing (ECAP) has great potential as a method for manufacturing thixotropic raw material due to its grain refining effect. Therefore, the microstructure evolution and rheological behavior in the semisolid state of an ECAPed aluminum A356 alloy were investigated. Samples were heated up to 853 K (580 °C) and held for 0, 30, 60, 90, 210, and 600 seconds at this temperature. The isothermal heat treatment caused the globularization of the solid phase without any significant microstructure coarsening. Compression tests were carried out at the same temperature and holding times using an instrumented mechanical press. Apparent viscosities values close to 250 Pa s were obtained, revealing the exceptional rheological behavior of the produced samples. The thixoformed material also presented good mechanical properties, with high yield and ultimate tensile strength values (YS = 110/122 MPa, UTS = 173/202), and good ductility (E = 6.9/7.5 pct). These results indicate that the production of the A356 alloy via the ECAP process increases its thixoformability.

  7. Effect of liquid-liquid structure transition on solidification of Sn-Bi alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effect of the liquid-liquid structure transition(L-LST) on the solidification behaviors and morphologies of Sn-Bi alloys was studied further. The results show that the undercooling of the primary and eutectic phase increases and the microstructure becomes finer after solidifying from the melt experiencing the L-LST. In the meantime, in hypoeutectic alloy, when solidifying from the melt experiencing the L-LST, the morphology of primary phase changes from the fir-tree crystal into the equiaxed crystal, and less primary phase and more eutectic structure are observed. Moreover, in eutectic alloy, the spacing of eutectic phase decreases markedly. These investigations would be beneficial to further exploration of the correlation between the melt structure and the micro mechanism of solidification.

  8. Measurement of Thermodynamic Properties of Titanium Aluminum Alloys

    Science.gov (United States)

    Mehrotra, Gopal

    1995-01-01

    This final report is a summary of the work done by Professor Mehrotra at NASA Lewis Research Center. He has worked extensively on the measurement of thermodynamic properties of titanium aluminum alloys over the past six years.

  9. The development of recycle-friendly automotive aluminum alloys

    Science.gov (United States)

    Das, Subodh K.; Green, J. A. S.; Kaufman, J. Gilbert

    2007-11-01

    The continuing growth of aluminum alloy usage in transportation applications, notably passenger automobiles and minivans, and the demonstrated economic benefits of recycling aluminum-rich vehicles increase the need to seriously consider the desirability of designing recycling-friendly alloys. This article focuses on that aspect of the recycling process for passenger vehicles. The goals are to illustrate the opportunities afforded by identifying and taking full advantage of potential metal streams in guiding the development of new alloys that use those streams. In speculating on several possible aluminum recovery practices and systems that might be used in recycling passenger vehicles, likely compositions are identified and preliminary assessments of their usefulness for direct recycling are made. Specific compositions for possible new recycle-friendly alloys are suggested. In addition, recommendations on how the aluminum enterprise, including industry, academia, and government, can work together to achieve the aggressive but important goals described here are discussed.

  10. Paint-Bonding Improvement for 2219 Aluminum Alloy

    Science.gov (United States)

    Daech, Alfred F.; Cibula, Audrey Y.

    1987-01-01

    Bonding of adhesives and primers to 2219 aluminum alloy improved by delaying rinse step in surface-treatment process. Delaying rinse allows formation of rougher surface for stronger bonding and greater oxide buildup.

  11. Prediction of Solidification and Microstructure of Inconel Alloy Using Numerical Simulation

    International Nuclear Information System (INIS)

    Test castings of Inconel 713LC nickel alloy were prepared by pouring into shell molds in vacuum furnace. The temperature was experimentally measured in the course of solidification and cooling, and the structure was evaluated in as-cast condition. Applying thermal insulation of shells, the dependence of the structure of castings on cooling rate was monitored on test castings. The solidification pattern was solved numerically, using the ProCAST simulation program. Parameters for the simulation of as-cast structure were sought using the CAFÉ module of the ProCAST program. Calculation parameters were established with the experimentally determined temperature curves and structure.

  12. Phase field modeling of multiple dendrite growth of AI-Si binary alloy under isothermal solidification

    Institute of Scientific and Technical Information of China (English)

    Sun Qiang; Zhang Yutuo; Cui Haixia; Wang Chengzhi

    2008-01-01

    Phase field method offers the prospect of being able to perform realistic numerical experiments on dendrite growth in metallic systems. In this study, the growth process of multiple dendrites in Ai-2-mole-%-Si binary alloy under isothermal solidification was simulated using phase field model. The simulation results showed the impingement of arbitrarily oriented crystals and the competitive growth among the grains during solidification. With the increase of growing time, the grains begin to coalesce and impinge the adjacent grains. When the dendrites start to impinge, the dendrite growth is obviously inhibited.

  13. The Effect of Applied Pressure During Feeding of Critical Cast Aluminum Alloy Components With Particular Reference to Fatigue Resistance

    Energy Technology Data Exchange (ETDEWEB)

    J.T. Berry; R. Luck; B. Zhang; R.P. Taylor

    2003-06-30

    the medium to long freezing range alloys of aluminum such as A356, A357, A206, 319 for example are known to exhibit dispersed porosity, which is recognized as a factor affecting ductility, fracture toughness, and fatigue resistance of light alloy castings. The local thermal environment, for example, temperature gradient and freezing from velocity, affect the mode of solidification which, along with alloy composition, heat treatment, oxide film occlusion, hydrogen content, and the extent to which the alloy contracts on solidification, combine to exert strong effects on the porosity formation in such alloys. In addition to such factors, the availability of liquid metal and its ability to flow through the partially solidified casting, which will be affect by the pressure in the liquid metal, must also be considered. The supply of molten metal will thus be controlled by the volume of the riser available for feeding the particular casting location, its solidification time, and its location together with any external pressure that might be applied at the riser.

  14. Al-Si-Re Alloys Cast by the Rapid Solidification Process / Stopy Al-Si-Re Odlewane Metodą Rapid Solidification

    Directory of Open Access Journals (Sweden)

    Szymanek M.

    2015-12-01

    Full Text Available The aim of the studies described in this article was to present the effect of rare earth elements on aluminium alloys produced by an unconventional casting technique. The article gives characteristics of the thin strip of Al-Si-RE alloy produced by Rapid Solidification (RS. The effect of rare earth elements on structure refinement, i.e. on the size of near-eutectic crystallites in an aluminium-silicon alloy, was discussed. To determine the size of crystallites, the Scherrer X-ray diffraction method was used. The results presented capture relationships showing the effect of variable casting parameters and chemical composition on microstructure of the examined alloys. Rapid Solidification applied to Al-Si alloys with the addition of mischmetal (Ce, La, Ne, Pr refines their structure.

  15. A phase-field model for the solidification of multicomponent and multiphase alloys

    Science.gov (United States)

    Qin, R. S.; Wallach, E. R.; Thomson, R. C.

    2005-05-01

    A phase-field model for the simulation of solidification of a multicomponent and multiphase systems has been developed, which is based on an earlier developed multiphase field model for binary alloys and a phase-field multicomponent model for single-solid-phase systems. After incorporation with alloy thermodynamics and commercial software for the calculation of phase equilibria, the model has been implemented to study the microstructural evolution of an Al-11.5 mol% Si-0.9 mol% Cu-0.4 mol% Fe alloy. Numerical results for the morphological evolution of primary aluminium, silicon and AlFeSi intermetallic phases agree with experimental observations very well.

  16. Solidification Effects in MAR-M246(Hf) Alloy

    Science.gov (United States)

    Johnston, M. H.; Parr, R. A.

    1987-01-01

    Fatigue properties degraded with crystallographic orientations greater than 10 degrees from {001} axis. Influence of solidification and heat-treatment parameters on structure and fatigue properties of nickel-based superalloy MAR-M246(Hf) described in 24-page report. Superalloys have high strength and corrosion resistance at temperatures up to 1,400 degrees C; their uses range from petrochemical equipment to marine, industrial, aircraft, and vehicular gas turbines.

  17. Optimization of Squeeze Casting for Aluminum Alloy Parts

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Qingming Chang; Yulong Zhu

    2002-07-30

    This study was initiated with the installation of a new production size UBE 350 Ton VSC Squeeze Casting system in the Metal Casting Laboratory at Case Western University. A Lindberg 75k W electrical melting furnace was installed alongside. The challenge of installation and operation of such industrial-size equipment in an academic environment was met successfully. Subsequently, a Sterling oil die heater and a Visi-Track shot monitoring system were added. A significant number of inserts were designed and fabricated over the span of the project, primarily for squeeze casting different configurations of test bars and plates. A spiral ''ribbon insert'' for evaluation of molten metal fluidity was also fabricated. These inserts were used to generate a broad range of processing conditions and determine their effect on the quality of the squeeze cast parts. This investigation has studied the influence of the various casting variables on the quality of indirect squeeze castings primarily of aluminum alloys. The variables studied include gating design, fill time and fill patter, metal pressure and die temperature variations. The quality of the die casting was assessed by an analysis of both their surface condition and internal soundness. The primary metal tested was an aluminum 356 alloy. In addition to determining the effect of these casting variables on casting quality as measured by a flat plate die of various thickness, a number of test bar inserts with different gating designs have been inserted in the squeeze casting machine. The mechanical properties of these test bars produced under different squeeze casting conditions were measured and reported. The investigation of the resulting properties also included an analysis of the microstructure of the squeeze castings and the effect of the various structural constituents on the resulting properties. The main conclusions from this investigation are as follows: The ingate size and shape are very important

  18. Effect of Microalloying on Wettability, Oxidation and Solidification Morphology of Sn-9Zn Alloy

    Institute of Scientific and Technical Information of China (English)

    Wei Xiuqin; Huang Huizhen; Zhou Lang; Zhang Meng

    2005-01-01

    Eutectic alloy Sn-9Zn is an attractive candidate for lead-free solders. However, its wettability to copper is poor thus,its development was limited. Effects of less than 1% (mass fraction) additions of mischmetal consisting mainly of La and Ce, heavy rare earth Y, pure P, Al, Mg and Ti elements on the wetting/adhesion behavior of Sn-9Zn alloy to copper, as well as the associated oxidation and solidification morphology of this alloy were examined. The results show that harmful effect on the wettability can be found when adding Al and Ti elements, while the wettability can be improved slightly by adding Mg and Y elements. The adhesion of the alloy to copper can be decreased by Mg element. The RE and P are found to significantly improve the wettability. In addition, oxidation of the alloy can be increased by adding RE, while little effect on the oxidation behavior can be found by adding P element. As-solidified Sn-9Zn alloy has a rough surface with protrusions and cavities shaped by coarse needle-like crystallites, while the Sn-37Pb sample has a rather smooth surface, which indicates the different solidification behavior of Sn-9Zn alloy and the Sn-37Pb one. The additions of the different elements investigated in this study do not alter Sn-9Zn's as-solidified morphology.

  19. Geometrical thermodynamics analysis of the change in the Gibbs energy during the nonequilibrium solidification of eutectic alloys

    Science.gov (United States)

    Aleksandrov, V. D.; Sobolev, A. Yu.; Sobol', O. V.; Frolova, S. A.; Shchebetovskaya, N. V.

    2015-09-01

    Geometrical thermodynamics is used to analyze the possible dependences of the Gibbs energy on temperature and component concentration in the two-phase region during nonequilibrium solidification of eutectic alloys.

  20. Roles of Alloy Composition and Grain Refinement on Hot Tearing Susceptibility of 7××× Aluminum Alloys

    Science.gov (United States)

    Bai, Q. L.; Li, Y.; Li, H. X.; Du, Q.; Zhang, J. S.; Zhuang, L. Z.

    2016-08-01

    During the production of high-strength 7××× aluminum alloys, hot tearing has set up serious obstacles for attaining a sound billet/slab. In this research, some typical 7××× alloys were studied using constrained rod casting together with the measurement of thermal contraction and load development in the freezing range, aiming at investigating their hot tearing susceptibility. The results showed that the hot tearing susceptibility of an alloy depends not only on the thermal contraction in freezing range, which can decide the accumulated thermal strain during solidification, but also on the amount of nonequilibrium eutectics, which can effectively accommodate the thermally induced deformation. Our investigations reveal that Zn content has very profound effect on hot tearing susceptibility. The Zn/Mg ratio of the alloys also plays a remarkable role though it is not as pronounced as Zn content. The effect of Zn/Mg ratio is mainly associated with the amount of nonequilibrium eutectics. Grain refinement will considerably reduce the hot tearing susceptibility. However, excessive addition of grain refiner may promote hot tearing susceptibility of semi-solid alloy due to deteriorated permeability which is very likely to be caused by the heavy grain refinement and the formation of more intermetallic phases.

  1. STABILITY OF THE FAST-QUENCHED ALUMINUM ALLOYS MICROSTRUCTURE

    OpenAIRE

    A. S. Kalinichenko; V. A. Kalinichenko; V. S. Niss; S. V. Grigoryev

    2015-01-01

    The conducted researches of continuous stability of microstructures of the fast-quenched tapes from alloys of aluminum and chrome showed that the natural aging accompanied by discharge of stable phases is observed in copper-bearing alloys. There are no changes in microstructure in the chrome-bearing fast-chilled tapes that confirms their high temporary stability.

  2. Age hardening in beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    Three different alloys of beryllium-aluminum-silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight percent, Be-47.5Al-2.5Ag, Be-47Al-3Ag, and Be-46Al-4Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which separates from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatic pressing. Samples of hot isostatically pressed material were solution treated at 550 C for 1 h, followed by a water quench. Aging temperatures were 150, 175, 200, and 225 C for times ranging from half an hour to 65 h. Results indicate that peak hardness was reached in 36--40 h at 175 C and 12--16 h at 200 C aging temperature, relatively independent of alloy composition

  3. A Metric for the Quantification of Macrosegregation During Alloy Solidification

    Science.gov (United States)

    Fezi, Kyle; Plotkowski, Alex; Krane, Matthew J. M.

    2016-06-01

    A metric for quantifying the degree of solidification macrosegregation is proposed that statistically fits compositional data from experiments and simulations to a three-parameter Weibull distribution. The method for fitting such a distribution is described and examples are presented. The new metrics are compared to existing macrosegregation measures and the Weibull distribution is shown to be the best fit to data. The fitted three-parameter Weibull distribution is generally found to have better agreement with the composition data than a Gaussian distribution, upon which the macrosegregation number is based, because the Weibull better accounts for asymmetry in the dataset. Trends in macrosegregation results are identified using the new metrics, specifically the normalized Weibull deviation, and compared to the trends identified by the macrosegregation number. A grid dependence study is performed using both metrics as tests for convergence. The utility of the Weibull distribution is demonstrated by comparing composition data with different degrees of asymmetry due to different solidification cooling rates. The difference between the values of the two metrics is a measure of the asymmetry in the compositional distribution.

  4. Evolution of icosahedral clusters during the rapid solidification of liquid TiAl alloy

    International Nuclear Information System (INIS)

    The evolution characteristics of icosahedral clusters during the rapid solidification of TiAl alloy under different cooling rates are investigated based on molecular dynamics simulations. The short-range order structural properties of liquid and amorphous TiAl alloy are analyzed by several structural characterization methods. It is found that the cooling rate plays a key role during the evolution of icosahedral clusters and has significant effect on the glass transition temperature. Simultaneously, the medium-range order structural evolutions are described in detail by quantitative method and visualization technology during the rapid solidification. The results reveal that the medium-range order icosahedral clusters have good structural stability and configural continuity during the rapid cooling process. Furthermore, the icosahedral structures have significant improvements with decreasing cooling rate. The structures block the crystal nucleation and improve the glass forming ability of supercooled liquid.

  5. Solidification characteristics of Pb-Sb hypereutectic alloy within ultrasonic field

    Institute of Scientific and Technical Information of China (English)

    ZHAI Wei; HONG ZhenYu; XIE WenJun; WEI BingBo

    2007-01-01

    The solidification of Pb-16 %Sb hypereutectic alloy is investigated within ultrasonic field with a frequency of 15 kHz. It is found that the ultrasonic field promotes crystal nucleation and terminates the further bulk undercooling of the alloy melt. Theoretical analysis shows that the cavitation effect and the forced bulk vibration are the main factors that reduce the undercooling level. With the increase of ultrasound intensity, the primary (Sb) phase experiences a growth mode transition from faceted to non-faceted branched growth, and the macrosegregation of primary (Sb) phase is gradually suppressed. In addition, the microstructures of Pb-Sb eutectic exhibit a conspicuous coarsening with increasing ultrasound intensity, and a structural transition of "lamellar eutectic-anomalous eutectic"occurs when ultrasound intensity rises up to 1.6 W/cm2. The ultrasonic field also changes the solute distribution adjacent to the solidification front, which lowers the Pb contents in primary (Sb) phase.

  6. Estimation of the thickness of boundary layer in a broken line model of binary alloy solidification

    OpenAIRE

    D. Słota

    2010-01-01

    The solution of the inverse problem involving the designation of the thickness of boundary layer in a broken line model of binary alloysolidification for known temperature measurements at a selected point of the cast is presented. In the discussed model the temperaturedistribution is described by means of the Stefan problem with varying in time temperature corresponding to the beginning of solidification,depending on the concentration of the alloy component; whereas to describe the concentrat...

  7. Rheological behavior of Al-Mg-Si-Cu alloys in the mushy state obtained by partial remelting and partial solidification at high cooling rate

    Science.gov (United States)

    Fabrègue, D.; Deschamps, A.; Suéry, M.; Poole, W. J.

    2006-05-01

    This work investigates the mechanical behavior of two aluminum alloys in the mushy state, the alloy AA6056 and an alloy based on mixing AA6056 and AA4047. These alloys have been studied to give insight into the susceptibility to hot tearing, which occurs during laser welding of AA6056 with 4047 filler wire. Two types of isothermal tensile tests have been conducted: (1) tests during partial remelting and (2) tests after partial solidification at a high cooling rate. Results show that the maximum tensile stress increases with increasing solid volume fraction. Both materials exhibit visco-plastic behavior for solid fractions in the range 0.9 to 0.99, except for a critical solid fraction of 0.97, where the semisolid material also shows minimum ductility. The stress levels observed for the remelting experiments are larger than those found for partial solidification experiments at the same solid fraction due to the influence of the microstructure. The influence of temperature and strain rate on the maximum stress is described by using a constitutive law that takes into account the fraction of grain boundaries wetted by the liquid.

  8. Macrosegregation in Al-7Si alloy caused by abrupt cross-section change during directional solidification

    Science.gov (United States)

    Ghods, M.; Johnson, L.; Lauer, M.; Grugel, R. N.; Tewari, S. N.; Poirier, D. R.

    2016-09-01

    Hypoeutectic Al-7 wt .% Si alloys were directionally solidified vertically downward in cylindrical molds that incorporated an abrupt cross-section decrease (9.5 mm to 3.2 mm diameter) which, after 5 cm, reverted back to 9.5 mm diameter in a Bridgman furnace; two constant growth speeds and thermal gradients were investigated. Thermosolutal convection and cross-section-change-induced shrinkage flow effects on macrosegregation were investigated. Dendrite clustering and extensive radial macrosegregation was seen, particularly in the larger cross-sections, before contraction and after expansion, this more evident at the lower growth speed. This alloy shows positive longitudinal macrosegregation near cross-section decrease followed by negative macrosegregation right after it; the extent of macrosegregation, however, decreases with increasing growth speed. Primary dendrite steepling intensified as solidification proceeded into the narrower section and negative longitudinal macrosegregation was seen on the re-entrant shelves at expansion. A two-dimensional model accounting for both shrinkage and thermo-solutal convection was used to simulate solidification and the resulting mushy-zone steepling and macrosegregation. The experimentally observed longitudinal and radial macrosegregation associated with the cross-section changes during directional solidification of an Al-7Si alloy is well captured by the numerical simulations.

  9. Gating system optimization of low pressure casting A356 aluminum alloy intake manifold based on numerical simulation

    Directory of Open Access Journals (Sweden)

    Jiang Wenming

    2014-03-01

    Full Text Available To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on filling and solidification processes of the casting was carried out using the ProCAST software. The gating system of the casting is optimized according to the simulation results. Results show that when the gating system consists of only one sprue, the filling of the molten metal is not stable; and the casting does not follow the sequence solidification, and many shrinkage porosities are observed through the casting. After the gating system is improved by adding one runner and two in-gates, the filling time is prolonged from 4.0 s to 4.5 s, the filling of molten metal becomes stable, but this casting does not follow the sequence solidification either. Some shrinkage porosity is also observed in the hot spots of the casting. When the gating system was further improved by adding risers and chill to the hot spots of the casting, the shrinkage porosity defects were eliminated completely. Finally, by using the optimized gating system the A356 aluminum alloy intake manifold casting with integrated shape and smooth surface as well as dense microstructure was successfully produced.

  10. Segregation effects and phase developments during solidification of alloy 625

    DEFF Research Database (Denmark)

    Højerslev, Christian; Tiedje, Niels Skat; Hald, John

    2006-01-01

    material contained gamma-phase, Laves phase and, if carbon was dissolved in the liquid, niobium rich carbides formed. Molybdenum and niobium showed strong tendencies to segregate. Their segregation was balanced by inverse segregation of nickel and iron. The chromium concentration remained almost constant...... in gamma in the entire matrix material. Addition of carbon did not cause detectable alterations of the material that experienced planar front solidification. However, it promoted the formation of niobium rich carbides in the material that solidified eutectic-like. Thus, this material differed from...... that of the pure sample in constitution, and consequently in gamma-phase composition. Niobium rich carbides formed prior to Laves phase; in carbon rich volumes only the carbides form. As compared to the pure sample, the sample enriched in iron had decreased global minimal solute concentration in the...

  11. Influence of hydrogen content on the behavior of grain refinement in hypereutectic aluminum-silicon alloy

    Institute of Scientific and Technical Information of China (English)

    Lina Hu; Xiufang Bian; Youfeng Duan

    2004-01-01

    Dissolved hydrogen is harmful to mechanical properties of refined hypereutectic aluminum-silicon alloys. In the present work, by using a stepped-form mold and the hydrogen-detecting instrument HYSCAN Ⅱ, the relationship between the initial hydrogen content in the melt and the refinement effect on the casting of hypereutectic aluminum-silicon alloy was investigated. The experimental results show that the cooling rate, the hydrogen content and the grain refinement effect are three interactive factors. When the hydrogen content is above 0.20 mL/100 g and the cooling rate is lower than that in 50 mm-thick step, hydrogen dissolved in the alloy melt influences the grain refinement effect. With increasing the cooling rate, the critical hydrogen content increases too. It is expected that much hydrogen in the melt make the net interfacial energy larger than or equal to zero, resulting in the shielding of the particles AlP during solidification and that the critical gas content is closely related to the critical radius of embryo bubbles.

  12. Thermoelectrical power analysis of precipitation in 6013 aluminum alloy

    International Nuclear Information System (INIS)

    The 6013 aluminum alloy was first developed for application in the aircraft industry and, more recently, as a replacement option for the use of the 6061 alloy in the automotive industry. The present work describes the evolution of the process of formation and dissolution of different kinds of precipitates in 6013 aluminum alloy, subjected to different conditions of heat treatment, using for this purpose measurements of thermoelectrical power, Vickers microhardness and differential scanning calorimeter (DSC). Although in the last years many works have been published on the use of thermoelectrical power (TEP) measurements for the analysis of precipitation process in traditional alloys such as 6061, there is still little information related to 6013 alloy. The results obtained are compared with a previous characterization work on the same alloy using transmission electron microscopy. It was observed that TEP measurements are very sensitive to precipitation phenomena in this alloy, and it has been found that there is an inverse relation between TEP and Vickers microhardness values, which allowed proposing a precipitation sequence for 6013 aluminum alloy

  13. Effect of iron-intermetallics and porosity on tensile and impact properties of aluminum-silicon-copper and aluminum-silicon-magnesium cast alloys

    Science.gov (United States)

    Ma, Zheyuan

    Aluminum-silicon (Al-Si) alloys are an important class of materials that constitute the majority of aluminum cast parts produced, due to their superior properties and excellent casting characteristics. Within this family of alloys, Al-Si-Cu and Al-Si-Mg cast alloys are frequently employed in automotive applications. The commercially popular 319 and 356 alloys, representing these two alloy systems, were selected for study in the present work, with the aim of investigating the effect of iron intermetallics and porosity on the alloy performance. This was carried out through a study of the tensile and impact properties, these being two of the important mechanical properties used in design calculations. Iron, through the precipitation of second phase intermetallic constituents, in particular the platelike beta-Al5FeSi phase, is harmful to the alloy properties. Likewise, gas- or shrinkage porosity in castings is also detrimental to the mechanical properties. By determining the optimum alloying, melt processing and solidification parameters (viz., Fe content, Sr modification and cooling rate) required to minimize the harmful effects of porosity and iron intermetallics, and studying their role on the fracture behavior, the fracture mechanism in the alloys could be determined. Castings were prepared from both industrial and experimental 319.2, B319.2 and A356.2 alloy melts, containing Fe levels of 0.2--1.0 wt%. Sr-modified (˜200 ppm) melts were also prepared for each alloy Fe level. The end-chilled refractory mold used provided directional solidification and a range of cooling rates (or dendrite arm spacings, DAS) within the same casting. Tensile and impact test samples machined from specimen blanks sectioned from the castings at various heights above the chill end provided DASs of 23--85mum. All samples were T6-heat-treated before testing. Tests were carried out employing Instron Universal and Instrumented Charpy testing machines. Optical microscopy, image analysis, SEM

  14. China’s Aluminum Alloy Die Castings Industry has Promising Prospects

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Engine aluminum alloy engine block die casting experienced rapid development in recent years. Domestic enterprises introduced large die casting machine automatic production lines, and developed large aluminum alloy die cast-

  15. Low activation R-tokamak with aluminum alloy

    International Nuclear Information System (INIS)

    An aluminum alloy system is considered as an alternative of the first phase design of the R-tokamak. The 1-D calculation showed that the radiation level outside the vacuum vessel could be reduced by a factor of 30 about half a month after a D-T shot, when the aluminum alloy system is adopted instead of a stainless steel system. The aluminum system has weak mechanical strength, is highly conductive, and shows overaging effect at a certain low temperature. Accordingly, it is necessary to overcome these points. The highly conductive aluminum case leads to considerable increase in power consumption. Various problems on the toroidal coils, the vacuum system, and the limiter were studied. The optimization of the device parameters was investigated. (Kato, T.)

  16. Characterization of 2024-T3: An aerospace aluminum alloy

    International Nuclear Information System (INIS)

    The 2024-T3 aerospace aluminum alloy, reported in this investigation, was acquired from a local aerospace industry: Royal Malaysian Air Force (RMAF). The heat treatable 2024-T3 aluminum alloy has been characterized by use of modern metallographic and material characterization techniques (e.g. EPMA, SEM). The microstructural characterization of the metallographic specimen involved use of an optical microscope linked with a computerized imaging system using MSQ software. The use of EPMA and electron microprobe elemental maps enabled us to detect three types of inclusions: Al-Cu, Al-Cu-Fe-Mn, and Al-Cu-Fe-Si-Mn enriched regions. In particular, the presence of Al2CuMg (S-phase) and the CuAl2 (θ') phases indicated precipitation strengthening in the aluminum alloy

  17. Experimental study on activating welding for aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Huang Yong; Fan Ding

    2005-01-01

    TIG welding and EB welding for aluminum alloy 3003 were carried out to study the effects of activating flux on weld penetration of activating welding for aluminum alloys. SiO2 was used as the activating flux. It is found that, SiO2 can increase the weld penetration and decrease the weld width of FBTIG when the flux gap is small. For A-TIG welding and EB welding with focused mode, the weld penetrations and the weld widths increase simultaneously. SiO2 has little effect on the weld penetration and weld width of EB welding with defocused mode. It is believed that, change of surface tension temperature gradient is not the main mechanism of SiO2 improving weld penetration of activating welding for aluminum alloys.

  18. Comments on process of duplex coatings on aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Samir H.A.; QIAN Han-cheng(钱翰城); XIA Bo-cai(夏伯才); WU Shi-ming(吴仕明)

    2004-01-01

    Despite the great achievements made in improvement of wear resistance properties of aluminum alloys,their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired combination of surface properties. These problems can be solved through the duplex coatings. The aim of the present study is to overview the research advances on processes of duplex coatings on aluminum alloys combined with micro plasma oxidation process and with other modern processes such as physical vapour deposition and plasma assisted chemical vapour deposition and also to evaluate the performance of micro plasma oxidation coatings in improving the load-bearing, friction and wear resistance properties of aluminum alloys in comparison with other coatings. Wherein, a more detailed presentation of the processes and their performances and disadvantages are given as well.

  19. Superplasticity in powder metallurgy aluminum alloys and composites

    International Nuclear Information System (INIS)

    Superplasticity in powder metallurgy Al alloys and composites has been reviewed through a detailed analysis. The stress-strain curves can be put into 4 categories: classical well-behaved type, continuous strain hardening type, continuous strain softening type and complex type. The origin of these different types of is discussed. The microstructural features of the processed material and the role of strain have been reviewed. The role of increasing misorientation of low angle boundaries to high angle boundaries by lattice dislocation absorption is examined. Threshold stresses have been determined and analyzed. The parametric dependencies for superplastic flow in modified conventional aluminum alloys, mechanically alloyed alloys and Al alloy matrix composites is determined to elucidate the superplastic mechanism at high strain rates. The role of incipient melting has been analyzed. A stress exponent of 2, an activation energy equal to that for grain boundary diffusion and a grain size dependence of 2 generally describes superplastic flow in modified conventional Al alloys and mechanically alloyed alloys. The present results agree well with the predictions of grain boundary sliding models. This suggests that the mechanism of high strain rate superplasticity in the above-mentioned alloys is similar to conventional superplasticity. The shift of optimum superplastic strain rates to higher values is a consequence of microstructural refinement. The parametric dependencies for superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of superplasticity in aluminum alloy matrix composites, however, is different. A true activation energy of 313 kJ/mol best describes the composites having SiC reinforcements. The role of shape of the reinforcement (particle or whisker) and processing history is addressed. The analysis suggests that the mechanism for superplasticity in composites is interface diffusion controlled grain boundary sliding

  20. Electrorefining of aluminum alloy in ionic liquids at low temperatures

    OpenAIRE

    Kamavaram V.; Mantha D.; Reddy R.G.

    2003-01-01

    The electrorefining of aluminum alloy (A360) in ionic liquids at low temperatures has been investigated. The ionic liquid electrolyte was prepared by mixing anhydrous AlCl3 and 1-Butyl-3- methylimidazolium chloride (BMIC) in appropriate proportions. The effect of the cell voltage temperature, and the composition of the electrolyte on the electrorefining process has been studied. The characterization of the deposited aluminum was performed using scanning electron microscopy (SEM) and X-ray dif...

  1. Phase-field modeling of coring during solidification of Au–Ni alloy using quaternions and CALPHAD input

    International Nuclear Information System (INIS)

    A numerical method for the simulation of microstructure evolution during the solidification of an alloy is presented. The approach is based on a phase-field model including a phase variable, an orientation variable given by a quaternion, the alloy composition and a uniform temperature field. Energies and diffusion coefficients used in the model rely on thermodynamic and kinetic databases in the framework of the CALPHAD methodology. The numerical approach is based on a finite volume discretization and an implicit time-stepping algorithm. Numerical results for solidification and accompanying coring effect in a Au–Ni alloy are used to illustrate the methodology

  2. Improved thermal treatment of aluminum alloy 7075

    Science.gov (United States)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  3. A comparison of acoustic levitation with microgravity processing for containerless solidification of ternary Al-Cu-Sn alloy

    Science.gov (United States)

    Yan, N.; Hong, Z. Y.; Geng, D. L.; Wei, B.

    2015-07-01

    The containerless rapid solidification of liquid ternary Al-5 %Cu-65 %Sn immiscible alloy was accomplished at both ultrasonic levitation and free fall conditions. A maximum undercooling of 185 K (0.22 T L) was obtained for the ultrasonically levitated alloy melt at a cooling rate of about 122 K s-1. Meanwhile, the cooling rate of alloy droplets in drop tube varied from 102 to 104 K s-1. The macrosegregation was effectively suppressed through the complex melt flow under ultrasonic levitation condition. In contrast, macrosegregation became conspicuous and core-shell structures with different layers were formed during free fall. The microstructure formation mechanisms during rapid solidification at containerless states were investigated in comparison with the conventional static solidification process. It was found that the liquid phase separation and structural growth kinetics may be modulated by controlling both alloy undercooling and cooling rate.

  4. Bridgman Solidification of Concentrated GaInSb Alloys with Variable Growth Rate

    International Nuclear Information System (INIS)

    Experimental works and numerical simulations on concentrated Ga1-xInxSb alloys directional solidification at high crucible pulling rates, show a damping solutal effect on the thermally driven convection which leads to a significant increase of the chemical heterogeneity of the sample and of the solid-liquid interface curvature. Analytical calculations which give a quantitative description of the solutal effect, show that the melt convection damping can be avoided if low pulling rates of the crucible are used for the growth process. A Bridgman growth method, which uses a variable pulling rate in order to reduce the damping solutal effect and to improve the axial chemical homogeneity of the sample, is numerically investigated. The growth process can be started at high pulling rates which are reduced progressively during the solidification. From the numerical modeling, it is found that the axial and radial variations of solute concentration as well as the interface curvature are maintained at lower values when variables pulling rates are used for Bridgman solidification of high doped alloys

  5. Pitting behavior of 2024 aluminum alloy in nitrate solutions

    International Nuclear Information System (INIS)

    Pitting of 2024 aluminum alloy was investigated in chloride-containing nitrate solutions. Potentiostatic and potentiokinetic experiments followed by examination of the sample surface were performed in order to relate the pitting behavior of the alloy to its microstructure. The SEM examination showed that copper-rich particles were preferential sites for pitting. These particles started dissolving during the polarization in nitrate solutions due to the agressivity of nitrate ions toward copper. In the presence of chloride ions, these particles were completely dissolved. Nitrate ions on the other hand appeared to have a very strong inhibitory effect toward pitting in the aluminum matrix. (author)

  6. Forming analysis and application for aluminum-alloy material

    Institute of Scientific and Technical Information of China (English)

    Wei Yuansheng

    2012-01-01

    The increase in car ownership brought about by energy shortages, and environmental crises became more acute. The most effective way to achieve energy saving and emission reduction of car is to improve engine efficiency. In addition to that, lightweight body is the key. Aluminum, magnesium alloy as significant materials of lightweight, and the application amount in the car body is a significant upward trend. However, there is high cost of material, with im- mature applied technology and a series of bottleneck problems. All of them affect general application of lightweight mate- rials. This paper focuses on forming process issues for aluminum, magnesium alloy and the solutions to achieve.

  7. Effect of pressure on heat transfer coefficient at the metal/mold interface of A356 aluminum alloy

    DEFF Research Database (Denmark)

    Fardi Ilkhchy, A.; Jabbari, Masoud; Davami, P.

    2012-01-01

    The aim of this paper is to correlate interfacial heat transfer coefficient (IHTC) to applied external pressure, in which IHTC at the interface between A356 aluminum alloy and metallic mold during the solidification of casting under different pressures were obtained using the inverse heat...... presented for correlation between external pressure and heat transfer coefficient. Acceptable agreement with data in literature shows the accuracy of the proposed formula....... conduction problem (IHCP) method. The method covers the expedient of comparing theoretical and experimental thermal histories. Temperature profiles obtained from thermocouples were used in a finite difference heat flow program to estimate the transient heat transfer coefficients. The new simple formula was...

  8. Thermodynamics of Titanium-Aluminum-Oxygen Alloys Studied

    Science.gov (United States)

    Copland, Evan H.; Jacobson, Nathan S.

    2001-01-01

    Titanium-aluminum alloys are promising intermediate-temperature alloys for possible compressor applications in gas-turbine engines. These materials are based on the a2-Ti3Al + g-TiAl phases. The major issue with these materials is high oxygen solubility in a2-Ti3Al, and oxidation of unsaturated alloys generally leads to mixed non-protective TiO2+Al2O3 scales. From phase diagram studies, oxygen saturated a2-Ti3Al(O) is in equilibrium with Al2O3; however, oxygen dissolution has a detrimental effect on mechanical properties and cannot be accepted. To better understand the effect of oxygen dissolution, we examined the thermodynamics of titanium-aluminum-oxygen alloys.

  9. Preparation of semi-solid slurry containing fine and globular particles for wrought aluminum alloy 2024

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouring with shearing field(LSPSF). The appreciate combination of pouring temperature and rotation speed of barrel, can give rise to a transition of the growth morphology of primary α(Al) from coarse-dendritic to coarse-particle-like and further to fine-globular. The combined effects of both localized rapid cooling and vigorous mixing during the initial stage of solidification can enhance wall nucleation and nuclei survival, which leads to the formation of fine-globular primary α(Al). By using semi-solid slurry prepared by LSPSF, direct squeeze cast cup-shaped component with improved mechanical properties such as yield strength of 198MPa, ultimate tensile strength of 306 MPa and elongation of 10.4%, can be obtained.

  10. Aluminum Alloy Semisolid Strip Casting Using an Unequal Diameter Twin Roll Caster

    Directory of Open Access Journals (Sweden)

    T. Haga

    2005-12-01

    Full Text Available Purpose: A Purpose of the present study was to break through the disadvantage of the twin roll caster for aluminum alloy. They were slow casting speed and limitation of alloy. For example, the casting speed was slower than 5 m/min, and casting of hypereutectic Al-Si alloy was difficult. In order to break through the disadvantages, semisolid casting using an unequal diameter twin roll caster was tested its ability.Design/methodology/approach: The specification of the unequal diameter twin roll caster is as below. The diameter of the upper roll was 250 mm, and that of the lower roll was 1000 mm. The width of the roll was 100 mm. The semisolid slurry was made by a cooling slope.Findings: The microstructure of the strip became very fine. Especially, primary and eutectic Si became very fine. This was the effect of rapid solidification. As the result, the ductility of Al-16%Si was improved.Research limitations/implications: 6111 aluminum alloy strip was cast at speeds of 5, 10 and 20 m/min. This caster could cast the strip at the speeds higher than the conventional twin roll caster. Start of casting was very easy. The hypereutectic Al-16%Si alloy, which has wide freezing zone, could be cast in to the strip by the unequal diameter twin roll caster. This was the effect of the cooling of the strip on the lower roll.Originality/value: The roll cast Al-16mass%Si strip had good ductility, and could be cold rolled. Annealed 0.5 mm thick Al-16mass%Si could be bent at radius of 0.75mm.

  11. Rapid solidification and phase stability evaluation of Ti-Si-B alloys

    International Nuclear Information System (INIS)

    Research highlights: → Rapid solidification of Ti-rich Ti-Si-B alloys promoted significant refinement of the microstructures. → Amorphous and amorphous with embedded nanocrystals have been observed after rapid solidification from specific alloy compositions. → The values of the crystallization temperature (Tx) of the alloys were in the 509-647 deg. C temperature range. → After Differential Scanning Calorimetry and High Temperature X-ray diffraction with synchrotron radiation, the alloys showed crystalline and basically formed by two or three of the following phases: αTi, Ti6Si2B; Ti5Si3; Ti3Si and TiB. → It has been shown the stability of the Ti3Si and Ti6Si2B phases at 700 deg. C and the proposition of an isothermal section at this temperature. - Abstract: Ti-rich Ti-Si-B alloys can be considered for structural applications at high temperatures (max. 700 deg. C), however, phase equilibria data is reported only for T = 1250 deg. C. Thus, in this work the phase stability of this system has been evaluated at 700 deg. C. In order to attain equilibrium conditions in shorter time, rapid solidified samples have been prepared and carefully characterized. The microstructural characterization of the produced materials were based on X-ray diffraction (XRD), scanning electron microscopy (SEM-BSE), high resolution transmission electron microscopy (HRTEM), High Temperature X-ray diffraction with Synchrotron radiation (XRDSR) and Differential Scanning Calorimetry (DSC). Amorphous and amorphous with embedded nanocrystals have been observed after rapid solidification from specific alloy compositions. The values of the crystallization temperature (Tx) of the alloys were in the 509-647 deg. C temperature range. After Differential Scanning Calorimetry and High Temperature X-ray Diffraction with Synchrotron radiation, the alloys showed crystalline and basically formed by two or three of the following phases: αTi, Ti6Si2B; Ti5Si3; Ti3Si and TiB. It has been shown the

  12. In situ observations of solidification processes in γ-TiAl alloys by synchrotron radiation

    International Nuclear Information System (INIS)

    In situ observations of phase transformations involving melts are performed using energy-dispersive diffraction of synchrotron X-rays on electromagnetically levitated γ-TiAl alloys containing Nb. The determined primary solidification modes, confirmed by microstructure analysis, delivered new reliable data about the boundary of the α(Ti) solidification domain, which differs in the various Ti-Al-Nb phase diagram descriptions. These data have been used for a reassessment of the thermodynamic database of the ternary Ti-Al-Nb system. The new description realistically reflects the experimental findings. Liquidus and solidus temperatures determined by the pyrometric method agree fairly well with the calculated values. Direct experimental information on the nature of the reactions along the univariant lines is provided.

  13. Modeling of solidification grain structure for Ti-45%Al alloy ingot by cellular automaton

    Institute of Scientific and Technical Information of China (English)

    WU Shi-ping; LIU Dong-rong; GUO Jing-jie; FU Heng-zhi

    2005-01-01

    A cellular automaton model for simulating grain structure formation during solidification processes of Ti45%Al(mole fraction) alloy ingot was developed, based on finite differential method for macroscopic modeling of heat transfer and a cellular automaton technique for microscopic modeling of nucleation, growth, solute redistribution and solute diffusion. The relation between the growth velocity of a dendrite tip and the local undercooling,which consists of constitutional, thermal, curvature and attachment kinetics undercooling is calculated according to the Kurz-Giovanola-Trivedi model. The effect of solidification contraction is taken into consideration. The influence of process variables upon the resultant grain structures was investigated. Special moving allocation technique was designed to minimize the computation time and memory size associated with a large number of cells. The predicted grain structures are in good agreement with the experimental results.

  14. Separating Effect of a Novel Combined Magnetic Field on Inclusions in Molten Aluminum Alloy

    Science.gov (United States)

    He, Yanjie; Li, Qiulin; Liu, Wei

    2012-10-01

    The feasibility and effectiveness of a novel combined magnetic field (CMF) on the removal of inclusions with a density smaller than the surrounding melt were investigated. The experiment of the separating effect of CMF was conducted on a laboratory-scale apparatus by the simultaneous application of a rotating magnetic field (RMF) and a downward traveling magnetic field (TMF). Primary silicon particles precipitating from the solidification process of Al-Si-Cu alloy were regarded as the inclusions in a molten aluminum alloy. It was found that a CMF consisting of both a RMF and a downward TMF was able to separate silicon particles from the molten Al-Si-Cu alloy by making these particles migrate vertically toward the upper part of the samples. Compared with downward TMF or RMF, CMF improved the separating effectiveness substantially. It was proposed that this type of CMF was approved to be highly effective at eliminating the inclusions with a density smaller than the surrounding molten alloy. A tentative mechanism for the high separating effect of CMF was discussed.

  15. Experimental investigation of the natural and forced convection on solidification of Sn-3wt. %Pb alloy using a benchmark experiment

    OpenAIRE

    Hachani, Lakhdar; Boussaa, Redouane; Saadi, Bachir; X. D. Wang; Zaidat, Kader; Belgacem Bouzida, Aissaa; Henry, D.; Henry, Dominique; Botton, Val‚éry; Ben Hadid, H.; Fautrelle, Yves

    2012-01-01

    International audience We deal with the development of a solidification benchmark experiment in order to investigate the structure formation as well as solute macro-mesosegregation, by means of a well-controlled solidification experiment. The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb alloy, by using two lateral heat exchangers which allow extraction of the heat flux from one or two vertical sides of the sample. The domain is a quasi two dimensional parallepipedic...

  16. Effects of electromagnetic stirring on microstructures of solidified aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    时海芳; 张伟强

    2003-01-01

    Al-20%Cu, Al-33%Cu and Al-7%Si alloys were solidified with electromagnetic stirring(EMS). The fluid flow induced by electromagnetic stirring leads to the increases of the lamellar spacing of Al-CuAl2 and Al-Si eutectics and the secondary dendritic arm spacing. Rod-like eutectic structure plus pro-eutectic α(Al) are observed in Al-Cu eutectic alloy when the agitating voltage is increased over 130 V, and in the hypoeutectic alloys, globular grains of proeutectic α(Al) grains may form when the magnetic field is strong enough. The Si flakes in the Al-Si eutectic are also coarsened by applying forced flow during solidification, which is always related to the depression of their branching in the growth by the forced convection.

  17. Segregation and evaporation behaviors of aluminum and calcium in silicon during solidification process induced by electron beam

    International Nuclear Information System (INIS)

    An experimental investigation into the removal of aluminum (Al) and calcium (Ca) from molten silicon by using electron beam melting was carried out. Based on the distributions of Al and Ca along the growth direction of the ingot under different solidification conditions, the influence of segregation and evaporation behaviors on the removal of such impurities with both high saturated vapor pressure and low segregation coefficients was investigated. The results showed that the distributions of impurities depend upon the interaction between segregation and evaporation, so that the removal efficiency can be further improved by adjusting the melting parameters. Compared with the traditional electron beam melting process, the energy consumption decreases by 20% during the whole melting and solidification process. It is considered to be a more effective way for the purification of silicon and the reduction of energy consumption by electron beam melting. (paper)

  18. Undercooling and rapid solidification of Nb-Si eutectic alloys studied by long drop tube

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-ren; DONG Shu-yong; WEI Bing-chen; LI Wei-huo

    2006-01-01

    Niobium-silicide alloys have great potential for high temperature turbine applications. The two-phase Nb/Nb5Si3 in situ composites exhibit a good balance in mechanical properties. Using the 52 m drop tube, the effect of undercooling and rapid solidification on the solidification process and micro-structural characterization of Nb-Si eutectic alloy was studied. The microstructures of the Nb-Si composites were investigated by optics microscope (OM), X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with X-ray energy dispersive spectrometry (EDS). Up to 480 K, deep undercooling of the Nb-Si eutectic samples was successfully obtained, which corresponds to 25% of the liquidus temperature. Contrasting to the conventional microstructure usually found in the Nb-Si eutectic alloy, the microstructure of the undercooled sample is divided into the fine and coarse regions. The most commonly observed microstructure is Nb+Nb5Si3, and the Nb3Si phase is not be found. The change of coarseness of microstructure is due to different cooling rates during and after recalescence. The large undercooling is sufficient to completely bypass the high temperature phase field.

  19. Binary Fe-Nd metastable phases in the solidification of Fe-Nd-B alloys

    International Nuclear Information System (INIS)

    It has been shown that a binary Fe-Nd metastable phase, A1, is responsible for coercivity of ≅ 5 k O e in Fe 80 Nd 5B as-cast alloys. It is rapidly transformed into Fe14 Nd2 B after a very short annealing at 600 deg C and it is also present in alloys of magnet composition. Thus it may account for the lower coercivity of as-sintered magnets. here we discuss how can this phase can be formed in the solidification of Fe-Nd-B magnets. The microstructure and thermal events of DTA samples of constant 60 at%Nd were used to construct a vertical section of the Fe-Nd-B ternary phase diagram. The solidification of alloys related to magnet compositions did not follow the path predicted by the known phase diagrams which leads to a ternary eutectic. Instead, they pass through a transition reaction, involving Fe4 Nd B4, liquid, Fe14 Nd2 B and Nd, which may reach the binary Fe-Nd eutectic, giving rise to different metastable phases, depending on the cooling rate: A1, A1 or fe17 Nd2. A new version of the liquidus projection of the Nd-rich corner of the ternary phase diagram is presented. (author)

  20. CO2 laser welding of aluminum alloys at high speeds up to 20 m/min

    Science.gov (United States)

    Takahashi, Kunimitsu; Kumagai, Mikio; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    CO2 laser welding of thin aluminum sheets was performed at welding speeds of up to 20 m/min to investigate the weldability, weld pool dynamics and mechanical properties of the weld bead of aluminum alloys. High-speed camera observation of weld areas showed that the thickness of the keyhole-front-face decreased to 100 μm under high-speed welding conditions and the weld pool became unstable. The focal length was optimized to increase the spot power density and thereby easily melt the aluminum sheets. Using a 76-mm focal length lens, which corresponds to 11 MW/cm2 power density, we obtained a keyhole mode weld bead with a depth of 1.3 mm at 20 m/min welding speed at 2 kW laser power. It was also possible to reduce the heat affected zone (HAZ) width to only 1.6 mm when the welding speed was 20 m/min. The HAZ width decreased as welding speed was increased. The tensile strength test of A6N01 weld beads showed that the fracture strength increased as the welding speed was increased up to 16 m/min, probably because the soft region of weld specimens was decreased. On the other hand, solidification cracks formed in the weld bead center at higher speeds, resulting in decreased strength.

  1. Lead induced intergranular fracture in aluminum alloy AA6262

    NARCIS (Netherlands)

    De Hosson, JTM

    2003-01-01

    The influence of lead on the fracture behavior of aluminum alloy AA6262 is investigated. Under certain conditions, the mode of fracture changes from transgranular microvoid coalescence to an intergranular mechanism. Three different intergranular fracture mechanisms are observed: liquid metal embritt

  2. Fracture behavior of low-density replicated aluminum alloy foams

    NARCIS (Netherlands)

    Amsterdam, E.; Goodall, R.; Mortensen, A.; Onck, P. R.; De Hosson, J. Th. M.

    2008-01-01

    Tensile tests have been performed on replicated aluminum alloy foams of relative density between 4.5% and 8%. During the test the electrical resistance was measured with a four-point set-up and the displacements along the gage section were measured using a digital image correlation (DIC) technique.

  3. Effects of high frequency current in welding aluminum alloy 6061

    Science.gov (United States)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  4. Testing of 2219-T87 aluminum alloy at 40K

    International Nuclear Information System (INIS)

    The tensile and fracture properties of heavy section (1.5 inches thick) 2219-T87 plate aluminum alloy at 40K were determined. Transverse and longitudinal crack growth parameters were measured. Tensile specimens were taken at L, T, and ST orientations and tensile data is tabulated. K/sub Ic/ tests results and fatigue-crack growth data are summarized

  5. Titanium-zirconium-phosphonate hybrid film on 6061 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Shuanghong WANG; Lei WANG; Changsheng LIU

    2011-01-01

    Three titanium-zirconium-phosphonate hybrid films were formed on AA6061 aluminum alloy by immersing in fluorotitanic acid and fluorozirconic acid based solution containing different phosphonic acids for protective coatings of aluminium alloy. The corrosion resistance of three hybrid films as the substitute for chromate film were evaluated and compared. The neutral salt spray test was explored,the immersion test was conducted and electrochemical test was also executed. The hybrid films exhibited well-pleasing corrosion resistance and adhesion to epoxy resin paints. It was found out that the hybrid films could efficiently be a substitute for chromate based primer over aluminium alloy.

  6. New all aluminum alloy ultrahigh vacuum system and fittings

    International Nuclear Information System (INIS)

    The Al-ICF ALFLAT FLANGE corresponds to the ordinary stainless steel Conflat flange. The Al-ICF ALFLAT FLANGE is made of special aluminum alloy 2219-T87 by forging. It has the highest strength at elevated high temperature among all aluminum alloys as well as superior weldability and stress corrosion cracking resistivity. CrN or TiC coating on the flange surface by ion plating. The CrN or TiC treatment on the surface gave nearly protection against sticking between the knife edge of the flange and the aluminum gasket and surface scratching. Sealing surface of the knife edge for the Helicoflex is finished to a smooth mirror surface by a diamond tool. (author)

  7. Estimation of the thickness of boundary layer in a broken line model of binary alloy solidification

    Directory of Open Access Journals (Sweden)

    D. Słota

    2010-10-01

    Full Text Available The solution of the inverse problem involving the designation of the thickness of boundary layer in a broken line model of binary alloysolidification for known temperature measurements at a selected point of the cast is presented. In the discussed model the temperaturedistribution is described by means of the Stefan problem with varying in time temperature corresponding to the beginning of solidification,depending on the concentration of the alloy component; whereas to describe the concentration, a broken line model was used.

  8. Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

    Science.gov (United States)

    Aghion, E; Jan, L; Meshi, L; Goldman, J

    2015-11-01

    Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons. PMID:25491147

  9. System for ultra high vacuum made of aluminum alloys

    International Nuclear Information System (INIS)

    We have developed the system for ultra high vacuum made of aluminum alloys for proton and electron synchrotron. This is the first system for ultra high vacuum in which bakable metal seal flange and small diametral bellows of aluminum alloys have been put to practical use. The system consists of the flange protected by a CrN thin film and made of 2219-T87 alloy, the chamber made of 6063-T6 alloy, the aluminum metal gasket of Helico Flex and the bellows made of 5052 alloy. As a result of experiments at the National Laboratory for High Energy Physics (KEK), it had been confirmed that this system shows the special qualities of ultra high vacuum operation, resistance to hard radiation and baking and cooling operations. Up to now, this system has been widely used for the beam lines of the booster synchrotron utilization facility, K1, K2, linac, PI 1 and EP2-B extension of the KEK proton synchrotron. We investigate that this system is applicable to nuclear energy utilization facility and general vacuum apparatus. (author)

  10. Cleavage crystallography of liquid metal embrittled aluminum alloys

    Science.gov (United States)

    Reynolds, A. P.; Stoner, G. E.

    1991-01-01

    The crystallography of liquid metal-induced transgranular cleavage in six aluminum alloys having a variety of microstructures has been determined via Laue X-ray back reflection. The cleavage crystallography was independent of alloy microstructure, and the cleavage plane was 100-plane oriented in all cases. It was further determined that the cleavage crystallography was not influenced by alloy texture. Examination of the fracture surface indicated that there was not a unique direction of crack propagation. In addition, the existence of 100-plane cleavage on alloy 2024 fracture surfaces was inferred by comparison of secondary cleavage crack intersection geometry on the 2024 surfaces with the geometry of secondary cleavage crack intersections on the test alloys.

  11. Fabrication of superhydrophobic nanostructured surface on aluminum alloy

    Science.gov (United States)

    Jafari, R.; Farzaneh, M.

    2011-01-01

    A superhydrophobic surface was prepared by consecutive immersion in boiling water and sputtering of polytetrafluoroethylene (PTFE or Teflon®) on the surface of an aluminum alloy substrate. Immersion in boiling water was used to create a micro-nanostructure on the alloy substrate. Then, the rough surface was coated with RF-sputtered Teflon film. The immersion time in boiling water plays an important role in surface morphology and water repellency of the deposited Teflon coating. Scanning electron microscopy images showed a "flower-like" structure in first few minutes of immersion. And as the immersion time lengthened, a "cornflake" structure appeared. FTIR analyses of Teflon-like coating deposited on water treated aluminum alloy surfaces showed fluorinated groups, which effectively reduce surface energy. The Teflon-like coating deposited on a rough surface achieved with five-minute immersion in boiling water provided a high static contact angle (˜164°) and low contact angle hysteresis (˜4°).

  12. Experimental research on solidification structure of alloy 800H by linear electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    Jiang En; Wang Engang; Deng Anyuan

    2014-01-01

    The solidification structures of al oy 800H fabricated with and without linear electromagnetic stirring (L-EMS) were investigated. The results show that the solidification structure of the alloy can be obviously affected by the forced convection in melt caused by L-EMS. The average size of equiaxed grains of the al oy with L-EMS decreases from 3.5 mm to 2.3 mm, and the ratio of equiaxed grain increases from 5% to 43%compared with that without L-EMS. The microstructure of the al oy without L-EMS is composed of fine equiaxed dendrites in the outermost layer and columnar dendrites in other areas, whereas that with L-EMS contains equiaxed dendrites, columnar dendrites and cross dendrites. In addition, the mechanism of dendrite fragment drift was proved by examining the composition change of the main al oying elements in the dendrite trunks at different solidification stage using an electron probe micro-analyzer (EPMA).

  13. Dendrite fragmentation in alloy solidification due to sidearm pinch-off.

    Science.gov (United States)

    Neumann-Heyme, H; Eckert, K; Beckermann, C

    2015-12-01

    Dendrite sidebranch detachment is an important fragmentation mechanism during the solidification of alloys. The detachment occurs at the junction between a sidearm and its parent stem. While this pinching process is driven by capillarity, the presence of solidification opposes the instability. Using a simple numerical model of a single sidearm, we are able to capture the essential dynamics of dendrite sidebranch development and the resulting morphological transitions. While shortly before pinch-off the neck itself obeys well-known universal scaling relations, the overall evolution of the sidearm shape sensitively depends on its initial geometry and the rate of solidification. It is found that pinch-off only occurs over limited ranges of geometrical parameters and cooling rates and is generally bounded by sidearm retraction and coalescence regimes. Simple scaling relations are identified that provide the bounds for the pinch-off regime. Pinching at the branching point is shown to be faster than the Rayleigh-Plateau instability of an infinitely long cylinder. PMID:26764615

  14. Project Explorer: Get Away Special #007. [alloy solidification, seed germination, crystal growth, and radio transmission of payload data

    Science.gov (United States)

    Henderson, A. J., Jr.

    1984-01-01

    Tentatively scheduled to fly on STS-17 (41G), this get away special aims to demonstrate amateur radio transmissions to global ground stations in the English language. Experiments No. 1, 2, and 3 use the micro-gravity of space flight to study the solidification of lead-antimony and aluminum-copper alloys, the germination of radish seeds, and the growth of potassium-tetracyanoplatinate hydrate crystals in an aqueous solution. Flight results are to be compared with Earth-based data. Experiment No. 4 (the Marshall Amateur Radio Club Experiment - MARCE) features radio transmissions and also provides timing for the start of all other experiments. A microprocessor obtains real-time data from all experiments as well as temperature and pressure measurements within the GAS canister. These data are to be transmitted on previously announced amateur radio frequencies after they are converted into the English language by a digitalker for general reception. The support structure for the G #007 experiments consists of two primary plates and four bumper assemblies.

  15. Numerical Simulation Microstructure Morphology Evolution and Solute Microsegregation of Al-Si-Cu Ternary Alloys during Solidification Process

    Science.gov (United States)

    Xie, Shuisheng; Huang, Guojie; Cheng, Lei; Fu, Yao; Li, Qiang

    2011-06-01

    A 2D microstructure and solute microsegregation model of Al-Si-Cu ternary alloys is presented by using cellular automaton(CA) method. In CA model, an improved algorithm was presented that abandoned the assumption of solid/liquid interface position and velocity so as to calculate the solid fraction in the solid/liquid interface unit. Then, using CA model, a dendrite of Al-Si-Cu ternary alloys is simulated. Finally, solidification microstructure and solute microsegregation are simulated, and the simulated results can reflect the microstructure and different solute microsegregation during solidification process.

  16. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  17. Microstructural and superplastic characteristics of friction stir processed aluminum alloys

    Science.gov (United States)

    Charit, Indrajit

    Friction stir processing (FSP) is an adapted version of friction stir welding (FSW), which was invented at The Welding Institute (TWI), 1991. It is a promising solid state processing tool for microstructural modification at localized scale. Dynamic recrystallization occurs during FSP resulting in fine grained microstructure. The main goal of this research was to establish microstructure/superplasticity relationships in FSP aluminum alloys. Different aluminum alloys (5083 Al, 2024 Al, and Al-8.9Zn-2.6Mg-0.09Sc) were friction stir processed for investigating the effect of alloy chemistry on resulting superplasticity. Tool rotation rate and traverse speeds were controlled as the prime FSP parameters to produce different microstructures. In another study, lap joints of 7475 Al plates were also studied to explore the possibility of developing FSW/superplastic forming route. Microstructures were evaluated using optical, scanning and transmission electron microscopy, orientation imaging microscopy and differential scanning calorimetry. Mechanical properties were evaluated using tensile testing. FSP 2024 Al (3.9 mum grain size) exhibited an optimum ductility of 525% at a strain rate of 10-2 s-1 and 430°C. Grain boundary sliding mechanism was found to be the dominant mode of deformation in this alloy. In 5083 Al alloy, it was found that changing the process parameters, grain sizes in the range of 3.5--8.5 mum grain size could be obtained. Material processed with colder processing parameters showed a decrease in ductility due to microstructural instability, and followed solute drag dislocation glide mechanism. On the other hand, materials processed with hotter parameter combinations showed mode of deformation related to grain boundary sliding mechanism. FSP of as-cast Al-Zn-Mg-Sc alloy resulted in ultrafine grains (0.68 mum) with attractive combination of high strain rate and low temperature superplasticity. This also demonstrated that superplastic microstructures could be

  18. Modified cellular automaton model for modeling of microstructure and microsegregation in solidification of ternary alloys

    Institute of Scientific and Technical Information of China (English)

    ZHU Ming-fang; CAO Wei-sheng; CHEN Shuang-lin; XIE Fan-you; HONG Chunpyo; CHANG Y. Austin

    2006-01-01

    A modified cellular automaton (MCA) model has been extended to the ternary alloy system by coupling thermodynamic and phase equilibrium calculation engine PanEngine. In the present model the dendrite growth is driven by the difference between the local equilibrium liquidus temperature and local actual temperature, incorporating the effect of curvature. The local equilibrium liquidus temperature is calculated with PanEngine according to the local liquid concentrations of two solutes, which are determined by numerically solving the species transport equation in the domain. Model validation was carried out through the comparison of the simulated values to the prediction of the Scheil model for solute profiles in the primary dendrites. The simulated data with zero solid diffusivity and limited liquid diffusivity were increasingly close to the Scheil profiles as the solidification rate decreased. The simulated microstructure and microsegregation in an Al-Cu-Mg ternary alloy were compared with those obtained experimentally.

  19. Crystal Growth of HgZnTe Alloy by Directional Solidification in Low Gravity Environment

    Science.gov (United States)

    Su, Ching-Hua; Sha, Yi-Gao; Lehoczky, S. L.; Szofran, F. R.; Gillies, D. C.; Scripa, R. N.; Cobb, S. D.; Wang, J. C.

    2002-01-01

    An Hg(0.84)Zn(0.16)Te alloy crystal was back-melted and partially re-solidified during the first United States Microgravity Laboratory mission in the Marshall Space Flight Center's Crystal Growth Furnace. The experiment was inadvertently terminated at about 30% of planned completion. Nonetheless, it was successfully demonstrated that a HgZnTe alloy ingot partially grown and quenched on the ground can be back-melted and re-grown in space under nearly steady-state growth conditions. An identical "ground-truth" experiment was performed following the mission and a comparison between the properties of the crystals is described. The results indicate the importance of residual microgravity acceleration (less than or approx. equal to 0.4 micro-grams) even in the sub-microgravity range for the slow solidification velocities and large density gradients.

  20. Modeling solute segregation during the solidification of γ-phase U-Mo alloys

    Science.gov (United States)

    Steiner, M. A.; Garlea, E.; Agnew, S. R.

    2016-06-01

    Using first principles calculations, it is demonstrated that solute segregation during U-Mo solidification can be modeled using the classic Brody-Fleming limited diffusion framework. The necessary supporting equations specific to the U-Mo alloy, along with careful verification of the assumptions underpinning the Brody-Fleming model are developed, allowing for concentration profile predictions as a function of alloy composition and cooling rate. The resulting model is compared to experimental solute concentration profiles, showing excellent agreement. Combined with complementary modeling of dendritic feature sizes, the solute segregation model can be used to predict the complete microstructural state of individual U-Mo volume elements based upon cooling rates, informing ideal processing routes.

  1. Effect of steady and time-harmonic magnetic fields on macrosegragation in alloy solidification

    Energy Technology Data Exchange (ETDEWEB)

    Incropera, F.P.; Prescott, P.J. [Purdue Univ., West Lafayette, IN (United States)

    1995-12-31

    Buoyancy-induced convection during the solidification of alloys can contribute significantly to the redistribution of alloy constituents, thereby creating large composition gradients in the final ingot. Termed macrosegregation, the condition diminishes the quality of the casting and, in the extreme, may require that the casting be remelted. The deleterious effects of buoyancy-driven flows may be suppressed through application of an external magnetic field, and in this study the effects of both steady and time-harmonic fields have been considered. For a steady magnetic field, extremely large field strengths would be required to effectively dampen convection patterns that contribute to macrosegregation. However, by reducing spatial variations in temperature and composition, turbulent mixing induced by a time-harmonic field reduces the number and severity of segregates in the final casting.

  2. DEFINITION OF THE CASTING MECHANISMS OF ALUMINUM-SILICON ALLOYS WITH SUPERFINE AND INVERTED MICROSTRUCTURE

    Directory of Open Access Journals (Sweden)

    V. Yu. Stetsenko

    2013-01-01

    Full Text Available The basic mechanisms of Al-Si alloysmodifying are determined. Fast solidification and inheritance modification are major in casting of alloys with a highly dispersed and inverted microstructure.

  3. Hydrogen interactions in aluminum-lithium alloys

    Science.gov (United States)

    Smith, S. W.; Scully, J. R.

    1991-01-01

    A program is described which seeks to develop an understanding of the effects of dissolved and trapped hydrogen on the mechanical properties of selected Al-Li-Cu-X alloys. A proposal is made to distinguish hydrogen (H2) induced EAC from aqueous dissolution controlled EAC, to correlate H2 induced EAC with mobile and trapped concentrations, and to identify significant trap sites and hydride phases (if any) through use of model alloys and phases. A literature review shows three experimental factors which have impeded progress in the area of H2 EAC for this class of alloys. These are as listed: (1) inter-subgranular fracture in Al-Li alloys when tested in the S-T orientation in air or vacuum make it difficult to readily detect H2 induced fracture based on straight forward changes in fractography; (2) the inherently low H2 diffusivity and solubility in Al alloys is further compounded by a native oxide which acts as a H2 permeation barrier; and (3) H2 effects are masked by dissolution assisted processes when mechanical testing is performed in aqueous solutions.

  4. Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.

    2016-07-01

    The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

  5. Solidification behavior of Sn-9Zn-xAg lead-free solder alloys

    International Nuclear Information System (INIS)

    Solidification behaviors of Sn-9Zn-xAg lead-free solder alloys, which vary with Ag content, are examined by using scanning electron microscopy, electron probe microanalysis, X-ray analysis, computer aided-cooling curve analysis and differential scanning calorimetry. The backscattered images and X-ray diffraction patterns indicate that with the addition of two silver intermetallic compounds; γ-Ag5Zn8 and ε-AgZn3, form in the expense of zinc phase. The solid fraction versus temperature relationship and microstructure analysis show that Sn-Zn eutectic structures appear following the formation of primary tin. It is concluded in this study that the complicated solidification process of Sn-9Zn-xAg alloys can be described as L (liquid) → L + γ-Ag5Zn8→ L + γ-Ag5Zn8 + ε-AgZn3→ L + γ-Ag5Zn8 + ε-AgZn3 + β-Sn → γ-Ag5Zn8 + ε-AgZn3 + β-Sn + eutectic (Sn + Zn)

  6. Solidification behavior of Sn-9Zn-xAg lead-free solder alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Y.-L. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China); Hwang, W.-S. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan, Taiwan (China) and Metal Industries Research and Development Centre, Kaohsiung, Taiwan (China)]. E-mail: wshwang@mail.ncku.edu.tw

    2005-12-15

    Solidification behaviors of Sn-9Zn-xAg lead-free solder alloys, which vary with Ag content, are examined by using scanning electron microscopy, electron probe microanalysis, X-ray analysis, computer aided-cooling curve analysis and differential scanning calorimetry. The backscattered images and X-ray diffraction patterns indicate that with the addition of two silver intermetallic compounds; {gamma}-Ag{sub 5}Zn{sub 8} and {epsilon}-AgZn{sub 3}, form in the expense of zinc phase. The solid fraction versus temperature relationship and microstructure analysis show that Sn-Zn eutectic structures appear following the formation of primary tin. It is concluded in this study that the complicated solidification process of Sn-9Zn-xAg alloys can be described as L (liquid) {sup {yields}} L + {gamma}-Ag{sub 5}Zn{sub 8} {sup {yields}} L + {gamma}-Ag{sub 5}Zn{sub 8} + {epsilon}-AgZn{sub 3} {sup {yields}} L + {gamma}-Ag{sub 5}Zn{sub 8} + {epsilon}-AgZn{sub 3} + {beta}-Sn {sup {yields}} {gamma}-Ag{sub 5}Zn{sub 8} + {epsilon}-AgZn{sub 3} + {beta}-Sn + eutectic (Sn + Zn)

  7. Influence of Fe-rich intermetallics on solidification defects in Al–Si–Cu alloys

    International Nuclear Information System (INIS)

    To better understand the influence of Fe-rich intermetallics on solidification defect formation, fast in situ synchrotron X-ray tomographic microscopy experiments were performed on a commercial A319 alloy (Al–7.5Si–3.5Cu, wt.%) with 0.2 and 0.6 wt.% Fe. Real-time observations during solidification and semi-solid deformation experiments reveal that β-intermetallics contribute via several different mechanisms to porosity formation and hot tearing susceptibility. While β-intermetallics were not observed to nucleate porosity directly, they do block interdendritic channels, thereby reducing the shrinkage feeding, and increasing pore tortuosity. Pores also grow preferentially along the surface of the β-intermetallics, suggesting that the β-phase has a lower gas–solid interfacial energy than α-Al, thus assisting in increasing pore volume. During uniaxial tension experiments, the ductile failure of the semi-solid, intermetallic-poor, base alloy transitions to a brittle-like failure when a large amount of β-intermetallics are present. In all post-failure microstructures, internal damage was preferentially orientated perpendicular to the loading direction, agreeing with prior experimental and numerical studies

  8. Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

    Science.gov (United States)

    Ahmad, R.; Asmael, M. B. A.

    2016-05-01

    The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

  9. Multiscale modelling of solidification microstructures, including microsegregation and microporosity, in an Al-Si-Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, P.D.; Chirazi, A.; Atwood, R.C.; Wang, W

    2004-01-25

    Phase transition phenomena in metallic alloys involve complex physical processes occurring over a wide range of temporal, spatial and energy scales. Multiscale modelling is a powerful methodology for understanding these complex systems. In this paper, a multiscale model of grain and pore formation is presented during solidification. At the microscale, a combined stochastic-deterministic approach based on the cellular automata method is used to solve multicomponent diffusion in a three-phase system (liquid, solid and gas), simulating the nucleation and growth of both grains and pores. The impingement of the growing pores upon the developing solid is also solved to predict the tortuous shape of the porosity, a critical factor for fatigue properties. The micromodel is coupled with a finite element method (FEM) solution of the macroscale heat transfer and fluid flow in industrial castings through the temperature and pressure fields. The result model was used to investigate the influence of local solidification time, hydrogen content, local metallostatic pressure and alloy composition upon the predicted grain structure and pore morphology. Comparison of the model predictions to both laboratory and industrial scale castings are presented.

  10. Containerless processing and rapid solidification of Nb-Si alloys of hypereutectic composition

    Science.gov (United States)

    Hofmeister, W. H.; Bayuzick, R. J.; Robinson, M. B.; Bertero, G. A.

    1991-01-01

    A combination of bulk undercooling in an electromagnetic levitation apparatus and splat quenching between two copper plates is used to process Nb-Si alloys in order to maximize rapid solidification conditions and minimize the effects of recalescence, with emphasis on the solidification of characteristics of alloys in the 21 to 27 at. pct Si range of composition. SEM and TEM as well as X-ray diffraction are used to characterize the microstructures of the processed samples. In the range of compositions studied, the splat-quenched drops always formed the tetragonal Nb3Si phase directly from the liquid. Drops solidified in the coil were characterized by the presence of the primary intermetallic Nb5Si3 and the absence of both peritectic Nb3Si and the equilibrium eutectic. In these cases, a metastable alpha-Nb + beta-Nb5Si3 eutectic formed. The results are discussed in terms of possible metastable configurations of the Nb-Si phase diagram as well as concepts of nucleation and growth kinetics applied to the Nb3Si and Nb5Si3 intermetallics.

  11. Phase-Field Simulation of Microstructure Evolution in Industrial A2214 Alloy During Solidification

    Science.gov (United States)

    Wei, Ming; Tang, Ying; Zhang, Lijun; Sun, Weihua; Du, Yong

    2015-07-01

    By linking to the thermodynamic and atomic mobility databases in Al alloys well established in our research group, the microstructure evolution in industrial A2214 alloy (Al-4.5Cu-0.5Mg-1.0Si, in wt pct) during solidification process was studied by means of two-dimensional phase-field simulation via MICRostructure Evolution Simulation Software in the framework of the multi-phase-field formalism. The thermophysical parameters including interfacial energies and interfacial mobilities were carefully chosen for reproducing the experimental features. The solidification sequence due to the present phase-field simulation conforms to both equilibrium calculation and Scheil simulation. The predicted microstructure reproduces the experimental data very well. These facts indicate that a quantitative phase-field simulation was achieved in the present work. Moreover, the mechanisms of characteristic patterns and microstructure formation were revealed with the aid of the phase-field simulation. In addition, the effect of cooling rate on the secondary dendrite arm spacing and microsegregation was also investigated through comprehensive comparison with the experimental data.

  12. In Situ X-Ray Observations of Dendritic Fragmentation During Directional Solidification of a Sn-Bi Alloy

    Science.gov (United States)

    Gibbs, John W.; Tourret, Damien; Gibbs, Paul J.; Imhoff, Seth D.; Gibbs, Meghan J.; Walker, Brandon A.; Fezzaa, Kamel; Clarke, Amy J.

    2016-01-01

    Dendrite fragmentation is an important phenomenon in microstructural development during solidification. For instance, it plays a key role in initiating the columnar-to-equiaxed transition (CET). Here, we use x-ray radiography to study dendrite fragmentation rate in a Sn-39.5 wt.% Bi alloy during directional solidification. Experiments were performed in which solidification was parallel and anti-parallel to gravity, leading to significantly different fragmentation rates. We quantify the distribution of fragmentation rate as a function of distance from the solidification front, time in the mushy zone, and volume fraction of solid. While the observed fragmentation rate can be high, there is no evidence of a CET, illustrating that it requires more than just fragmentation to occur.

  13. Hot corrosion resistance of nickel-chromium-aluminum alloys

    Science.gov (United States)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  14. Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions

    Science.gov (United States)

    Gandin, Charles-Andre; Ratke, Lorenz

    2008-01-01

    The Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MSL-CETSOL and MICAST) are two investigations which supports research into metallurgical solidification, semiconductor crystal growth (Bridgman and zone melting), and measurement of thermo-physical properties of materials. This is a cooperative investigation with the European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) for accommodation and operation aboard the International Space Station (ISS). Research Summary: Materials Science Laboratory - Columnar-to-Equiaxed Transition in Solidification Processing (CETSOL) and Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions (MICAST) are two complementary investigations which will examine different growth patterns and evolution of microstructures during crystallization of metallic alloys in microgravity. The aim of these experiments is to deepen the quantitative understanding of the physical principles that govern solidification processes in cast alloys by directional solidification.

  15. Investigation of the Precipitation Behavior in Aluminum Based Alloys

    KAUST Repository

    Khushaim, Muna S.

    2015-11-30

    The transportation industries are constantly striving to achieve minimum weight to cut fuel consumption and improve overall performance. Different innovative design strategies have been placed and directed toward weight saving combined with good mechanical behavior. Among different materials, aluminum-based alloys play a key role in modern engineering and are widely used in construction components because of their light weight and superior mechanical properties. Introduction of different nano-structure features can improve the service and the physical properties of such alloys. For intelligent microstructure design in the complex Al-based alloy, it is important to gain a deep physical understanding of the correlation between the microstructure and macroscopic properties, and thus atom probe tomography with its exceptional capabilities of spatially resolution and quantitative chemical analyses is presented as a sophisticated analytical tool to elucidate the underlying process of precipitation phenomena in aluminum alloys. A complete study examining the influence of common industrial heat treatment on the precipitation kinetics and phase transformations of complex aluminum alloy is performed. The qualitative evaluation results of the precipitation kinetics and phase transformation as functions of the heat treatment conditions are translated to engineer a complex aluminum alloy. The study demonstrates the ability to construct a robust microstructure with an excellent hardness behavior by applying a low-energy-consumption, cost-effective method. The proposed strategy to engineer complex aluminum alloys is based on both mechanical strategy and intelligent microstructural design. An intelligent microstructural design requires an investigation of the different strengthen phases, such as T1 (Al2CuLi), θ′(Al2Cu), β′(Al3Zr) and δ′(Al3Li). Therefore, the early stage of phase decomposition is examined in different binary Al-Li and Al-Cu alloys together with different

  16. Fatigue crack propagation of new aluminum lithium alloy bonded with titanium alloy strap

    Institute of Scientific and Technical Information of China (English)

    Sun Zhenqi; Huang Minghui

    2013-01-01

    A new type of aluminum lithium alloy (A1-Li alloy) Al-Li-S-4 was investigated by test in this paper.Alloy plate of 400 mm × 140 mm × 6 mm with single edge notch was made into samples bonded with Ti-6Al-4V alloy (Ti alloy) strap by FM 94 film adhesive after the surface was treated.Fatigue crack growth of samples was investigated under cyclic loading with stress ratio (R) of 0.1 and load amplitude constant.The results show that Al-Li alloy plate bonded with Ti alloy strap could retard fatigue crack propagation.Retardation effect is related with width and thickness of strap.Flaws have an observable effect on crack propagation direction.

  17. Effects of P+Cr complex modification and solidification conditions on microstructure of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

    OpenAIRE

    Zhang Haitao; Zuo Kesheng; Han Xing

    2014-01-01

    Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observ...

  18. Research of Plasma Spraying Process on Aluminum-Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Patricija Kavaliauskaitė

    2016-04-01

    Full Text Available The article examines plasma sprayed 95Ni-5Al coatings on alu-minum-magnesium (Mg ≈ 2,6‒3,6 % alloy substrate. Alumi-num-magnesium samples prior spraying were prepared with mechanical treatment (blasting with Al2O3. 95Ni-5Al coatings on aluminum-magnesium alloys were sprayed with different parameters of process and coating‘s thickness, porosity, micro-hardness and microstructure were evaluated. Also numerical simulations in electric and magnetic phenomena of plasma spray-ing were carried out.

  19. Cracking susceptibility of aluminum alloys during laser welding

    Directory of Open Access Journals (Sweden)

    Lara Abbaschian

    2003-06-01

    Full Text Available The influence of laser parameters in welding aluminum alloys was studied in order to reduce hot cracking. The extension of cracks at the welding surface was used as a cracking susceptibility (CS index. It has been shown that the CS changes with changing welding velocity for binary Al-Cu alloys. In general, the CS index increased until a maximum velocity and then dropped to zero, generating a typical lambda-curve. This curve is due to two different mechanisms: 1 the refinement of porosities with increasing velocity and 2 the changes in the liquid fraction due to decreasing microsegregation with increasing velocities.

  20. Reconstruction of the heat transfer coefficient in the problem of binary alloy solidification with application of the broken line model

    Directory of Open Access Journals (Sweden)

    D. Słota

    2011-10-01

    Full Text Available In the paper, solution of the inverse problem is presented, which consists in determination of the heat transfer coefficient during the process of binary alloy solidification for the known temperature measurements in the selected points of the cast. In the considered model distribution of temperature is described with the aid of Stefan problem with the varying liquidus temperature depending on the concentration of alloy component. Whereas, for description of the concentration the broken line model is used.

  1. Reconstruction of the heat transfer coefficient in the problem of binary alloy solidification with application of the broken line model

    OpenAIRE

    D. Słota; E. Hetmaniok; R. Wituła

    2011-01-01

    In the paper, solution of the inverse problem is presented, which consists in determination of the heat transfer coefficient during the process of binary alloy solidification for the known temperature measurements in the selected points of the cast. In the considered model distribution of temperature is described with the aid of Stefan problem with the varying liquidus temperature depending on the concentration of alloy component. Whereas, for description of the concentration the broken line ...

  2. Solidification of metals and alloys under microgravity conditions; Bisho juryoku kankyo deno kinzoku oyobi gokin no gyoko

    Energy Technology Data Exchange (ETDEWEB)

    Motegi, T. [Chiba Institute of Technology, Chiba (Japan)

    1998-03-20

    Studies on the difference of solidified textures of metals and alloys under microgravity conditions from conventional ones on the earth, and the possibility of new material creation are very exciting. Features of microgravity environment in melting and solidification of metals are no thermal convection, and mass transfer caused only by diffusion. Even in alloys where the second phase molten component separates by difference in density on the earth, homogeneous textures are obtained because of no floatation and sedimentation. Melting and solidification without vessels allows to produce high-purity materials because of no invasion of impurities from vessels. No static pressure can eliminate distortions of crystals due to dead weight. No defects are observed because of no disturbance of atomic sequences. Referring to various experiments on metals under microgravity conditions, this paper outlines supercooling solidification of metal melts, solidification of single-phase alloys and multi-phase alloys such as eutectic and peritectic system ones, particle-dispersing composite materials, and the behavior of gases in molten metals. 35 refs., 8 figs., 2 tabs.

  3. Plasma spraying of beryllium and beryllium-aluminum-silver alloys

    International Nuclear Information System (INIS)

    A preliminary investigation on plasma-spraying of beryllium and a beryllium-aluminum 4% silver alloy was done at the Los Alamos National Laboratory's Beryllium Atomization and Thermal Spray Facility (BATSF). Spherical Be and Be-Al-4%Ag powders, which were produced by centrifugal atomization, were used as feedstock material for plasma-spraying. The spherical morphology of the powders allowed for better feeding of fine (<38 μm) powders into the plasma-spray torch. The difference in the as-deposited densities and deposit efficiencies of the two plasma-sprayed powders will be discussed along with the effect of processing parameters on the as-deposited microstructure of the Be-Al-4%Ag. This investigation represents ongoing research to develop and characterize plasma-spraying of beryllium and beryllium-aluminum alloys for magnetic fusion and aerospace applications

  4. Die Casting Mold Design for Aluminum Alloy Shell of Instrument

    Directory of Open Access Journals (Sweden)

    Li Yuanyuan

    2015-01-01

    Full Text Available This paper is about die casting mold design for aluminum alloy shell of instrument. Three-dimensional model of the casting and mold are designed by using Pro/Engineer and AutoCad which can analyze forming quality. Digital design and theoretical calculation can greatly shorten product development cycle and mold design cycle, improve the accuracy of product design and mold design, and reduce the cost of mold design.

  5. Experimental Studies of Cold Roll Bonded Aluminum Alloys

    OpenAIRE

    Lauvdal, Steinar

    2011-01-01

    This master’s thesis is based on experimental studies of the parameters influencing cold roll bonding (CRB) of the aluminum alloys AA1200 and AA3103,in the work hardened and annealed condition. The effect on the bond strength from the preparations parameters as degreasing agent, scratch brushing and exposure time for oxide growth is investigated in comparison to former studies. Further the effect of rolling speed and effect from contributing factors from the different testing methods is ...

  6. Linear Anomaly in Welded 2219-T87 Aluminum Alloy

    Science.gov (United States)

    Jemian, Wartan A.

    1987-01-01

    Study of causes and significance of two types of linear anomalies sometimes appearing in radiographs of welds described in preliminary report. Manifested as light or dark linear features parallel to weld line in radiograph of weld. Contains diagrams and descriptions of phenomena occurring during welding process. Includes microdensitometer traces from x-radiographs of actual welds and from computer simulations based calculation of x-ray transmission through assumed weld structures. Concludes anomalies not unique to 2219-T87 aluminum alloy.

  7. Residual stress profiling of an aluminum alloy by laser ultrasonics

    Institute of Scientific and Technical Information of China (English)

    PAN Yondong; QIAN Menglu; XU Weijiang; M. OURAK

    2004-01-01

    A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.

  8. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn- 10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercool- ings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition "dendrite→monotectic cell" happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  9. Residual stress in quenched 7075 aluminum alloy thick plates

    Institute of Scientific and Technical Information of China (English)

    林高用; 张辉; 朱伟; 彭大暑; 梁轩; 周鸿章

    2003-01-01

    The influence of quenching water temperature, pre-stretching amount and aging temperature and times on residual stress in 7075 aluminum thick plate was studied by the measurement of residual stress using drilling hole method. The results indicate that residual stress decreases by 30% with increasing quenching water temperature from 40 ℃ to 80 ℃, 20% with increasing aging temperature from 100 ℃ to 180 ℃,and 20% with increasing aging times from 5 h to 25 h. Also, residual stress decreases to zero with increasing pre-stretching amount to approximately 2%. Hence, residual stress in 7075 aluminum thick plate is reduced by the control of quenching water temperature at 80 ℃ and with pre-stretching amount of about 2%. An optimal aging temperature and time should be systemically investigated to obtain combination of high mechanical performances and lower residual stress for manufacturing of 7075 aluminum alloy thick plates.

  10. Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    C.M. Cheng

    2007-01-01

    This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW (gas tungsten arc welding) butt-welding to analyze and compare the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

  11. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    International Nuclear Information System (INIS)

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting)

  12. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    Science.gov (United States)

    Chirita, G.; Stefanescu, I.; Soares, D.; Cruz, D.; Silva, F. S.

    2008-02-01

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting).

  13. Prediction of Hot Tear Formation in Vertical DC Casting of Aluminum Billets Using a Granular Approach

    OpenAIRE

    Sistaninia, M.; Drezet, J. -M.; Phillion, A. B.; Rappaz, M.

    2013-01-01

    A coupled hydromechanical granular model aimed at predicting hot tear formation and stress-strain behavior in metallic alloys during solidification is applied to the semicontinuous direct chill casting of aluminum alloy round billets. This granular model consists of four separate three-dimensional (3D) modules: (I) a solidification module that is used for generating the solid-liquid geometry at a given solid fraction, (II) a fluid flow module that is used to calculate the solidification shrin...

  14. In situ and real-time 3-D microtomography investigation of dendritic solidification in an Al-10 wt.% Cu alloy

    International Nuclear Information System (INIS)

    The microstructural evolution of an Al-10 wt.% Cu alloy was investigated during solidification at constant cooling rate by in situ synchrotron X-ray microtomography with a resolution of 2.8 μm. Solidification of this alloy leads to a coarse dendritic microstructure which was fully characterized in terms of variation with temperature of the solid fraction, the specific surface area of the solid-liquid interface and the local curvatures of the solid phase. By analysing the evolution with solid fraction of individual dendrites, at least two coarsening mechanisms were clearly identified in addition to solidification growth. The first mechanism involves remelting of small secondary dendrite arms to the benefit of bigger adjacent arms. The second is the coalescence of adjacent secondary arms, with progressive filling of the inter-arm spacing and coalescence at the tips. Although this mechanism preferentially occurs at high solid fractions, these results show that the evolution of the dendritic microstructure during solidification is complex and involves the occurrence of various mechanisms operating concurrently. In situ X-ray tomography thus allows revisiting the various models which have been proposed to account for dendrite coarsening during solidification

  15. Interfacial morphology development and solute trapping behavior during rapid solidification of an Al–Li–Cu alloy

    International Nuclear Information System (INIS)

    An aluminum–lithium–copper alloy was rapidly solidified via the electrospark deposition process. High-resolution scanning electron microscopy (HR-SEM), time-of-flight secondary-ion-mass-spectroscopy (TOF-SIMS) and atom probe tomography (APT) were employed to investigate the distribution of solute within the deposited materials. The TOF-SIMS data revealed evidence that solute trapping of lithium occurred during solidification, while SEM and APT revealed the presence of fine copper-rich cells within the microstructure (∼30–60 nm in width). This morphology correlated directly with the microstructural morphology predicted by the Kurz–Giovanola–Trivedi (KGT) model for microstructural development during rapid solidification. The KGT model, which can be used to describe the planar–cellular transition within a microstructure, then predicted a solidification front velocity of ∼1 m s−1 being realized during electrospark deposition solidification. This SFV corroborated the chemical mapping data, and therefore supported the solute trapping hypothesis, as the continuous growth model for solute trapping as developed by Aziz and Kaplan (Acta Metallurgica 1988; 36:2335) predicts significant trapping of lithium at a SFV of 1 m s−1. Finally APT revealed the presence of Al3Li phase upon the copper-rich cell walls. It was then determined that the Al3Li was not formed during solidification, as predicted by a time-dependent nucleation model for phase prediction during rapid solidification, and therefore is the result of a subsequent aging process

  16. Dynamic Crystallization: An Influence on Degree of Prior Deformation and Mechanical Strength of 6063 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Gbenebor, O.P

    2012-09-01

    Full Text Available This research is aimed at investigating the influence dynamic solidification of melts on degree of mechanical deformation and mechanical strength of 6063 aluminum alloy. Cylindrical samples of 14mm diameter and 140mm long were die cast following two techniques – vibration and static. Prior deformation via forging was imposed on each solidified sample to achieve 7%, 14%, 21% and 28% thickness reductions respectively for each casting technique. Average deformation load, average hammer velocities and the average energy absorbed were recorded. Tensile properties of each sample were studied via the use of Monsanto tensometer. Mechanical agitation of mould and its content increased the machinability of the alloy even at higer pre deformation. This was justified by the failure of the 28% reduction sample cast on static floor during machining to a tensile piece. The energy absorbed during deformation influences the tensile strength of the material. This increases with increase in percentage deformation except for 28% reduction whose magnitude was lower than that subjected to 21% reduction; vibrated samples possessed superior properties. From results obtained, vibrating a sample and subjecting to 21% pre-deformation possessed the best tensile strength.

  17. Synthesis of bulk nanostructured aluminum alloy component through vacuum plasma spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Laha, T. [Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, EC 3464, Miami, FL 33174 (United States); Agarwal, A. [Mechanical and Materials Engineering, Florida International University, 10555 West Flagler Street, EC 3464, Miami, FL 33174 (United States)]. E-mail: agarwala@fiu.edu; McKechnie, T. [Plasma Processes Inc., Huntsville, AL 35811 (United States); Rea, K. [Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States); Seal, S. [Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816 (United States)

    2005-12-15

    The benefits of large-size engineering components with nanocrystalline structure (providing improved strength) are yet to be realized due to processing difficulties and associated grain growth problems. In this work, a free-standing bulk nanocrystalline structure of hypereutectic aluminum alloy (Al-21wt.%Si) has been fabricated through the vacuum plasma spray (VPS) forming technique using micron-size powder feedstock. Optical microscopy, scanning electron microscopy and transmission electron microscopy have been used to investigate the evolution of multi-scale microstructure as the result of rapid solidification in VPS forming process. The characterization implies the presence of nanosized eutectic Al-Si grains (25-100 nm) with uniformly distributed ultrafine primary silicon particles of submicron size. The effect of microstructural evolution on mechanical properties has been studied by tensile testing and microhardness measurement. A considerable improvement in ultimate tensile strength and hardness of the sprayed deposit has been observed in comparison with conventionally cast hypereutectic Al-17wt.%Si alloys.

  18. The characteristics of aluminum-scandium alloys processed by ECAP

    International Nuclear Information System (INIS)

    Aluminum-scandium alloys were prepared having different scandium additions of 0.2, 1.0 and 2.0 wt.% and these alloys were processed by equal-channel angular pressing (ECAP) at 473 K. The results show the grain refinement of the aluminum matrix and the morphology of the Al3Sc precipitates depends strongly on the scandium concentration. The tensile properties were evaluated after ECAP by pulling to failure at initial strain rates from 1.0 x 10-3 to 1.0 x 10-1 s-1. The Al-1% Sc alloy exhibited the highest tensile strength of ∼250 MPa at a strain rate of 1.0 x 10-1 s-1. This alloy also exhibited a superior grain refinement of ∼0.4 μm after ECAP where this is attributed to a smaller initial grain size and an optimum volume fraction of dispersed Al3Sc precipitates having both micrometer and nanometer sizes.

  19. In-situ processing of aluminum nitride particle reinforced aluminum alloy composites

    Science.gov (United States)

    Zheng, Qingjun

    Discontinuously reinforced aluminum alloy composites (DRACs) have potential applications in automotive, electronic packaging, and recreation industries. Conventional processing of DRACs is by incorporation of ceramic particles/whiskers/fibers into matrix alloys. Because of the high cost of ceramic particles, DRACs are expensive. The goal of this work was to develop a low-cost route of AlN-Al DRACs processing through bubbling and reacting nitrogen and ammonia gases with aluminum alloy melt in the temperature range of 1373--1523 K. Thermodynamic analysis of AlN-Al alloy system was performed based on Gibbs energy minimization theory. AlN is stable in aluminum, Al-Mg, Al-Si, Al-Zn, and Al-Li alloys over the whole temperature range for application and processing of DRACs. Experiments were carried out to form AlN by bubbling nitrogen and ammonia gases through aluminum, Al-Mg, and Al-Si alloy melts. Products were characterized with XRD, SEM, and EDX. The results showed that in-situ processing of AlN reinforced DRACs is technically feasible. Significant AlN was synthesized by bubbling deoxidized nitrogen and ammonia gases. When nitrogen gas was used as the nitrogen precursor, the AlN particles formed in-situ are small in size, (interface. In comparison with nitrogen gas, bubbling ammonia led to formation of AlN particles in smaller size (about 2 mum or less) at a significantly higher rate. Ammonia is not stable and dissociated into nitrogen and hydrogen at reaction temperatures. The hydrogen functions as oxygen-getter at the interface and benefits chemisorption of nitrogen, thereby promoting the formation of AlN. The overall process of AlN formation was modeled using two-film model. For nitrogen bubbling gas, the whole process is controlled by chemisorption of nitrogen molecules at the gas bubble - aluminum melt interface. For ammonia precursor, the rate of the overall process is limited by the mass transfer of nitrogen atoms in the liquid boundary layer. The models agree

  20. Hydrogen solubility in aluminum-copper alloys

    International Nuclear Information System (INIS)

    Hydrogen solubility(S (10-2 cm3g-1atm-0.5)) in Al-(0-50mass%) Cu alloys were measured by a desorption technique for the thermally gas-charged cylindrical samples which were solidified unidirectionally in the pure nitrogen gas flow (sample ND). The solubility was compared with that in samples melted and cast in vacuum (sample VM) and with that in samples melted in air and cast into a metal mould (sample AM). Since the solubility S (ND) was almost equal to S (VM), samples ND were found to have no voids of gas defects such as porosity and cavity. In the region of α-solid solution (Cuθ) and got to the higher hydrogen solubility in the θ-phase (Sθ), according to the equation S (ND) = Sα (1-fθ) + Sθfθ. S (AM) was greater than S (ND) due to the trapped hydrogen gas in the voids. In the alloy of the eutectic composition (33 mass%Cu) which had little voids, S (33AM) was smaller than S (33ND). This was attributed to anon-equilibrium or suppressed charging of hydrogen due to the trapping of hydrogen in a finer metallic structure of a sample AM. (author)

  1. Metastable phase separation and rapid solidification of undercooled Co-Cu alloy under different conditions

    Institute of Scientific and Technical Information of China (English)

    Cao Chong-De

    2006-01-01

    The metastable liquid phase separation and rapid solidification behaviours of Co61.8Cu38.2 alloy were investigated by using differential thermal analysis (DTA) in combination with glass fluxing,electromagnetic levitation (EML) and drop tube techniques.It is found that the liquid phase separation process and the solidification microstructures intensively depend on the experimental processing parameters,such as undercooling level,cooling rate,gravity level,liquid surface tension and the wetting state of crucible.Large undercooling and surface tension difference of the two liquids tend to facilitate further separation and cause severe macrosegregation.On the other hand,rapid cooling and low gravity effectively suppress the coalescence of the minority phase.Severe macrosegregation patterns are formed in the bulk samples processed by both DTA and EML.In contrast,disperse structures with fine spherical Cu-rich spheres homogeneously distributed in the matrix of Co-rich phase have been obtained in drop tube.

  2. Kinetic competition during duplex partitionless solidification in Ni-V alloys

    International Nuclear Information System (INIS)

    A structure composed of both partitionless face-centered cubic (α-fcc) and body-centered cubic (β-bcc) phases has been observed following high undercooling solidification of nickel-vanadium (Ni-V) alloys in the composition range 47--51.7 at.% V. Containerless processing and rapid solidification suppresses the formation of the equilibrium σ phase and results in the simultaneous formation of partitionless fcc and bcc phases. Transmission electron microscopy analysis has identified regions in which 0.1--1 microm α and β grains co-exist in a duplex structure. A nucleation and growth kinetics analysis has been developed to describe the conditions under which this structure may form. Thermodynamic and kinetic arguments have been used to provide bounds on various kinetic parameters. These bounds indicate that the nucleation rates for α and β must be larger than about 1027 m-3s-1 to account for the number of grains observed in the time available for nucleation, and the growth rates are constrained to be larger than about 1 m/s to account for complete solute trapping

  3. Electrorefining of aluminum alloy in ionic liquids at low temperatures

    Directory of Open Access Journals (Sweden)

    Kamavaram V.

    2003-01-01

    Full Text Available The electrorefining of aluminum alloy (A360 in ionic liquids at low temperatures has been investigated. The ionic liquid electrolyte was prepared by mixing anhydrous AlCl3 and 1-Butyl-3- methylimidazolium chloride (BMIC in appropriate proportions. The effect of the cell voltage temperature, and the composition of the electrolyte on the electrorefining process has been studied. The characterization of the deposited aluminum was performed using scanning electron microscopy (SEM and X-ray diffraction (XRD techniques. The influence of experimental parameters such as cell voltage and concentration of AlCl3 in the electrolyte on the deposit morphology was discussed. The composition of the aluminum deposits was analyzed using X-ray fluorescence spectrometer (XRF. Aluminum deposits with purity higher than 99.89 % were obtained. At a cell voltage of 1.0 V vs. Al/Al(III, the energy consumption was about 3 kWh/kg-Al. The main advantage of the process is low energy consumption compared to the existing industrial aluminum refining process.

  4. The stamping behavior of an early-aged 6061 aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: → Excellent stamping performance of 6061 aluminum alloy. → Improvement of stamping behavior of 6061 aluminum alloy by early-aging. → Observation of dislocations and precipitates using Weak-Beam Dark-Field technique. -- Abstract: The stamping behavior of 6061 aluminum alloy with various conditions of early-aging is investigated in the present study. The relationship between the stamping performance, microstructure and mechanical property for this alloy is also discussed. Experimental results show that the 6061 aluminum alloy with a 10-30 min. early-aging at 160 oC will exhibit excellent stamping performance. The burnished surface of these treated alloys can reach a quite high value of 47%. Meanwhile, the mechanical strength and impact toughness have important effects on the stamping behavior of 6061 aluminum alloy. The moderate values of mechanical strength and toughness will exhibit an optimal stamping performance.

  5. Enhancement of superplastic formability in a high strength aluminum alloy

    Science.gov (United States)

    Agrawal, S. P.; Turk, G. R.; Vastava, R.

    1988-01-01

    A 7475 aluminum alloy was developed for superplastic forming (SPF). By lowering the Fe and Si contents in this alloy significantly below their normal levels and optimizing the thermomechanical processing to produce sheet, over 2000 percent thickness strain to failure was obtained. The microstructure, elevated-temperature uniaxial and biaxial tension, and cavitation behavior of the alloy were determined. In addition, a constitutive model was used to form a generic structural shape from which mechanical test specimens were removed and post-SPF characteristics were evaluated. The constitutive model included both material strain hardening and strain rate hardening effects, and was verified by accurately predicting forming cycles which resulted in successful component forming. Stress-life fatigue, stress rupture, and room and elevated temperature tensile tests were conducted on the formed material.

  6. Mechanical properties of hot rolled 2519 aluminum alloy plate

    Institute of Scientific and Technical Information of China (English)

    彭大暑; 陈险峰; 林启权; 张辉

    2003-01-01

    The effects of differences of temper on mechanical properties of T6, T7 and T8 plates of aluminum alloy 2519 were studied. The stress corrosion cracking(SCC) sensitivity was evaluated with parameters such as Kσ and Kδ.Tensile tests were divided into two groups: one was performed on tensile specimens without pre-corrosion, the other was performed on tensile specimens which were pre-corroded in 3.5%NaCl+1%H2O2 solution at 25 ℃.The results show that SCC resistance of alloy 2519 ranks in the order of T8>T7>T6 and the mechanical properties rank in the order of T6>T8>T7. SEM fractographs of the failed specimen show that the SCC sensitivity can be determined by the distribution of the second phase particles and size and the shape of grains in the alloy.

  7. Effects of shot peening on internal friction in CP aluminum and aluminum alloy 6008

    Energy Technology Data Exchange (ETDEWEB)

    Flejszar, Aneta; Ludian, Tomasz; Mielczarek, Agnieszka; Riehemann, Werner; Wagner, Lothar [Clausthal Univ. of Science and Technology, Inst. of Materials Science and Technology, Clausthal-Zellerfeld (Germany)

    2009-06-15

    The strain-amplitude-dependent damping of bending beams of aluminum alloy 6008 and CP aluminum was measured at room temperature after different heat treatments and after shot peening. Shot peening led to an increase of damping in almost the whole measured amplitude strain range from 10{sup -6} to 10{sup -3} for CP aluminum. Strong ageing effects at room temperature were observed immediately after the shot peening process, namely an increase of the amplitude dependent part and a decrease of the amplitude-independent part of damping. After about 2700 h, ageing of the samples had saturated. For aluminum alloy 6008 much smaller ageing effects were found being due to compensating effects like formation of Cottrell clouds, precipitation of G.P. - zones, and the reduction of foreign atoms in solid solution. The found amplitude-dependent damping can be explained by the reversible movement of dislocations between strong pinning points like, e.g., precipitates and weak pinning points like solid solute atoms as proposed by the dislocation damping theory of Granato and Luecke. Using this model the found ageing effects can be explained by the diffusion of solid solute atoms to the dislocations. (orig.)

  8. A High-Fe Aluminum Matrix Welding Filler Metal for Hardfacing Aluminum-Silicon Alloys

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A high-Fe containing aluminum matrix filler metal for hardfacing aluminum-silicon alloys has been developed by using iron,nickel,and silicon as the major strengthening elements,and by measuring mechanical properties,room temperature and high temperature wear tests,and microstructural analysis.The filler metal,which contains 3.0%-5.0% Fe and 11.0%-13.0% Si,exhibits an excellent weldability.The as-cast and as-welded microstructures for the filler metal are of uniformly distribution and its dispersed network of hard phase is enriched with Al-Si-Fe-Ni.The filler metal shows high mechanical properties and wear resistance at both room temperature and high temperatures.The deposited metal has a better resistance to impact wear at 220℃ than that of substrate Al-Si-Mg-Cu piston alloy;at room temperature,the deposited metal has an equivalent resistance to slide wear with lubrication as that of a hyper-eutectic aluminum-silicon alloy with 27% Si and 1% Ni.

  9. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    Science.gov (United States)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  10. Dilution of molybdenum on aluminum during laser surface alloying

    International Nuclear Information System (INIS)

    Highlights: •Laser surface alloying significantly increased the solubility of transition metal. •Laser surface alloying produced dense coating with good metallurgical bonding. •Laser process parameters greatly influenced the evolution of various intermetallics. •Computationally predicted results closely matched with experimental findings. •Ability to generalize present model to other metal-transition metal systems. -- Abstract: A multiphysics based computational model was developed to predict the dilution of molybdenum (Mo) on an aluminum (Al) substrate during the laser surface alloying process. The influence of laser surface alloying processing parameters such as input energy, scanning speed, and overlapping ratio on dilution of Mo in Al was explored via computational model. The computational model, closely predicts the melt pool geometry (width and depth) that subsequently helps in estimating dilution. It was observed that the dilution increases with the increase in laser power, while it decreases with the increase in scanning speed. The phase and microstructural analyses revealed the existence of Al5Mo intermetallic for most of the laser surface alloying processing conditions. However, at higher (3.18 × 107 J/m2) and lower (1.91 × 107 J/m2) laser energy densities, the Al8Mo3 intermetallic was also evolved. These experimental observations validate the model’s predictions and points to its reliability in predicting the expected intermetallics in Al–Mo system for various laser surfacing alloying processing conditions

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

    Science.gov (United States)

    Liang, S. M.; Schmid-Fetzer, R.

    2016-03-01

    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.

  12. Phase selection during solidification of undercooled Ni_(70.2)Si_(29.8) eutectic alloy

    Institute of Scientific and Technical Information of China (English)

    Yiping Lu; Tingju Li; Fu Yabo; Sun Jianbo; Luo Dawei; Gencang Yang; Yaohe Zhou

    2009-01-01

    High undercooling (about 392 K) was achieved in the bulk eutectic Ni_(70.2)Si_(29.8) alloy melt through glass fluxing combined with cyclic superheating. It is found that the metastable phases Ni_3Si_2 and NiSi are obtained through slow post-solidification when undercooling exceeds 240 K. The metastable phases are confirmed by using the method of X-ray diffraction and differential scanning calorimetry (DSC). Based on the principle of the free energy minimum and the transient nucleation theory, the phase selection of melt is investigated with regard to the metastable phases formation in the bulk undercooled eutectic Ni_(70.2)Si_(29.8) melts. The formation of metastable phases from undercooled Ni_(70.2)Si_(29.8) melts is ascribed to competitive nucleation with the undercooling, I.e. High undercooling facilitates the pref-erential nucleation of metastable phases.

  13. Aligned Solidification Structure of the MnBi Phase in Semisolidified Bi-Mn Alloy with a Static Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    Zhongming REN; Hui WANG; Kang DENG; Kuangdi XU

    2004-01-01

    The solidification structure of Bi-3 wt pct Mn alloy grown up in the semisolid zone under the influence of a static magnetic field (up to 1.0 T) and the relation of the magnetic property with the solidification structure have been investigated experimentally. It was shown that the primary phase MnBi crystals in the alloy aligned and oriented along the direction of the applied magnetic field. The orientating tendency and the average length of the elongated MnBi crystals increased with the increase of the applied field and the solidification time. Moreover, the remanence of the alloy along the aligned direction of the MnBi phase in the case of solidification with a magnetic field was apparently anisotropic and nearly double of that without the magnetic field. This indicated that the MnBi crystals oriented and aligned along their easy magnetization axis. A model was proposed to explain the alignment and orientation growth of the MnBi crystals in a magnetic field in terms of the magnetic anisotropy of the crystals and the magnetic interaction between them.

  14. From 2007 to 2010,China Will Manufacture More Than 10,000 Aluminum Alloy Railcars

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    <正>The clear advantage of the aluminum alloy rail- cars is the weight reduction.The deadweight of the aluminum alloy railcars usually does not exceed 8.5t each.The 52 motor train units used in the sixth nationwide railway speedup are all made of aluminum alloys except for the train units used in the line between Guangzhou and Shenzhen.It is estimated that in 2010,there are more than 10,000 railcars made of aluminum alloys,which will consume about 105kt alumi- num.

  15. Effect of vapor phase corrosion inhibitor on microbial corrosion of aluminum alloys.

    Science.gov (United States)

    Yang, S S; Ku, C H; Bor, H J; Lin, Y T

    1996-02-01

    Vapor phase corrosion inhibitors were used to investigate the antimicrobial activities and anticorrosion of aluminum alloy. Aspergillus flavus, A. niger, A. versicolor, Chaetomium globosum and Penicillium funiculosum had moderate to abundant growth on the aluminum alloy AA 1100 at Aw 0.901, while there was less growth at Aw 0.842. High humidity stimulated microbial growth and induced microbial corrosion. Dicyclohexylammonium carbonate had a high inhibitory effect on the growth of test fungi and the microbial corrosion of aluminum alloy, dicyclohexylammonium caprate and dicyclohexylammonium stearate were the next. Aluminum alloy coating with vapor phase corrosion inhibitor could prevent microbial growth and retard microbial corrosion. PMID:10592784

  16. Effect of a transverse magnetic field on solidification structure in directionally solidified Al-Cu-Ag ternary alloys

    Science.gov (United States)

    Guan, Guang; Du, Dafan; Fautrelle, Yves; Moreau, Rene; Ren, Zhongming; Li, Xi

    2015-07-01

    The effect of a transverse magnetic field on solidification structure in directionally solidified Al-Cu-Ag ternary alloys was investigated experimentally. The results show that the application of the transverse magnetic field significantly modified the solidification structures. Indeed, the magnetic field caused the formation of macrosegregation and the transformation of the liquid/solid interface from cellular to planar. Moreover, it was found that the magnetic field refined the eutectic cell and decreased the mushy zone length. This may be attributed to the thermoelectric magnetic convection between eutectic cells.

  17. Inverse problem for the solidification of binary alloy in the casting mould solved by using the bee optimization algorithm

    Science.gov (United States)

    Hetmaniok, Edyta

    2016-07-01

    In this paper the procedure for solving the inverse problem for the binary alloy solidification in the casting mould is presented. Proposed approach is based on the mathematical model suitable for describing the investigated solidification process, the lever arm model describing the macrosegregation process, the finite element method for solving the direct problem and the artificial bee colony algorithm for minimizing the functional expressing the error of approximate solution. Goal of the discussed inverse problem is the reconstruction of heat transfer coefficient and distribution of temperature in investigated region on the basis of known measurements of temperature.

  18. Inverse problem for the solidification of binary alloy in the casting mould solved by using the bee optimization algorithm

    Science.gov (United States)

    Hetmaniok, Edyta

    2015-08-01

    In this paper the procedure for solving the inverse problem for the binary alloy solidification in the casting mould is presented. Proposed approach is based on the mathematical model suitable for describing the investigated solidification process, the lever arm model describing the macrosegregation process, the finite element method for solving the direct problem and the artificial bee colony algorithm for minimizing the functional expressing the error of approximate solution. Goal of the discussed inverse problem is the reconstruction of heat transfer coefficient and distribution of temperature in investigated region on the basis of known measurements of temperature.

  19. Phase-field investigation on the non-equilibrium interface dynamics of rapid alloy solidification

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeong [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    solute trapping models are not rigorously verified due to the difficulty in experimentally measuring under rapid growth conditions. Moreover, since these solute trapping models include kinetic parameters which are difficult to directly measure from experiments, application of the solute trapping models or the associated analytic rapid solidification model is limited. These theoretical models for steady state rapid solidification which incorporate the solute trapping models do not describe the interdependency of solute diffusion, interface kinetics, and alloy thermodynamics. The phase-field approach allows calculating, spontaneously, the non-equilibrium growth effects of alloys and the associated time-dependent growth dynamics, without making the assumptions that solute partitioning is an explicit function of velocity, as is the current convention. In the research described here, by utilizing the phase-field model in the thin-interface limit, incorporating the anti-trapping current term, more quantitatively valid interface kinetics and solute diffusion across the interface are calculated. In order to sufficiently resolve the physical length scales (i.e. interface thickness and diffusion boundary length), grid spacings are continually adjusted in calculations. The full trajectories of transient planar growth dynamics under rapid directional solidification conditions with different pulling velocities are described. As a validation of a model, the predicted steady state conditions are consistent with the analytic approach for rapid growth. It was confirmed that rapid interface dynamics exhibits the abrupt acceleration of the planar front when the effect of the non-equilibrium solute partitioning at the interface becomes signi ficant. This is consistent with the previous linear stability analysis for the non-equilibrium interface dynamics. With an appropriate growth condition, the continuous oscillation dynamics was able to be simulated using continually adjusting grid

  20. Application of a criterion for cold cracking to casting high strength aluminum alloys

    NARCIS (Netherlands)

    Lalpoor, M.; Eskin, D.G.; Fjaer, H.G.; Ten Cate, A.; Ontijt, N.; Katgerman, L.

    2010-01-01

    Direct chill (DC) casting of high strength 7xxx series aluminium alloys is difficult mainly due to solidification cracking (hot cracks) and solid state cracking (cold cracks). Poor thermal properties along with extreme brittleness in the as-cast condition make DC-casting of such alloys a challenging

  1. Prediction of selected mechanical properties of ferrous alloys through computational modeling of solidification

    Science.gov (United States)

    Guo, Xinqing

    During the last decade, the casting solidification simulation that includes the evolution of microstructure has gained significant attention. A more recent goal is the development of a predictive tool which quantitatively links the processing parameters to the microstructure and finally to the properties of castings. With the continuous improvements in the computational abilities of computers, as well as because of the rapid development of numerical methods, the prediction of microstructure of ferrous casting has become feasible. Consequently, the problem of predicting the mechanical properties of the ferrous castings becomes a problem of establishing the quantitative relationships between the mechanical properties and the microstructures of the castings. The purpose of this study is to provide a fundamental understanding of the mechanical behavior of Fe-C alloys for a rather broad range of compositions and microstructures. Microstructure-properties relationships have been developed and implemented into a computer solidification model to improve the design and production of castings. In the mechanical properties model of gray iron presented in this dissertation, the main factors controlling the tensile strength and hardness are addressed. They include graphite flake length, pearlite content and interlamellar spacing. The influence of the microstructural features of ductile iron, including graphite nodule count, nodularity, fraction of graphite, fraction of ferrite, and fraction of pearlite, on the fracture mechanism and the mechanical properties are discussed in the model for ductile iron. In the case of carbon steel, the ferrite grain size, the fraction of ferrite, and the fraction of pearlite have been found to be the significant factors controlling the properties. It is noted that the formulae used in all of the models are based on physical metallurgical principles and the coefficients for the models are obtained through multiple regression on commercial

  2. Surface treatment of new type aluminum lithium alloy and fatigue crack behaviors of this alloy plate bonded with Ti–6Al–4V alloy strap

    International Nuclear Information System (INIS)

    Highlights: ► A new generation aluminum lithium alloy which special made for Chinese commercial plane was investigated. ► Pattern of aluminum lithium alloy and Ti alloy were shown after anodization. ► Crack propagation of samples bonded with different wide Ti straps were studied in this paper. -- Abstract: Samples consisting of new aluminum lithium alloy (Al–Li alloy) plate developed by the Aluminum Company of America and Ti–6Al–4V alloy (Ti alloy) plate were investigated. Plate of 400 mm × 140 mm × 2 mm with single edge notch was anodized in phosphoric solution and Ti alloy plate of 200 mm × 20 (40) mm × 2 mm was anodized in alkali solution. Patterns of two alloys were studied at original/anodized condition. And then, aluminum alloy and Ti alloy plates were assembled into a sample with FM 94 film adhesive. Fatigue crack behaviors of the sample were investigated under condition of nominal stress σ = 36 MPa and 54 MPa, stress ratio of 0.1. Testing results show that anodization treatment modifies alloys surface topography. Ti alloy bonding to Al–Li alloy plate effectively retards crack growth than that of Al–Li alloy plate. Fatigue life of sample bonded with Ti alloy strap improves about 62.5% than that of non-strap plate.

  3. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    Energy Technology Data Exchange (ETDEWEB)

    Cau Dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Lambertin, D.; Lahalle, H.; Antonucci, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Cannes, C.; Delpech, S. [Institut de Physique Nucléaire, CNRS, Univ. Paris-Sud 11, 91406 Orsay Cedex (France)

    2014-10-15

    Highlights: • Binders capable of reducing the pore solution pH compared with Portland cements are reviewed. • The binders are then tested against aluminum corrosion. • Corrosion of aluminum metal is minimal with magnesium phosphate cement. • The H{sub 2} release can be reduced still further by adding LiNO{sub 3} to the mixing solution. • Electrochemical characterizations show that aluminum tends to a passive state. - Abstract: In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  4. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    International Nuclear Information System (INIS)

    Highlights: • Binders capable of reducing the pore solution pH compared with Portland cements are reviewed. • The binders are then tested against aluminum corrosion. • Corrosion of aluminum metal is minimal with magnesium phosphate cement. • The H2 release can be reduced still further by adding LiNO3 to the mixing solution. • Electrochemical characterizations show that aluminum tends to a passive state. - Abstract: In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder

  5. The Effect of Impurities on the Processing of Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zi-Kui Liu; Shengjun Zhang; Qingyou Han; Vinod Sikka

    2007-04-23

    For this Aluminum Industry of the Future (IOF) project, the effect of impurities on the processing of aluminum alloys was systematically investigated. The work was carried out as a collaborative effort between the Pennsylvania State University and Oak Ridge National Laboratory. Industrial support was provided by ALCOA and ThermoCalc, Inc. The achievements described below were made. A method that combines first-principles calculation and calculation of phase diagrams (CALPHAD) was used to develop the multicomponent database Al-Ca-K-Li-Mg-Na. This method was extensively used in this project for the development of a thermodynamic database. The first-principles approach provided some thermodynamic property data that are not available in the open literature. These calculated results were used in the thermodynamic modeling as experimental data. Some of the thermodynamic property data are difficult, if not impossible, to measure. The method developed and used in this project allows the estimation of these data for thermodynamic database development. The multicomponent database Al-Ca-K-Li-Mg-Na was developed. Elements such as Ca, Li, Na, and K are impurities that strongly affect the formability and corrosion behavior of aluminum alloys. However, these impurity elements are not included in the commercial aluminum alloy database. The process of thermodynamic modeling began from Al-Na, Ca-Li, Li-Na, K-Na, and Li-K sub-binary systems. Then ternary and higher systems were extrapolated because of the lack of experimental information. Databases for five binary alloy systems and two ternary systems were developed. Along with other existing binary and ternary databases, the full database of the multicomponent Al-Ca-K-Li-Mg-Na system was completed in this project. The methodology in integrating with commercial or other aluminum alloy databases can be developed. The mechanism of sodium-induced high-temperature embrittlement (HTE) of Al-Mg is now understood. Using the thermodynamic

  6. Simulation of thermos-solutal convection induced macrosegregation in a Sn-10%Pb alloy benchmark during columnar solidification

    Science.gov (United States)

    Zheng, Y.; Wu, M.; Kharicha, A.; Ludwig, A.

    2016-03-01

    In order to investigate the effect of thermo-solutal convection on the formation of macrosegregation during columnar solidification, simulations with a liquid-columnar two phase model were carried out on a 2D rectangular benchmark of Sn-10%Pb alloy. The solidification direction in the benchmark is unidirectional: (') downwards from top to bottom or (2) upwards from bottom to top. Thermal expansion coefficient, solutal expansion coefficient and liquid diffusion coefficient of the melt are found to be key factors influencing the final macrosegregation. The segregation range and distribution are also strongly influenced by the benchmark configurations, e.g. the solidifying direction (upwards or downwards) and boundary conditions, et al. The global macrosegregation range increases with the velocity magnitude of the melt during the process of solidification.

  7. Bearing Strengths of Some Wrought-aluminum Alloys

    Science.gov (United States)

    Moore, R L; Wescoat, C

    1943-01-01

    Although a number of investigations of the bearing strength of aluminum alloys have been made, the problem remains one of considerable interest to the aircraft industry. For this reason it has seemed advisable to make additional tests of the commonly used aircraft alloys in an effort to establish a better basis for the selection of allowable bearing values. Current design practice does not recognize the effect of edge distance upon bearing strengths, and for this reason edge distance was one of the principal variables considered in this investigation. The increasing emphasis being placed upon permanent set limitations makes it essential that more information on bearing yield phenomena be obtained. The object of this investigation was to determine bearing yield and ultimate strengths of the following aluminum alloy products: 17S-T, 24S-T, Alclad 24S-T, 24S-RT, 52S-0, 52S-1/2H, 52S-H, 53S-T, and 61S-T extrusions. Ratios of these bearing properties to tensile properties were also determined.

  8. Understanding the solidification and microstructure evolution during CSC-MIG welding of Fe–Cr–B-based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sorour, A.A., E-mail: ahmad.sorour@mail.mcgill.ca; Chromik, R.R., E-mail: richard.chromik@mcgill.ca; Gauvin, R., E-mail: raynald.gauvin@mcgill.ca; Jung, I.-H., E-mail: in-ho.jung@mcgill.ca; Brochu, M., E-mail: mathieu.brochu@mcgill.ca

    2013-12-15

    The present is a study of the solidification and microstructure of Fe–28.2%Cr–3.8%B–1.5%Si–1.5%Mn (wt.%) alloy deposited onto a 1020 plain carbon steel substrate using the controlled short-circuit metal inert gas welding process. The as-solidified alloy was a metal matrix composite with a hypereutectic microstructure. Thermodynamic calculation based on the Scheil–Gulliver model showed that a primary (Cr,Fe){sub 2}B phase formed first during solidification, followed by an eutectic formation of the (Cr,Fe){sub 2}B phase and a body-centered cubic Fe-based solid solution matrix, which contained Cr, Mn and Si. Microstructure analysis confirmed the formation of these phases and showed that the shape of the (Cr,Fe){sub 2}B phase was irregular plate. As the welding heat input increased, the weld dilution increased and thus the volume fraction of the (Cr,Fe){sub 2}B plates decreased while other microstructural characteristics were similar. - Highlights: • We deposit Fe–Cr–B-based alloy onto plain carbon steel using the CSC-MIG process. • We model the solidification behavior using thermodynamic calculation. • As deposited alloy consists of (Cr,Fe){sub 2}B plates embedded in Fe-based matrix. • We study the effect of the welding heat input on the microstructure.

  9. Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg–Sn implant alloys prepared by sub-rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chaoyong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Pan, Fusheng, E-mail: fspan@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Zhao, Shuang; Pan, Hucheng; Song, Kai [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Tang, Aitao [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

    2015-09-01

    In this study, biodegradable Mg–Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg–1Sn alloy was almost equiaxed grain, while the Mg–Sn alloys with higher Sn content (Sn ≥ 3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg–Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg{sub 2}Sn phase, and the amount of Mg{sub 2}Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg–Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg–1Sn and Mg–3Sn alloys were promising to be used as biodegradable implants. - Highlights: • Biodegradable Mg–Sn implant alloys were prepared by sub-rapid solidification. • Secondary dendrite arm spacing of alloys decreased with increasing Sn content. • Corrosion rates of alloys increased significantly with increasing Sn content. • Mg–1Sn and Mg–3Sn alloys were harmless to MG63 cells.

  10. Electric pulse treatment of welded joint of aluminum alloy

    Directory of Open Access Journals (Sweden)

    A.A. Mitiaev

    2013-08-01

    Full Text Available Purpose. Explanation of the redistribution effect of residual strengthes after electric pulse treatment of ark welding seam of the aluminum alloy. Methodology. Alloy on the basis of aluminium of АК8М3 type served as the research material. As a result of mechanical treatment of the ingots after alloy crystallization the plates with 10 mm thickness were obtained. After edge preparation the elements, which are being connected were butt welded using the technology of semiautomatic argon arc welding by the electrode with a diameter of 3 mm of AK-5 alloy. Metal structure of the welded joint was examined under the light microscope at a magnification of 200 and under the scanning electronic microscope «JSM-6360 LA». The Rockwell hardness (HRF was used as a strength characteristic of alloy. Hardness measuring of the phase constituents (microhardness was carried out using the device PМТ-3, with the indenter loadings 5 and 10 g. The crystalline structure parameters of alloy (dislocation density, second kind of the crystalline grid distortion and the scale of coherent scattering regions were determined using the methods of X-ray structural analysis. Electric pulse treatment (ET was carried out on the special equipment in the conditions of the DS enterprise using two modes A and В. Findings. On the basis of researches the previously obtained microhardness redistribution effect in the area of welded connection after ET was confirmed. As a result of use of the indicated treatment it was determined not only the reduction of microhardness gradient but also the simultaneous hardening effect in the certain thermal affected areas near the welding seam. During study of chemical composition of phase constituents it was discovered, that the structural changes of alloy as a result of ET first of all are caused by the redistribution of chemical elements, which form the connections themselves. By the nature of the influence the indicated treatment can be

  11. Solidification, growth mechanisms, and associated properties of Al-Si and magnesium lightweight casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hosch, Timothy [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Continually rising energy prices have inspired increased interest in weight reduction in the automotive and aerospace industries, opening the door for the widespread use and development of lightweight structural materials. Chief among these materials are cast Al-Si and magnesium-based alloys. Utilization of Al-Si alloys depends on obtaining a modified fibrous microstructure in lieu of the intrinsic flake structure, a process which is incompletely understood. The local solidification conditions, mechanisms, and tensile properties associated with the flake to fiber growth mode transition in Al-Si eutectic alloys are investigated here using bridgman type gradient-zone directional solidification. Resulting microstructures are examined through quantitative image analysis of two-dimensional sections and observation of deep-etched sections showing three-dimensional microstructural features. The transition was found to occur in two stages: an initial stage dominated by in-plane plate breakup and rod formation within the plane of the plate, and a second stage where the onset of out-of-plane silicon rod growth leads to the formation of an irregular fibrous structure. Several microstructural parameters were investigated in an attempt to quantify this transition, and it was found that the particle aspect ratio is effective in objectively identifying the onset and completion velocity of the flake to fiber transition. The appearance of intricate out-of-plane silicon instability formations was investigated by adapting a perturbed-interface stability analysis to the Al-Si system. Measurements of silicon equilibrium shape particles provided an estimate of the anisotropy of the solid Si/liquid Al-Si system and incorporation of this silicon anisotropy into the model was found to improve prediction of the instability length scale. Magnesium alloys share many of the benefits of Al-Si alloys, with the added benefit of a 1/3 lower density and increased machinability. Magnesium castings

  12. Energy-storage Welding Connection Characteristics of Rapid Solidification AZ91D Mg Alloy Ribbons

    Institute of Scientific and Technical Information of China (English)

    Jinfeng XU; Qiuya ZHAI; Sen YUAN

    2004-01-01

    Energy-storage welding connection characteristics of rapidly solidified AZ91D Mg alloy ribbons with 40~70 μm thickness are investigated using a microtype energy-storage welding machine. The microstructure and performance of the connection joints are analyzed and studied. The research results indicate that energy-storage welding is able to realize the spot welding connection of AZ9lD Mg alloy ribbons. The welding nugget consists of developed α-Mg equiaxed grains with the sizes of 1.2~2.7 μm and intergranular distributed β-Mg17Al12 compounds. The thickness of bond zone is about 4 μm and the solidification microstructure is characterized by the fine equiaxed grains with the sizes of 0.8~1.2μm, and grain boundary has become coarsening. The columnar crystal in HAZ also becomes slightly coarsening and the grain boundary has broadened,however, there is no obvious change in its primitive morphology and crystallographic direction. When welding energy is about 2.0 J, the welding joints with higher shear strength and smaller electrical resistivity are obtained.

  13. Phase separation and rapid solidification of liquid Cu60Fe30Co10 ternary peritectic alloy

    Institute of Scientific and Technical Information of China (English)

    DAI FuPing; CAO ChongDe; WEI BingBo

    2007-01-01

    The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two separated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respectively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) droplets with the same size.

  14. Phase-field modelling of rapid solidification in alloy systems: Spontaneous grain refinement effects

    Science.gov (United States)

    Mullis, A. M.

    2012-07-01

    Phase-field modelling of rapid alloy solidification, in which the rejection of latent heat from the growing solid cannot be ignored, has lagged significantly behind the modelling of conventional casting practises which can be approximated as isothermal. This is in large part due to the fact that if realistic materials properties are adopted the ratio of the thermal to solute diffusivity (the Lewis number) is typically 103 - 104, leading to severe multi-scale problems. However, use of state-of-the-art numerical techniques such as local mesh adaptivity, implicit time-stepping and a non-linear multi-grid solver allow these difficulties to be overcome. Here we describe how the application of this model, formulated in the thin-interface limit, can help to explain the long-standing phenomenon of spontaneous grain refinement in deeply undercooled melts. We find that at intermediate undercoolings the operating point parameter, σ*, may collapse to zero, resulting in the growth of non-dendritic morphologies such as doublons and 'dendritic seaweed'. Further increases in undercooling then lead to the re-establishment of stable dendritic growth. We postulate that remelting of such seaweed structures gives rise to the low undercooling instance of grain refinement observed in alloys.

  15. Phase-field modelling of rapid solidification in alloy systems: Spontaneous grain refinement effects

    International Nuclear Information System (INIS)

    Phase-field modelling of rapid alloy solidification, in which the rejection of latent heat from the growing solid cannot be ignored, has lagged significantly behind the modelling of conventional casting practises which can be approximated as isothermal. This is in large part due to the fact that if realistic materials properties are adopted the ratio of the thermal to solute diffusivity (the Lewis number) is typically 103 - 104, leading to severe multi-scale problems. However, use of state-of-the-art numerical techniques such as local mesh adaptivity, implicit time-stepping and a non-linear multi-grid solver allow these difficulties to be overcome. Here we describe how the application of this model, formulated in the thin-interface limit, can help to explain the long-standing phenomenon of spontaneous grain refinement in deeply undercooled melts. We find that at intermediate undercoolings the operating point parameter, σ*, may collapse to zero, resulting in the growth of non-dendritic morphologies such as doublons and 'dendritic seaweed'. Further increases in undercooling then lead to the re-establishment of stable dendritic growth. We postulate that remelting of such seaweed structures gives rise to the low undercooling instance of grain refinement observed in alloys.

  16. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes

    International Nuclear Information System (INIS)

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg–6%Nd–2%Y–0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd2O3 content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications. - Highlights: • Here we have evaluated the corrosion resistance of a novel Mg alloy (EW62). • Rapid solidification reduces the hydrogen gas evolution and hydrogen embrittlement. • Rapid solidification increases the stress corrosion cracking resistance of EW62. • Improvement is due to enrichment with supersaturated Nd in the external oxide film. • Rapidly solidified and extruded EW62 may serve as a biodegradable medical implant

  17. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Hakimi, O.; Aghion, E. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Goldman, J., E-mail: jgoldman@mtu.edu [Biomedical Engineering Department, Michigan Technological University, Houghton, MI, 49931 (United States)

    2015-06-01

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg–6%Nd–2%Y–0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd{sub 2}O{sub 3} content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications. - Highlights: • Here we have evaluated the corrosion resistance of a novel Mg alloy (EW62). • Rapid solidification reduces the hydrogen gas evolution and hydrogen embrittlement. • Rapid solidification increases the stress corrosion cracking resistance of EW62. • Improvement is due to enrichment with supersaturated Nd in the external oxide film. • Rapidly solidified and extruded EW62 may serve as a biodegradable medical implant.

  18. In situ synchrotron x-ray characterization of microstructure formation in solidification processing of Al-based metallic alloys

    International Nuclear Information System (INIS)

    The microstructure formed during the solidification step has a major influence on the properties of materials processed by major techniques (casting, welding ...). In situ and real-time characterization by synchrotron X-ray imaging is the method of choice to unveil the dynamical formation of the solidification microstructure in metallic alloys, and thus provide precise data for the critical validation of the theoretical predictions that is needed for sound advancement of modeling and numerical simulation. After a description of the experimental procedure used at the European Synchrotron Radiation Facility (ESRF), dynamical phenomena in the formation of the grain structure and dendritic or equiaxed solidification microstructure in Al-based alloys are presented. Beyond fluid flow interaction, earth gravity induces stresses, deformation and fragmentation in the dendritic mush. Settling of dendrite arms and equiaxed grains thus occurs, in particular in the columnar to equiaxed transition. Other types of stresses and strains are caused by the mere formation of the solidification microstructure itself. In white-beam X-ray topography, stresses and strains are manifested by specific contrasts and breaking of the Laue images into several pieces. Finally, quantitative analysis of the grey level in radiographs enables the analysis of solute segregation, which noticeably results in solutal poisoning of growth when equiaxed grains are interacting. (author)

  19. Solidification of Mg-Zn-Y Alloys at 6 GPa Pressure: Nanostructure, Phases Formed, and Their Stability

    Science.gov (United States)

    Zhou, Haitao; Liu, Keming; Zhang, Li; Atrens, Andrej; Yu, Jiuming; Li, Xiaolong

    2016-06-01

    Mg-Zn-Y alloys solidified under high pressure were characterized using XRD, DTA, SEM, and TEM. After solidification at atmospheric pressure, Mg-6Zn-1Y consisted of α-Mg, Mg7Zn3, and Mg3YZn6, while Mg-6Zn-3Y consisted of α-Mg, Mg3Y2Zn3, and Mg3YZn6. After solidification at 6 GPa pressure, both alloys consisted of α-Mg, MgZn, and Mg12YZn. The size and the shape of the second-phase particles formed for atmospheric solidification were significantly different to those formed for solidification at 6 GPa pressure. In Mg-6Zn-1Y, the second-phase size decreased from 300 to 50 nm, and the shape changed from needle like to blocky. In Mg-6Zn-3Y, the size decreased from 100 to 50 nm and the shape changed from short rod like to small and round. After aging at 200 °C for 12 h, the new MgZn phase transformed into the intermediate MgZn2 phase. Increasing the aging time to 24 h caused the intermediate MgZn2 phase to transform into Mg7Zn3 with a size of 50 nm, while the Mg12YZn phase remained unchanged.

  20. Comparison of recrystallization and recrystallization textures in cold-rolled DC and CC AA 5182 aluminum alloys

    International Nuclear Information System (INIS)

    The recrystallization and recrystallization textures in cold-rolled direct chill cast (DC) and continuous cast (CC) AA 5182 aluminum alloys were investigated. The recrystallization behavior of cold-rolled DC and CC AA 5182 aluminum alloys was evaluated by tensile properties. The evolution of recrystallization textures in cold-rolled DC and CC AA 5182 aluminum alloys was determined by X-ray diffraction. The results showed that the recrystallization temperature of cold-rolled DC AA 5182 aluminum alloy was somewhat lower than that of cold-rolled CC AA 5182 aluminum alloy. The resulting recrystallization textures of cold-rolled AA 5182 aluminum alloy were characterized by the strong R orientation and the cube orientation with strong scattering about the rolling direction towards the Goss orientation. CC AA 5182 aluminum alloy showed slightly weaker recrystallization textures than DC AA 5182 aluminum alloy

  1. Effect of Coolant Water Flow Rate on Aluminum Alloys Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Golosov, O.A. [Institute of Nuclear Materials, Zarechny, Sverdlovsk region, 624250 (Russian Federation)

    2011-07-01

    One of the most important factors limiting a life-time of fuel elements in high-flux research reactors are a corrosion rate of fuel cladding material and a formation rate of oxide film. This study presents the results of the corrosion tests with and without irradiation. The aluminum alloys systems Al-Fe-Ni, Al-Fe-Ni-Cu-Mg and Al-Mg-Si-Cu were irradiated in the water flow of a velocity from 1.3 to 14.2m/s at 200 {sup o}C for time within 570 to 2000 hours. (author)

  2. Corrosion fatigue of 2219-T87 aluminum alloy

    Science.gov (United States)

    Mcmillan, V. C.

    1986-01-01

    Corrosion fatigue studies were conducted on bare, chemical conversion coated, and anodized 2219-T87 aluminum alloy. These tests were performed using a rotating beam machine running at a velocity of 2500 rpm. The corrosive environments tested were distilled water, 100 ppm NaCl, and 3.5 percent NaCl. Results were compared to the endurance limit in air. An evaluation of the effect of protective coatings on corrosion fatigue was made by comparing the fatigue properties of specimens with coatings to those without.

  3. Corrosion damage evolution and residual strength of corroded aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Guozhi Lv; Hui Wang; Bomei Si; Yueliang Cheng

    2008-01-01

    The LY12CZ aluminum alloy specimens were eurroded under the conditions of different test temperatures and exposure durations. After corrosion exposure, fatigue tests were performed. Scanning electron microscopy and optical microscope analyses on corrosion damage were carried out. The definition of surface corrosion damage ratio was provided to describe the extent of surface corrosion damage. On the basis of the measured data sets of the corrosion damage ratio, the probabilistic model of corrosion damage evolution was built. The corrosion damage decreased the fatigue life by a factor of about 1.25 to 2.38 and the prediction method of residual strength of the corroded structure was presented.

  4. Sensors Array Technique for Monitoring Aluminum Alloy Spot Welding

    Institute of Scientific and Technical Information of China (English)

    王蕤; 罗震; 单平; 步贤政; 袁书现; 敖三三

    2010-01-01

    In this paper,the sensors array technique is applied to the quality detection of aluminum alloy spot welding.The sensors array has three forms,i.e.,linear magnetic sensors array,annular magnetic sensors array and cross magnetic sensors array.An algorithm based on principal component analysis is proposed to extract the signal eigenvalues.The three types of magnetic sensors array are used in the experiment of monitoring the signal.After the eigenvalues are extracted,they are used to build a relationship with ...

  5. Selection of a mineral binder for the stabilization - solidification of waste containing aluminum metal

    International Nuclear Information System (INIS)

    The dismantling of nuclear facilities produces radioactive waste materials, some of which may contain aluminum metal. In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal becomes corroded, with a continued production of dihydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution

  6. Rheo-diecasting Process for Semi-solid Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel one-step semisolid processing technique, the rheo-diecasting (RDC) process, was developed, which adapts in situ creation of semisolid metal slurry with fine and spherical solid particles followed by direct shaping of the slurry into a near-net shape component using the existing cold chamber diecasting process. The RDC process was applied to process A356 and A380 aluminum alloys. The resulting microstructures and mechanical properties of RDC products under as-cast and various heat treatment conditions were analyzed. The experimental results show that the RDC samples have an extremely low porosity, a fine and uniform microstructure throughout entire casting, and consequently much improved strength and ductility in the as-cast condition. The strength of RDC A356 alloy can be substantially improved under T5 and T6 heat treatments without loss of ductility.

  7. Material and information flows pertaining to aluminum alloy pipe distribution

    Directory of Open Access Journals (Sweden)

    D. Simić

    2013-10-01

    Full Text Available This paper discusses the distribution flow of aluminum (Al alloy pipes, starting with the completion of the manufacturing process and final inspection. The proposed solution considers the use of bar-coded caps produced from recycled polymer materials that are placed on the ends of the tubes in order to achieve protection against potential changes in material properties and preserve the product quality. For the preparation of capped tube bundles for shipment from the manufacturer output storage to the customer input warehouse, a technical solution that enables correct and efficient Al alloy pipe handling is proposed, in terms of safety, security, reliability, financial feasibility and ecological viability, with optimal utilization of transport and storage.

  8. Predictive Capabilities of Multiphysics and Multiscale Models in Modeling Solidification of Steel Ingots and DC Casting of Aluminum

    Science.gov (United States)

    Combeau, Hervé; Založnik, Miha; Bedel, Marie

    2016-06-01

    Prediction of solidification defects, such as macrosegregation and inhomogeneous microstructures, constitutes a key issue for industry. The development of models of casting processes needs to account for several imbricated length scales and different physical phenomena. For example, the kinetics of the growth of microstructures needs to be coupled with the multiphase flow at the process scale. We introduce such a state-of-the-art model and outline its principles. We present the most recent applications of the model to casting of a heavy steel ingot and to direct chill casting of a large Al alloy sheet ingot. Their ability to help in the understanding of complex phenomena, such as the competition between nucleation and growth of grains in the presence of convection of the liquid and of grain motion is shown, and its predictive capabilities are discussed. Key issues for future developments and research are addressed.

  9. A Rare Earth High-iron Aluminum Alloy Cable Company to Settle in Chongqing

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>On September 14,the reporter learnt from the Seminar on Application of New Rare Earth High-iron Aluminum Alloy Cable Technologies for Energy Conservation and Environmental Protection held by Chongqing Electric Industry Association that a rare earth high-iron aluminum alloy cable company with

  10. Contrasting LME in aluminum and nickel alloys, with overtones to SCC

    International Nuclear Information System (INIS)

    The susceptibility of Alloys 400, 600, 200 and 800 to liquid metal embrittlement (LME), hydrogen embrittlement and stress corrosion cracking are in that order (most to least). Correlations exist, too, in the cracking mode, intergranular or transgranular. Accordingly, understanding LME and LME tests have potential uses in alloy development and screening. The use of a quick indentation test for LME is described that worked admirably for aluminum alloys but did not work for nickel-base alloys. The problem is that LME is strain rate sensitive in nickel alloys but not in aluminum alloys. This is believed to be a wetting issue

  11. The solidification and structure of Al-17wt.%Si alloy modified with intermetallic phases containing Ti and Fe

    Directory of Open Access Journals (Sweden)

    J. Piątkowski

    2011-10-01

    Full Text Available The article describes the process of casting and solidification of Al-17wt.%Si alloy that have been modified with composite powdercontaining the intermetallic phases of Ti and Fe. The chemical and phase composition of the applied modifier was described with thefollowingformula:FeAlx–TiAlx–Al2O3. Applying the method of thermal analysis ATD, the characteristic parameters of the solidificationprocess were determined, and exo-and endothermic effects of the modifying powder on the run of the silumin solidification curves wereobserved. By the methods of light, scanning, and X-ray microscopy, the structure of alloy and the chemical composition of the dispersionhardening precipitates were examined. A change in the morphology of Al-Si eutectic from the lamellar to fibrous type was reportedtogether with changes in the form of complex eutectics of an Al-Si-Ti and Al-Si-Fe type and size reduction of primary silicon crystals.

  12. The use of surface modification techniques for the corrosion protection of aluminum and aluminum alloys

    International Nuclear Information System (INIS)

    Surface modification techniques such as ion beam assisted deposition (IBAD) and radio frequency plasma enhanced chemical vapor deposition (PECVD) offer a means to produce surfaces with unique and improved properties. This paper reviews the advantages of the IBAD and PECVD processes and discusses the preparation and pitting corrosion behavior of IBAD modified aluminum surfaces and PECVD coatings on a 7075 aluminum alloy. Pitting potential values for the base materials and for the base materials with silicon nitride IBAD, tantalum oxide IBAD, or PECVD diamond-like carbon coatings were determined in deaerated 0.1M NaCl solutions. The thickness of the modified region ranged from 0.01 to 5.0 microm. All three coatings improved the resistance to pit initiation

  13. Single-aging characteristics of 7055 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Tao; YIN Zhi-min; SHEN Kai; LI Jie; HUANG ji-wu

    2007-01-01

    The microstructures and properties of 7055 aluminum alloy were studied at different single-aging for up to 48 h using hardness test, tensile test, electrical conductivity measurement, XRD and TEM microstructure analysis. The results show that at the early stage of aging, the hardness and strength of the alloy increase rapidly, the peak hardness and strength are approached after 120 ℃ aging for 4 h, then maintained at a high level for a long time. The suitable single-aging treatment of 7055 alloy is 480 ℃, 1 h solution treatment and water quenching, then aging at 120 ℃ for 24 h. Under those condition, the tensile strength, yield strength, elongation and electrical conductivity of the studied alloy are 513 MPa, 462 MPa, 9.5% and 29%(IACS), respectively. During aging, the solid solution decomposes and precipitation occurs. At the early aging stage of 120 ℃, GP zones form and then grow up gradually with increasing ageing time. η' phase forms after ageing for 4 h and η phase starts to occur after 24 h aging.

  14. Retention and release of tritium in aluminum clad, Al-Li alloys

    International Nuclear Information System (INIS)

    Tritium retention in and release from aluminum clad, aluminum-lithium alloys is modeled from experimental and operational data developed during the thirty plus years of tritium production at the Savannah River Site. The model assumes that tritium atoms, formed by the 6Li(n,α)3He reaction, are produced in solid solution in the Al-Li alloy. Because of the low solubility of hydrogen isotopes in aluminum alloys, the irradiated Al-Li rapidly becomes supersaturated in tritium. Newly produced tritium atoms are trapped by lithium atoms to form a lithium tritide. The effective tritium pressure required for trap or tritide stability is the equilibrium decomposition pressure of tritium over a lithium tritide-aluminum mixture. The temperature dependence of tritium release is determined by the permeability of the cladding to tritium and the local equilibrium at the trap sites. This model is used to calculate tritium release from aluminum clad, aluminum-lithium alloys. 9 refs., 3 figs

  15. Comparison of thermal analysis and differential thermal analysis for evaluating solid fraction evolution during solidification of Al-Si alloys

    OpenAIRE

    Fernandez-Calvo, Ana Isabel; Niklas, Andrea; Lacaze, Jacques

    2010-01-01

    Both thermal analysis (TA) and differential thermal analysis (DTA) have been used since long to evaluate latent heat release and solid fraction evolution during solidification of metallic alloys. TA makes use of cooling curves recorded under "natural" cooling while DTA consists in recording the temperature difference between the sample temperature and an inert reference during a controlled cooling, i.e. at imposed constant cooling rate. In both cases, the solid fraction evolution is deduced f...

  16. High-strength and high-RRR Al-Ni alloy for aluminum-stabilized superconductor

    CERN Document Server

    Wada, K; Sakamoto, H; Yamamoto, A; Makida, Y

    2000-01-01

    The precipitation type aluminum alloys have excellent performance as the increasing rate in electric resistivity with additives in the precipitation state is considerably low, compared to that of the aluminum alloy with additives in the solid-solution state. It is possible to enhance the mechanical strength without remarkable degradation in residual resistivity ratio (RRR) by increasing content of selected additive elements. Nickel is the suitable additive element because it has very low solubility in aluminum and low increasing rate in electric resistivity, and furthermore, nickel and aluminum form intermetallic compounds which effectively resist the motion of dislocations. First, Al-0.1wt%Ni alloy was developed for the ATLAS thin superconducting solenoid. This alloy achieved high yield strength of 79 MPa (R.T.) and 117 MPa (4.2 K) with high RRR of 490 after cold working of 21% in area reduction. These highly balanced properties could not be achieved with previously developed solid-solution aluminum alloys. ...

  17. Interfacial study of semi-solid aluminum alloy and stainless steel sheathed extrusion

    Institute of Scientific and Technical Information of China (English)

    LIU Hong-wei; GUO Cheng; LIU Xu-feng; SHAO Guang-jie

    2006-01-01

    Using sheathed extrusion technique, the bonding and forming of semi solid aluminum alloy with stainless steel sheath are successfully realized. The relationship between the interfacial shear strength and the solid fraction of semi solid aluminum alloy at different extrusion ratios is analyzed; the interfacial and fracture structure of the sheath material are studied by optical microscopy(OM) and scanning electric microscopy(SEM). The result shows that interfacial shear strength increases with the increase of extrusion ratio, the maximum value of the interfacial shear strength is obtained when solid fraction of aluminum alloy is 30%,solid phase and liquid phase of the semi solid aluminum alloy are bonded with stainless steel by turns along the interface, and the aluminum alloy can not be peeled from the stainless steel completely, which means nicer bonding occurs at the interface.

  18. Flexural-torsional buckling behavior of aluminum alloy beams

    Institute of Scientific and Technical Information of China (English)

    Xiaonong GUO; Zhe XIONG; Zuyan SHEN

    2015-01-01

    This paper presents an investigation on the flexural-torsional buckling behavior of aluminum alloy beams (AAB). First, based on the tests of 14 aluminum alloy beams under concentrated loads, the failure pattern, load- deformation curves, bearing capacity and flexural-torsional buckling factor are studied. It is found that all the beam specimens collapsed in the flexuml-torsional buckling with excessive deformation pattern. Moreover, the span, loading location and slenderness ratio influence the flexural-torsional buckling capacity of beams significantly. Secondly, besides the experiments, a finite element method (FEM) analysis on the flexural-torsional buckling behavior of AAB is also conducted. The main parameters in the FEM analysis are initial imperfection, material property, cross-section and loading scheme. According to the analytical results, it is indicated that the FEM is reasonable to capture mechanical behavior of AAB. Finally, on the basis of the experimental and analytical results, theoretical formulae to estimate the flexural- torsional buckling capacity of AAB are proposed, which could improve the application of present codes for AAB.

  19. Stress corrosion cracking susceptibility of 7A52 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jun-jun; WANG Wei-xin; CAI Zhi-hai; ZHANG Ping

    2006-01-01

    The stress corrosion sensitivity of 7A52 aluminum alloy was investigated in the artificial sea water through slow stain rate test(SSRT). The stress corrosion cracking(SCC) susceptibility was estimated with the loss of elongation and stress corrosion sensitivity index. The results show that the susceptibility of 7A52 aluminum alloy is always high when the strain rate is in the range of 10-5-10-7s-1. It reaches the maximum at the strain rate of 8.7×10-7s-1, and the sensitivity index reaches 0.346. The characteristics of stress corrosion can be observed clearly on the fracture of tensile specimen. The process of SCC is depicted according to the fracture morphology. The SCC initiates at the edge of the specimen. Then the SCC grows rapidly because of the anode dissolving and stress concentration. When the area of specimen cannot support the tensile stress, it ruptures suddenly. The secondary cracks and quasi-cleavage surface can be found on the fracture morphology.susceptibility

  20. and Carbon Fiber Reinforced 2024 Aluminum Alloy Composites

    Science.gov (United States)

    Kaczmar, Jacek W.; Naplocha, Krzysztof; Morgiel, Jerzy

    2014-08-01

    The microstructure and mechanical properties of 2024 aluminum alloy composite materials strengthened with Al2O3 Saffil fibers or together with addition of carbon fibers were investigated. The fibers were stabilized in the preform with silica binder strengthened by further heat treatment. The preforms with 80-90% porosity were infiltrated by direct squeeze casting method. The microstructure of the as-cast specimens consisted mainly of α-dendrites with intermetallic compounds precipitated at their boundaries. The homogenization treatment of the composite materials substituted silica binder with a mixture of the Θ phase and silicon precipitates distributed in the remnants of SiO2 amorphous phase. Outside of this area at the binder/matrix interface, fine MgO precipitates were also present. At surface of C fibers, a small amount of fine Al3C4 carbides were formed. During pressure infiltration of preforms containing carbon fibers under oxygen carrying atmosphere, C fibers can burn releasing gasses and causing cracks initiated by thermal stress. The examination of tensile and bending strength showed that reinforcing of aluminum matrix with 10-20% fibers improved investigated properties in the entire temperature range. The largest increase in relation to unreinforced alloy was observed for composite materials examined at the temperature of 300 °C. Substituting Al2O3 Saffil fibers with carbon fibers leads to better wear resistance at dry condition with no relevant effect on strength properties.

  1. The effect of adding boron in solidification microstructure of dilute iron-carbon alloy as assessed by phase-field modeling

    Directory of Open Access Journals (Sweden)

    Henrique Silva Furtado

    2011-01-01

    Full Text Available Alloying element like boron, even in small addition, is well known to improve hardenability of steels. Its application can improve mechanical properties of steels and reduce alloying costs. Despite these benefits is not easy to cast boron steels, mainly in dynamical solidification process like continuous casting, due to their crack susceptibility1,2. The strategy of using Phase-Field simulation of the solidification process is based on its proved capacity of predicting realistic microstructure that emerge during solidification under conditions even far from equilibrium3-5. Base on this, some comparative simulations were performed using a three component dilute alloy in a two dimensional domain under unconstrained (isothermal and constrained (directional solidification. Simulation results suggested two fragile mechanisms: one related to a deep dendritic primary arms space and other due to the remelting of this region at low temperature. Both resulted mainly from the high boron segregation in interdendritic regions.

  2. Investigation of Corrosion Behavior Of 6013 Aluminum Alloys For Artificial Aged Microwave Furnace

    Directory of Open Access Journals (Sweden)

    Muzaffer Erdoğan

    2014-01-01

    Full Text Available Low density and high strength aluminum alloys can be achieved today is a type of an alloy. These alloys are more resistant, particularly the aging process is the precipitate formed. In this study, increased strength 6013 aluminum alloy in a microwave furnace yaşlandırarak artificial. Volume samples in a microwave oven aging method and aging has provided a homogeneous way.6013 aluminum alloys, pure argon gas atmosphere in a microwave furnace hardness after being subjected to artificial aging process analysis, the internal structure (optical microscope, SEM, characterization of the studied. Aging of the phases, the presence server in the XRD of the samples was determined by curves. Corrosion of artificial aged samples has been analyzed by the internal structure of the phases present. Depending on the time of artificial aging of aluminum alloy 6013 samples in a microwave furnace in the mechanical properties of the sediment affected the corrosion resistance values.

  3. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    Science.gov (United States)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-06-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  4. Thermal Decoating of Aerospace Aluminum Alloys for Aircraft Recycling

    Science.gov (United States)

    Muñiz Lerma, Jose Alberto; Jung, In-Ho; Brochu, Mathieu

    2016-03-01

    Recycling of aircraft aluminum alloys can be complex due to the presence of their corrosion protection coating that includes inorganic compounds containing Cr(VI). In this study, the characterization and thermal degradation behavior of the coating on aluminum substrates coming from an aircraft destined for recycling are presented. Elements such as Sr, Cr, Si, Ba, Ti, S, C, and O were found in three different layers by EDS elemental mapping corresponding to SrCrO4, Rutile-TiO2, SiO2, and BaSO4 with an overall particle size D 50 = 1.96 µm. The thermal degradation profile analyzed by TGA showed four different stages. The temperature of complete degradation at the fourth stage occurred at 753.15 K (480 °C) at lower heating rates. At higher heating rates and holding an isotherm at the same temperature, the residence time to fully decompose the aircraft coating has been estimated as 4.0 ± 0.2 minutes. The activation energy calculated by the Flynn-Wall-Ozawa and the modified Coats-Redfern methods for multiple fraction of decomposition showed a non-constant behavior indicating the complexity of the reaction. Finally, the concentration of Cr(VI) released to the environment during thermal decoating was obtained by UV-Vis spectroscopy. It was found that 2.6 ± 0.1 µg of Cr(VI)/mm2 of aluminum substrate could be released unless adequate particle controls are used.

  5. Fatigue Resistance of Liquid-assisted Self-repairing Aluminum Alloys Reinforced with Shape Memory Alloys

    Science.gov (United States)

    Wright, M. Clara; Manuel, Michele; Wallace, Terryl

    2013-01-01

    A self-repairing aluminum-based composite system has been developed using a liquid-assisted healing theory in conjunction with the shape memory effect of wire reinforcements. The metal-metal composite was thermodynamically designed to have a matrix with a relatively even dispersion of a low-melting eutectic phase, allowing for repair of cracks at a predetermined temperature. Additionally, shape memory alloy (SMA) wire reinforcements were used within the composite to provide crack closure. Investigators focused the research on fatigue cracks propagating through the matrix in order to show a proof-of-concept Shape Memory Alloy Self-Healing (SMASH) technology for aeronautical applications.

  6. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  7. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    Science.gov (United States)

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  8. Real time observation on the solidification of strontium-modified zinc–aluminum–silicon alloys by synchrotron microradiography

    International Nuclear Information System (INIS)

    Highlights: • The real time solidification of strontium-modified Zn–Al–Si alloys are studied. • The primary silicon has an increased growth rate with the addition of strontium. • Some eutectics are observed to nucleate away from the primary silicon. • The solidification sequence of different eutectics are described. - Abstract: The effect of strontium on the solidification of zinc–aluminum–silicon alloys has been studied. The microstructures of Zn–27%Al–3%Si alloys with different concentrations of strontium were investigated by optical microscope. The solidification processes of unmodified and strontium-modified Zn–27%Al–3%Si alloys were directly observed through the third generation Shanghai Synchrotron Radiation Facility. It was found that the nucleation of primary silicon reduced by additions of strontium, while the precipitation of eutectic silicon was promoted. Imaging experiment results showed that the precipitation temperature of primary silicon was greatly depressed (about 20 °C) while the precipitation temperature of α-Al increased (about 7 °C) by the addition of strontium. The suppressed nucleation resulted in an increased growth rate of primary silicon. The morphology of primary silicon crystals changed from a highly faceted to less faceted and more dendritic after modification, which might be caused by the higher growth rate, poisoning the layer growth mechanism and the Vertex-Linked of octahedral growth unit. Meanwhile, with the increase of cooling rate, the primary silicon became much more branched in the strontium-modified alloys. The needle-shaped eutectic silicon did not nucleate at the surface of the primary silicon in the unmodified alloys, but the coral-like eutectic silicon was found readily nucleating at the surface of primary silicon in the modified alloys due to the addition of strontium. After image processing, some eutectics were observed to nucleate overlapping with pre-existing α-Al or form in the remaining

  9. Surface properties of aluminum alloy as material for ultrahigh vacuum

    International Nuclear Information System (INIS)

    The characteristics of aluminum alloy (2017 alloy) for the vacuum chambers of TRISTAN were studied. Machining, electric discharge machining and chemical polishing were made successively on the samples of the 2017 alloy. The observation of surface state, the analysis of surface composition and high temperature desorption experiment were performed. The measurement of surface roughness with a probe, the observation with a scanning electron microscope (SEM), and the measurement of surface roughness factor (SRF) were carried out as the study of the surface state. The analysis of surface composition was made by the Auger electron spectrometry. It was found that the surfaces of samples treated by discharge machining were rough and have thick oxide layer. When chemical polishing was applied to these samples, the surfaces became smooth, and the oxide layer became thin. By heating the samples to raise the temperature, the desorption of H2O, CO and CO2 was caused. The amount of desorption was in close relation with the SRF. (Kato, T.)

  10. Corrosion of aluminum alloys in ocean thermal energy conversion seawaters

    International Nuclear Information System (INIS)

    Aluminum alloys 5052, 3004, and Alclad 3003 and 3004 were exposed to flowing seawater at 2.44 m/s (8 fps) at the Seacoast Test Facility on Hawaii. One year data for warm surface water and three mouth data for cold water from 600 m depth are reported for free fouling, chlorinated and sponge ball cleaned conditions. All alloys pit in deep seawater, but show no pitting in warm surface water. Uniform corrosion in the warm water is initially rapid, but after 25 to 30 days the rate becomes slower and extrapolated 30 year material losses are in the 125 to 215 μm range. Chlorination at a level of 0.05 ppm for one hour per day has only a minor effect on corrosion rates, while sponge ball cleaning leads to erosion-corrosion of the Alclad surfaces and has no effect on alloy 5052. The need for additional testing in tropical seawater is discussed, as is the need for an improved understanding of the formation of inorganic scale films, their properties, and their effect on corrosion rates and heat transfer

  11. Anisotropic Effects on Constitutive Model Parameters of Aluminum Alloys

    Science.gov (United States)

    Brar, Nachhatter; Joshi, Vasant

    2011-06-01

    Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. The model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloys. Johnson-Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulations go well beyond minor parameter tweaking and experimental results are drastically different it is important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy we performed quasi-static and high strain rate tensile tests on specimens fabricated in the longitudinal, transverse, and thickness directions of 1' thick Al7075-T651 plate. Flow stresses at a strain rate of ~1100/s in the longitudinal and transverse direction are similar around 670MPa and decreases to 620 MPa in the thickness direction. These data are lower than the flow stress of 760 MPa measured in Al7075-T651 bar stock.

  12. Characterization of Rapidly Solidified Al-27 Si Hypereutectic Alloy: Effect of Solidification Condition

    Science.gov (United States)

    Cai, Zhiyong; Wang, Richu; Zhang, Chun; Peng, Chaoqun; Xie, Lichuan; Wang, Linqian

    2015-03-01

    Rapidly solidified Al-27wt.%Si hypereutectic alloy was fabricated by gas atomization, and its characterization as a function of particle size was investigated. A relationship between the particle size and solidification condition was established to understand the microstructural characteristics. While the irregular primary Si phase transformed to quasi-spherical shape, and its size decreased gradually with the particle size, the primary Si morphology similar to that in ingot metallurgy sample was found from the deep-etched images. In the fine powder, the eutectic Si phase formed a network structure densely distributed in the matrix, while a tangled dendritic formed at the surface. From the distribution of the Si phase, it is suggested that the microstructure inhomogeneity increased as the particle size decreases. The structural distortion of the Al matrix was observed from x-ray diffraction patterns and differential scanning calorimetry curves. From the calculated results, an undercooling of 33 K (or interface velocity of 8 mm/s) was sufficient to suppress the primary Si to less than 2 μm in the present composition. The microhardness increased significantly while the particle size decreases. The microstructure and properties of the bulk material consolidated by hot pressing of the powders obtained were also conducted.

  13. Interfacial strength and structure of joining between 2024 aluminum alloy and SiCp/2024 Al composite in semi-solid state

    International Nuclear Information System (INIS)

    Highlights: • Joined 2024 aluminum alloy and SiCp/2024 composite in semi-solid status. • The shear strength of interface had reached to that of SiCp/2024 Al composite. • The mechanism of joining in semi-solid was discussed in this paper. - Abstract: Semi-solid joining of 2024 aluminum alloy and SiCp/2024 Al composite was investigated based on the shear strength and microstructure of interface. An as-extruded 2024 aluminum alloy was chosen in this study for its fine crystal grain and higher strain energy, which was beneficial to the preparation of semi-solid billet. Then recrystallisation and partial melting method (RAP) was carried out to prepare semi-solid billet of 2024 aluminum alloy. Then the semi-solid 2024 aluminum alloy was joined with the SiCp/2024 Al composite, which was also in the semi-solid state, at/under different temperatures/pressures. Shear test was performed to measure the interfacial strength. Scanning electron microscope (SEM) was used to observe the microstructure of interface. The results showed that the shear strength of interface had reached to that of SiCp/2024 Al composite. The shear strength increased as the applied pressure increasing, and had a close relationship with temperature. The mechanism of semi-solid joining with pressure was that the mixture of two kinds of base materials, accompanying with the diffusion of atom at high temperatures. It should be pointed out that the microstructure of interface was much finer than that of the substrate, due to the nucleation promotion of SiC particle in the solidification process

  14. Modeling on the Solidification of 1J51 Fe-Ni-Based Alloy Ingot Under Vacuum Conditions

    Science.gov (United States)

    Zhang, Lifeng; Gao, Chen; Li, Chongwei; Peng, Jie

    2014-07-01

    In this article, a numerical simulation model on the solidification of 1J51 Fe-Ni based alloy under vacuum conditions was established using ProCAST software (ESI Group, Paris, France). The calculated temperature profiles of the mold and the solidification profile of the ingot were compared with the measurement, showing a reasonable agreement. The validated model was then used to study the effects of the insulation condition, filling rate, and maximum filling fraction on the solidification state and porosity distribution of the ingot. It was indicated that the shrinkage cavity position of ingot with zirconia fiber was lower than that without zirconia fiber, and the likelihood of centerline shrinkage porosity was independent of the insulation method. The position of macroporosity varied little when the filling rate was from 2.17 kg/s to 5.17 kg/s, while serious solidification defects occurred in the body of ingot when the filling rate was lower than 4.17 kg/s. Increasing the maximum filling fraction had a positive impact on the rise of shrinkage cavity position, but it was hardly advisable because the metal yield decreased with the increase of the maximum filling fraction. Considering the above parameters discussed in this article, it was proposed to remove the zirconia fiber layer for the industrial practice.

  15. Rapid Directional Solidification with Ultra-High Temperature Gradient and Cellular Spacing Selection of Cu-Mn Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The detailed laser surface remelting experiments of Cu-31.4 wt pct Mn and Cu-26.6 wt pct Mn alloys on a 5 kW CO2laser were carried out to study the effects of processing parameters (scanning velocity, output power of laser) on the growthdirection of microstructure in the molten pool and cellular spacing selection under the condition of ultra-high temperaturegradient and rapid directional solidification. The experimental results show that the growth direction of microstructure isstrongly affected by laser processing parameters. The ultra-high temperature gradient directional solidification can be realizedon the surface of samples during laser surface remelting by controlling laser processing parameters, the temperature gradientand growth velocity can reach 106 K/m and 24.1 mm/s, respectively, and the solidification microstructure in the center ofthe molten pool grows along the laser beam scanning direction. There exists a distribution range of cellular spacings underthe laser rapid solidification conditions, and the average spacing decreases with increasing of growth rate. The maximum,λ minimum, λmin, and average primary spacing,λ, as functions of growth rate, Vb, can be given by, λ =12.54V b-0.61,λmin=4.47 Vb-0.52, λ=9.09Vb-0.62, respectively. The experimental results are compared with the current Hunt-Lu model forrapid cellular/dendritic growth, and a good agreement is found.

  16. Microstructural features of intergranular brittle fracture and cold cracking in high strength aluminum alloys

    NARCIS (Netherlands)

    Lalpoor, M.; Eskin, D. G.; ten Brink, Gert; Katgerman, L.

    2010-01-01

    Intergranular brittle fracture has been mainly observed and reported in steel alloys and precipitation hardened At-alloys where intergranular precipitates cover a major fraction of the grain boundary area. 7xxx series aluminum alloys suffer from this problem in the as-cast condition when brittle int

  17. Divorced eutectic in a HPDC magnesium-aluminum alloy

    International Nuclear Information System (INIS)

    The morphology of the eutectic in a thin-wall high pressure die cast (HPDC) U-shape AM60 magnesium box was investigated by light microscope, SEM, TEM and EPMA. The extremely fast cooling rate taking place in the solidification process produces a highly segregated zone near the boundaries of small grains and a fine distribution of β particles, which is typical of a completely divorced eutectic. It was shown that the segregated zone is coherent with the primary α-Mg grain core even if the increased aluminium content produces a deformation of the hexagonal crystal lattice, which was estimated through diffraction patterns (SADP). The variation of the alloying elements content through the grain boundaries was shown by means of EPMA line scanning. The β particle composition was quantitatively investigated and the results show that, in comparison with the equilibrium phase diagram, the non-equilibrium phase boundary of the Mg17Al12 region is moved some percent towards the lower aluminium content, at the high cooling rate that occurs in high pressure die castings. The cubic structure of the β phase was revealed by diffraction pattern. The presence of small Al-Mn particles both inside the grain and in the boundary region was also put in evidence by TEM

  18. A modified Johnson–Cook model of dynamic tensile behaviors for 7075-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: • The dynamic mechanical behaviors at various strain rates were measured. • The strain rate hardening effect of 7075-T6 aluminum alloy is significant. • A new Johnson–Cook constitutive model of 7075-T6 aluminum alloy was obtained. • Numerical simulations of tensile tests at different rates were conducted. • Accuracy of the modified Johnson–Cook constitutive equation was proved. - Abstract: The dynamic mechanical behaviors of 7075-T6 aluminum alloy at various strain rates were measured by dynamic tensile tests using the electronic universal testing machine, high velocity testing system and split Hopkinson tensile bar (SHTB). Stress–strain curves at different rates were obtained. The results show that the strain rate hardening effect of 7075-T6 aluminum alloy is significant. By modifying the strain rate hardening term in the Johnson–Cook constitutive model, a new Johnson–Cook (JC) constitutive model of 7075-T6 aluminum alloy was obtained. The improved Johnson–Cook model matched the experiment results very well. With the Johnson–Cook constitutive model, numerical simulations of tensile tests at different rates for 7075-T6 aluminum alloy were conducted. According to tensile loading and stress–strain relation of 7075-T6 aluminum alloy, calculation results were compared with experimental results. Accuracy of the modified Johnson–Cook constitutive equation was further proved

  19. A modified Johnson–Cook model of dynamic tensile behaviors for 7075-T6 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ding-Ni, E-mail: siping4840@126.com [The College of Information, Mechanical and Electrical Engineering, Shanghai Normal University, Shanghai 200234 (China); Shangguan, Qian-Qian [The College of Information, Mechanical and Electrical Engineering, Shanghai Normal University, Shanghai 200234 (China); Xie, Can-Jun [Commercial Aircraft Corporation of China, Ltd., Shanghai 200120 (China); Liu, Fu [Shanghai Aircraft Design and Research Institute of COMAC, Shanghai 201210 (China)

    2015-01-15

    Highlights: • The dynamic mechanical behaviors at various strain rates were measured. • The strain rate hardening effect of 7075-T6 aluminum alloy is significant. • A new Johnson–Cook constitutive model of 7075-T6 aluminum alloy was obtained. • Numerical simulations of tensile tests at different rates were conducted. • Accuracy of the modified Johnson–Cook constitutive equation was proved. - Abstract: The dynamic mechanical behaviors of 7075-T6 aluminum alloy at various strain rates were measured by dynamic tensile tests using the electronic universal testing machine, high velocity testing system and split Hopkinson tensile bar (SHTB). Stress–strain curves at different rates were obtained. The results show that the strain rate hardening effect of 7075-T6 aluminum alloy is significant. By modifying the strain rate hardening term in the Johnson–Cook constitutive model, a new Johnson–Cook (JC) constitutive model of 7075-T6 aluminum alloy was obtained. The improved Johnson–Cook model matched the experiment results very well. With the Johnson–Cook constitutive model, numerical simulations of tensile tests at different rates for 7075-T6 aluminum alloy were conducted. According to tensile loading and stress–strain relation of 7075-T6 aluminum alloy, calculation results were compared with experimental results. Accuracy of the modified Johnson–Cook constitutive equation was further proved.

  20. Solidification process and effect of thermal treatments on Ni–Co–Mn–Sn metamagnetic shape memory alloys

    International Nuclear Information System (INIS)

    The solidification process of three metamagnetic Ni–Co–Mn–Sn alloys has been investigated by DTA and DSC calorimetry, X-ray diffraction, optical and electron microscopy. The as-cast microstructures are composed of three phases: austenite L21/6-layered martensite, D03 phase and γ phase (disordered fcc). Subsequent annealing treatments at 900 °C completely dissolve the D03 phase in the three alloys and also the γ phase in alloys with low Co content (6.4 and 7.2 at.%). However, for 9 at.% Co the stability of γ-phase extends to temperatures close to the melting point and becomes very sensitive to the Mn and Sn content. No traces of the B2–L21 order–disorder transition have been obtained in the alloys investigated. The multiphase solidification can be interpreted as a peritectic process where D03 is the primary solidified phase with dendritic growth, followed by the peritectic reaction of this phase with the residual liquid to form the austenite L21, whereas the γ-phase precipitates from the austenite L21 upon further cooling

  1. The effects of rapid solidification on microstructure and hydrogen sorption properties of binary BCC Ti–V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Suwarno, S., E-mail: S.Suwarno@uu.nl [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Solberg, J.K. [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Maehlen, J.P. [Institute for Energy Technology, P.O. Box 40, NO-2027, Kjeller (Norway); Krogh, B. [Statoil ASA Research Centre, Rotvoll, NO-7005, Trondheim (Norway); Yartys, V.A. [Department of Materials Science and Engineering, NTNU, NO-7491, Trondheim (Norway); Institute for Energy Technology, P.O. Box 40, NO-2027, Kjeller (Norway)

    2014-01-05

    Highlights: • Effect of quenching rate and Ti/V ratio on the phase-structural composition. • Grain size refinement in the rapidly solidified Ti–V alloys. • Hydrogen storage properties of rapidly solidified binary Ti–V. • Mechanism of phase transformations in the hydrides of the RS Ti–V alloys. -- Abstract: The main purpose of the present work was to study the effect of rapid solidification (RS) on the microstructure and hydrogen storage properties of body centred cubic (BCC) Ti rich Ti–V alloys (Ti{sub 1−x}V{sub x}, x = 0.1–0.3). Ribbons were prepared by melt spinning at spinner rotation velocities of 1000–3000 rpm. Ribbon morphology and microstructure were found to depend on the vanadium content and spinner velocity. For Ti{sub 0.8}V{sub 0.2}, the relation between the ribbon thickness and velocity can be expressed as a power law function, indicating that, during solidification of the Ti–V ribbons, heat transfer at the interface between spinner and ribbon controls the heat extraction. Temperature desorption spectroscopy (TDS) and in situ synchrotron (SR-XRD) studies of the RS alloys showed that hydrogen desorption from the RS alloy hydrides occurred at lower temperatures than from the as cast alloys. RS caused a microscale chemical element separation in the alloys, which depends on the vanadium content and the spinner velocity. In addition, ribbon recalescence was observed to cause nanoscale chemical redistribution trough spinodal decomposition. These two last features were proposed to be the reasons for the observed thermal destabilisation.

  2. Effect of aging on the corrosion of aluminum alloy 6061

    International Nuclear Information System (INIS)

    Not only alloying additions may affect the corrosion resistance of aluminum alloys, but also practices that result in a nonuniform microstructure may introduce susceptibility to some forms of corrosion, especially if the microstructural effect is localized. This work was intended to study the effect of aging time at 225, 185 and 140 degree C and the effect of constant aging time ( 24 hrs ) in the temperature range 100 - 450 degree C as well as the influence of the solution ph on the corrosion characteristics of 6061 aluminum alloy, (Al-Mg-Si alloy) containing 0.22 wt% Cu. The investigation was performed by standard immersion corrosion test according to the British Standard BS 11846 method B and by applying potentiodynamic polarization technique in neutral deaerated 0.5 % M NaCl solution as well as in alkaline NaOH solution (ph = 10). The susceptibility to corrosion and the dominant corrosion type was evaluated by examination of transverse cross sections of corroded samples after the immersion test and examination of the corroded surfaces after potentiodynamic polarization using optical microscope. Analysis of the polarization curves was used to determine the effect of different aging parameters on corrosion characteristics such as the corrosion current density I (corr), the corrosion potential E (corr), the cathodic current densities and the passivation behavior.Results of the immersion test showed susceptibility to intergranular corrosion in the under aged tempers while pitting was the dominant corrosion mode for the over aged tempers after aging at 225 and 185 degree C.Analysis of the potentiodynamic polarization curves showed similar dependence of I (corr) and cathodic current densities on the aging treatment in the neutral 0.5 %M NaCl solution and in the alkaline NaOH solution. It was observed that E(corr) values in the NaCl solution were shifted in the more noble direction for the specimens aged before peak aging while it decreased again with aging time for

  3. Standard guide for conducting exfoliation corrosion tests in aluminum alloys

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1992-01-01

    1.1 This guide differs from the usual ASTM standard in that it does not address a specific test. Rather, it is an introductory guide for new users of other standard exfoliation test methods, (see Terminology G 15 for definition of exfoliation). 1.2 This guide covers aspects of specimen preparation, exposure, inspection, and evaluation for conducting exfoliation tests on aluminum alloys in both laboratory accelerated environments and in natural, outdoor atmospheres. The intent is to clarify any gaps in existent test methods. 1.3 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  4. Compressive formability of 7075 aluminum alloy rings under hydrostatic pressure

    Institute of Scientific and Technical Information of China (English)

    LIU Gang; WANG Li-liang; YUAN Shi-jian; WANG Zhong-ren

    2006-01-01

    In order to investigate the influence of hydrostatic pressure on compression limit of the ring, numerical simulation and experimental research were carried out. The effect of hydrostatic pressure on the deformation of aluminum alloy 7075 ring was obtained by numerical simulation. The die set for compressing ring under high hydrostatic pressure was designed and manufactured. Experimental results show that the compression limit increases linearly as the hydrostatic pressure increases in a certain range. At 100 MPa the maximum compressive strain is increased by 32.42%. At strain limit, the cracks initiate from the corner of the outer wall to the middle of the inner wall along the direction of the maximum shear stress.

  5. Amorphous coatings deposited on aluminum alloy by plasma electrolytic oxidation

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2005-01-01

    Amorphous [Al-Si-O] coatings were deposited on aluminum alloy by plasma electrolytic oxidation (PEO). The process parameters, composition, micrograph, and mechanical property of PEO amorphous coatings were investigated. It is found that the growth rate of PEO coatings reaches 4.44 μm/min if the current density is 0.9 mA/mm2. XRD results show that the PEO coatings are amorphous in the current density range of 0.3 - 0.9mA/mm2. EDS results show that the coatings are composed of O, Si and Al elements. SEM results show that the coatings are porous. Nano indentation results show that the hardness of the coatings is about 3 - 4 times of that of the substrate, while the elastic modulus is about the same with the substrate. Furthermore, a formation mechanism of amorphous PEO coatings was proposed.

  6. High cycle fatigue characteristics of 2124-T851 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LI Xue; YIN Zhimin; NIE Bo; ZHONG Li; PAN Qinglin; JIANG Feng

    2007-01-01

    The fatigue crack growth rate, fracture toughness and fatigue S-N curve of 2124-T851 aluminum alloy at high cycle fatigue condition were measured and fatigue fracture process and fractography were studied using optical microscopy (OM), X-ray diffraction (XRD) technique, trans-mission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that at room tempera-ture and R = 0.1 conditions, the characteristics of fatigue fracture could be observed. Under those conditions, the fatigue strength and the fracture toughness of a 2124-T851 thick plate is 243 MPa and 29.64 MPa·m1/2,respectively.At high cycle fatigue condition, the higher the stress amplitude,the wider the space between fatigue striations, the faster the rate of fatigue crack developing and going into the intermittent fracture area, and the greater the ratio between the intermittent fracture area and the whole fracture area.

  7. Elevated temperature crack growth in advanced powder metallurgy aluminum alloys

    Science.gov (United States)

    Porr, William C., Jr.; Gangloff, Richard P.

    1990-01-01

    Rapidly solidified Al-Fe-V-Si powder metallurgy alloy FVS0812 is among the most promising of the elevated temperature aluminum alloys developed in recent years. The ultra fine grain size and high volume fraction of thermally stable dispersoids enable the alloy to maintain tensile properties at elevated temperatures. In contrast, this alloy displays complex and potentially deleterious damage tolerant and time dependent fracture behavior that varies with temperature. J-Integral fracture mechanics were used to determine fracture toughness (K sub IC) and crack growth resistance (tearing modulus, T) of extruded FVS0812 as a function of temperature. The alloy exhibits high fracture properties at room temperature when tested in the LT orientation, due to extensive delamination of prior ribbon particle boundaries perpendicular to the crack front. Delamination results in a loss of through thickness constraint along the crack front, raising the critical stress intensity necessary for precrack initiation. The fracture toughness and tensile ductility of this alloy decrease with increasing temperature, with minima observed at 200 C. This behavior results from minima in the intrinsic toughness of the material, due to dynamic strain aging, and in the extent of prior particle boundary delaminations. At 200 C FVS0812 fails at K levels that are insufficient to cause through thickness delamination. As temperature increases beyond the minimum, strain aging is reduced and delamination returns. For the TL orientation, K (sub IC) decreased and T increased slightly with increasing temperature from 25 to 316 C. Fracture in the TL orientation is governed by prior particle boundary toughness; increased strain localization at these boundaries may result in lower toughness with increasing temperature. Preliminary results demonstrate a complex effect of loading rate on K (sub IC) and T at 175 C, and indicate that the combined effects of time dependent deformation, environment, and strain aging

  8. Application of a criterion for cold cracking to casting high strength aluminum alloys

    OpenAIRE

    Lalpoor, M; Eskin, D G; Fjaer, H.G.; Ten Cate, A.; Ontijt, N.; Katgerman, L.

    2010-01-01

    Direct chill (DC) casting of high strength 7xxx series aluminium alloys is difficult mainly due to solidification cracking (hot cracks) and solid state cracking (cold cracks). Poor thermal properties along with extreme brittleness in the as-cast condition make DC-casting of such alloys a challenging process. Therefore, a criterion that can predict the catastrophic failure and cold cracking of the ingots would be highly beneficial to the aluminium industry. The already established criteria are...

  9. Small-crack effects in high-strength aluminum alloys

    Science.gov (United States)

    Newman, J. C., Jr.; Wu, X. R.; Venneri, S. L.; Li, C. G.

    1994-01-01

    The National Aeronautics and Space Administration and the Chinese Aeronautical Establishment participated in a Fatigue and Fracture Mechanics Cooperative Program. The program objectives were to identify and characterize crack initiation and growth of small cracks (10 microns to 2 mm long) in commonly used US and PRC aluminum alloys, to improve fracture mechanics analyses of surface- and corner-crack configurations, and to develop improved life-prediction methods. Fatigue and small-crack tests were performed on single-edgenotch tension (SENT) specimens and large-crack tests were conducted on center-crack tension specimens for constant-amplitude (stress ratios of -1, 0, and 0.5) and Mini-TWIST spectrum loading. The plastic replica method was used to monitor the initiation and growth of small fatigue cracks at the semicircular notch. Crack growth results from each laboratory on 7075-T6 bare and LC9cs clad aluminum alloys agreed well and showed that fatigue life was mostly crack propagation from a material defect (inclusion particles or void) or from the cladding layer. Finite-element and weight-function methods were used to determine stress intensity factors for surface and corner cracks in the SENT specimens. Equations were then developed and used in a crack growth and crack-closure model to correlate small- and large-crack data and to make life predictions for various load histories. The cooperative program produced useful experimental data and efficient analysis methods for improving life predictions. The results should ultimately improve aircraft structural reliability and safety.

  10. Investigation on macrosegregation and dendrite morphology during directional solidification of Al-Cu hypereutectic alloys under a strong magnetic field

    Science.gov (United States)

    Li, Xi; Du, DaFan; Fautrelle, Yves; Ren, ZhongMing; Moreau, Rene

    2015-08-01

    The effect of a strong magnetic field (up to 12 T) on the macrosegregation and dendrite morphology during directional solidification of the Al-22at.%Cu alloy has been investigated. Experimental results show that the application of the magnetic field caused the freckle macrosegregation and the fracture of the Al2Cu dendrites during directional solidification. With the increase of the magnetic field, the size of the freckle and dendrite decreases. Moreover, the electron back-scatter diffraction (EBSD) was applied to study the effect of the magnetic field on the morphology and orientation of the Al2Cu dendrite. The EBSD results revealed that although the dendrites were destroyed under the magnetic field, the magnetic field did not yet change the orientation of the Al2Cu crystal. The formation of the freckles and the fracture of the dendrites under the magnetic field may be attributed to the TE magnetic effects.

  11. Microstructure, corrosion behavior and cytotoxicity of biodegradable Mg-Sn implant alloys prepared by sub-rapid solidification.

    Science.gov (United States)

    Zhao, Chaoyong; Pan, Fusheng; Zhao, Shuang; Pan, Hucheng; Song, Kai; Tang, Aitao

    2015-09-01

    In this study, biodegradable Mg-Sn alloys were fabricated by sub-rapid solidification, and their microstructure, corrosion behavior and cytotoxicity were investigated by using optical microscopy, scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy, X-ray diffraction, immersion test, potentiodynamic polarization test and cytotoxicity test. The results showed that the microstructure of Mg-1Sn alloy was almost equiaxed grain, while the Mg-Sn alloys with higher Sn content (Sn≥3 wt.%) displayed α-Mg dendrites, and the secondary dendrite arm spacing of the primary α-Mg decreased significantly with increasing Sn content. The Mg-Sn alloys consisted of primary α-Mg matrix, Sn-rich segregation and Mg2Sn phase, and the amount of Mg2Sn phases increased with increasing Sn content. Potentiodynamic polarization and immersion tests revealed that the corrosion rates of Mg-Sn alloys increased with increasing Sn content. Cytotoxicity test showed that Mg-1Sn and Mg-3Sn alloys were harmless to MG63 cells. These results of the present study indicated that Mg-1Sn and Mg-3Sn alloys were promising to be used as biodegradable implants. PMID:26046288

  12. Effects of zincate treatment on adhesion of electroless Ni-P coating onto various aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Makoto HINO; Koji MURAKAMI; Yutaka MITOOKA; Ken MURAOKA; Teruto KANADANI

    2009-01-01

    The effects of alloying elements on zincate treatment and adhesion of electroless Ni-P coating onto various aluminum alloy substrates were examined. Surface morphology of zinc deposits in the 1st zincate treatment and its adhesion were changed depending on the alloying element. The zinc deposits in the 2nd zincate treatment became thinly uniform, and the adhesion between aluminum alloy substrate and Ni-P coating was improved irrespective of the alloying element. XPS analysis revealed the existence of zinc on the surface of each aluminum alloy substrate after the pickling in 5% nitric acid. This zinc on the surface should be an important factor influencing the morphology of zinc deposit at the 2nd zincate treatment and its adhesion.

  13. Kinetic characterization and of recrystallization of the aluminum alloy 6063 after S work hardening treatment

    International Nuclear Information System (INIS)

    The aluminum 6063 alloy possesses a great industrial interest, presenting characteristics that justify its frequent use, when compared to the other aluminum alloys: the precipitation hardening and high cold work capacity. These alloys present high ductility, that allows their use in operations with high deformation degrees, as the cold work. The objective of this work is to show comparative analysis of the hardness Vickers of the commercial aluminum 6063 alloy, after cold work with different area reduction degree and thermal treatment. Considering the frequent utilization aluminium 6063 alloy, this work studies the characterization and recrystallization of this alloy, after the plastic deformation in different area reduction degrees, thermal treatment and convenient treatment times - Thermo mechanic Treatments. (author)

  14. Laser Surface Alloying of Copper, Manganese, and Magnesium with Pure Aluminum Substrate

    Science.gov (United States)

    Jiru, Woldetinsay G.; Sankar, M. Ravi; Dixit, Uday S.

    2016-03-01

    Laser surface alloying is one of the recent technologies used in the manufacturing sector for improving the surface properties of the metals. Light weight materials like aluminum alloys, titanium alloys, and magnesium alloys are used in the locomotive, aerospace, and structural applications. In the present work, an experimental study was conducted to improve the surface hardness of commercially pure aluminum plate. CO2 laser is used to melt pre-placed powders of pure copper, manganese, and magnesium. Microstructure of alloyed surface was analyzed using optical microscope. The best surface alloying was obtained at the optimum values of laser parameters, viz., laser power, scan speed, and laser beam diameter. In the alloyed region, microhardness increased from 30 HV0.5 to 430 HV0.5, while it was 60 HV0.5 in the heat-affected region. Tensile tests revealed some reduction in the strength and total elongation due to alloying. On the other hand, corrosion resistance improved.

  15. Interface properties and phase formation between surface coated SKD61 and aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Se-Weon CHOI; Young-Chan KIM; Se-Hun CHANG; Ik-Hyun OH; Joon-Sik PARK; Chang-Seog KANG

    2009-01-01

    The intermediate phase formation and surface protection effects between SKD61 die mold alloys and aluminum alloys were investigated during a simulated die-casting process. The surface coatings of SKD61 alloy were carried out via Si pack cementation coatings at 900 ℃ for 10 h and the e-FeSi phase formed. When the coated SKD61 alloy was dipped in the liquid aluminum alloy (ALDC12), the surface coated SKD61 alloys showed better surface properties compared with uncoated SKD61 alloys, i.e., the intermediate phases (FeSiAl compound) were not produced for the coated SKD61 alloy. The coating layer of e-FeSi served as a diffusion barrier for the formation of FeSiAl compounds.

  16. Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

    OpenAIRE

    Atef Korchef; Abdelkrim Kahoul

    2013-01-01

    A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP). The alloy contains a low volume fraction of α-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared wit...

  17. In-plane anisotropy of 1545 aluminum alloy sheet

    Institute of Scientific and Technical Information of China (English)

    PENG Yong-yi; YIN Zhi-min; YANG Jin; DU Yu-xuan

    2005-01-01

    The microstructures and the tensile mechanical properties in the rolling plane of 1545 aluminum alloy sheet at different orientations with respect to the rolling direction were studied by means of tensile test,X-ray diffractometer(XRD),optical microscope and transmission electron microscope.The in-plane anisotropy of tensile mechanical properties was calculated and the inverse pole figures of the rolling plane,transversal section and longitudinal section were obtained by Harris method.The results show that the 1545 Al alloy sheet has remarkable in-plane anisotropy of mechanical properties and the main texture component is{110}texture.On the basis of the model that regards the sheet containing only{110}texture as a monocrystal,the relationship of in-plane anisotropy and the anisotropy of crystallography was analyzed.The study shows that it is the combined effects of the anisotropy of crystallography and microstructures that cause the in-plane anisotropy of mechanical properties,but the main cause is the crystallographic texture.

  18. Long-term strategies for increased recycling of automotive aluminum and its alloying elements.

    Science.gov (United States)

    Løvik, Amund N; Modaresi, Roja; Müller, Daniel B

    2014-04-15

    Aluminum recycling currently occurs in a cascading fashion, where some alloys, used in a limited number of applications, absorb most of the end-of-life scrap. An expected increase in scrap supply in coming decades necessitates restructuring of the aluminum cycle to open up new recycling paths for alloys and avoid a potential scrap surplus. This paper explores various interventions in end-of-life management and recycling of automotive aluminum, using a dynamic substance flow analysis model of aluminum and its alloying elements with resolution on component and alloy level (vehicle-component-alloy-element model). It was found that increased component dismantling before vehicle shredding can be an effective, so far underestimated, intervention in the medium term, especially if combined with development of safety-relevant components such as wheels from secondary material. In the long term, automatic alloy sorting technologies are most likely required, but could at the same time reduce the need for magnesium removal in refining. Cooperation between the primary and secondary aluminum industries, the automotive industry, and end-of-life vehicle dismantlers is therefore essential to ensure continued recycling of automotive aluminum and its alloying elements. PMID:24655476

  19. Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

    Science.gov (United States)

    Florea, Radu Stefanel

    This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

  20. Effect of mixing rate and temperature on primary Si phase of hypereutectic Al-20Si alloy during controlled diffusion solidification (CDS) process

    OpenAIRE

    Yuan-dong Li; Xin-long Zhang; Ying Ma

    2015-01-01

    Controlled Diffusion Solidification (CDS) is a promising process relied on mixing two liquid alloys of precisely controlled chemistry and temperature in order to produce a predetermined alloy composition. In this study, the CDS was employed to prepare hypereutectic Al-20%Si (mass fraction) alloy using Al-30%Si and pure Al of different temperatures. The mixing rate was controlled using three small crucibles with a hole of different diameters in their bottom. The effect of mixing rate and tempe...

  1. Discharge behaviors during plasma electrolytic oxidation on aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Run [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Zhenjiang Watercraft College, Zhenjiang 212000, Jiangsu (China); Wu, Jie [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Xue, Wenbin, E-mail: xuewb@bnu.edu.cn [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Qu, Yao; Yang, Chaolin; Wang, Bin; Wu, Xianying [Key Laboratory for Beam Technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

    2014-11-14

    A plasma electrolytic oxidation (PEO) process was performed on the 2024 aluminum alloy in silicate electrolyte to fabricate ceramic coatings under a constant voltage. Optical emission spectroscopy (OES) was employed to evaluate the characteristics of plasma discharge during PEO process. The plasma electron temperature and density were obtained by analyzing the spectral lines of OES, and the atomic ionization degree in discharge zone was calculated in terms of Saha thermal ionization equation. The illumination intensity of plasma discharge and the temperature in the interior of alloy were measured. Combining the surface morphology and cross-sectional microstructure with the optical emission spectra and illumination at different discharge stage, a discharge model in the growth of PEO ceramic coatings was proposed. It is found that there are two discharge modes of type A with small spark size and type B with large spark size, and the latter only appears in the intermediate stage of PEO process. The illumination intensity has a maximum value in the initial stage of oxidation with many sparks of discharge type A. The electron temperature in plasma discharge zone is about 3000 K–7000 K and atomic ionization degree of Al is about 2.0 × 10{sup −5}–7.2 × 10{sup −3}, which depend on discharge stage. The discharge type B plays a key role on the electron temperature and atomic ionization degree. The electron density keeps stable in the range of about 8.5 × 10{sup 21} m{sup −3}–2.6 × 10{sup 22} m{sup −3}. - Highlights: • The characteristics of PEO plasma discharge was evaluated by OES. • Electron temperature, concentration, atomic ionization degree were calculated. • Discharge model for the growth of PEO coatings was proposed. • Temperature in the interior of alloy during PEO process was measured.

  2. Some properties of aluminum-uranium alloys in the cast, rolled and annealed conditions

    International Nuclear Information System (INIS)

    The metallographic and hardness changes associated with the rolling and subsequent. annealing of aluminum alloys containing up to 30-wt.% uranium have been described. The alloys possessed good rolling properties. However the richer alloys were unusual in that after an initial reduction,, further cold rolling caused softening. In the alloy range examined, increasing uranium contents caused reduced preferred orientation. Qualitative explanations have been proposed to account for the observations on roll softening and preferred orientation. Heat-treating and ageing experiments confirmed that the solid solubility of uranium in aluminum is negligible. (author)

  3. Widmannstätten laths in Ti48Al2Cr2Nb alloy by undercooled solidification

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi; Hu, Rui, E-mail: rhu@nwpu.edu.cn; Yang, Guang; Kou, Hongchao; Zhang, Tiebang; Wang, Jun; Li, Jinshan

    2015-09-15

    Widmannstätten laths in Ti48Al2Cr2Nb alloy were obtained by containerless electromagnetic levitation during undercooled solidification rather than heat treatments in most cases. The nucleation of γ{sub Widmannstätten} is confirmed by the thermal history of the second recalescence behaviour. High dislocation density, stacking faults and dislocation slip are observed by transmission electron microscopy. By quantitative analysis of the transformation energy, the driving force for γ{sub Widmannstätten} in the solid state phase transformation is calculated, compared with that of heat treatments. Meanwhile, the proper undercoolings (ΔT = 257–300 K), post-solidification cooling rates (11.1–29.1 K/s), the fine lamellar colony sizes (306–467 μm) and proper undercoolings in the solid state phase transformation are in favour of promoting the formation of Widmannstätten laths at moderate undercoolings. - Graphical abstract: Display Omitted - Highlights: • Widmannstätten laths were observed in undercooled TiAl alloy. • The influencing factors were discussed in undercooled TiAl alloy. • An analysis of the nucleation of γ{sub Widmannstätten} is carried out.

  4. Fabrication of Aluminum Tubes Filled with Aluminum Alloy Foam by Friction Welding

    Directory of Open Access Journals (Sweden)

    Yoshihiko Hangai

    2015-10-01

    Full Text Available Aluminum foam is usually used as the core of composite materials by combining it with dense materials, such as in Al foam core sandwich panels and Al-foam-filled tubes, owing to its low tensile and bending strengths. In this study, all-Al foam-filled tubes consisting of ADC12 Al-Si-Cu die-cast aluminum alloy foam and a dense A1050 commercially pure Al tube with metal bonding were fabricated by friction welding. First, it was found that the ADC12 precursor was firmly bonded throughout the inner wall of the A1050 tube without a gap between the precursor and the tube by friction welding. No deformation of the tube or foaming of the precursor was observed during the friction welding. Next, it was shown that by heat treatment of an ADC12-precursor-bonded A1050 tube, gases generated by the decomposition of the blowing agent expand the softened ADC12 to produce the ADC12 foam interior of the dense A1050 tube. A holding time during the foaming process of approximately tH = 8.5 min with a holding temperature of 948 K was found to be suitable for obtaining a sound ADC12-foam-filled A1050 tube with sufficient foaming, almost uniform pore structures over the entire specimen, and no deformation or reduction in the thickness of the tube.

  5. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    International Nuclear Information System (INIS)

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated

  6. ENVIRONMENTALLY COMPLIANT CORROSION-ACTIVATED INHIBITOR SYSTEM FOR ALUMINUM ALLOYS - PHASE I

    Science.gov (United States)

    The federal government is estimated to spend $1 billion on painting/repainting aircraft annually. Aircraft have surfaces composed of aluminum alloys that are highly susceptible to corrosion and must be protected with corrosion-preventative treatments that typically conta...

  7. Facile formation of superhydrophobic aluminum alloy surface and corrosion-resistant behavior

    Science.gov (United States)

    Feng, Libang; Yan, Zhongna; Qiang, Xiaohu; Liu, Yanhua; Wang, Yanping

    2016-03-01

    Superhydrophobic surface with excellent corrosion resistance was prepared on aluminum alloy via boiling water treatment and surface modification with stearic acid. Results suggested that the micro- and nanoscale hierarchical structure along with the hydrophobic chemical composition surface confers the aluminum alloy surface with good superhydrophobicity, and the water contact angle and the water sliding angle can reach 156.6° and 3°, respectively. The corrosion resistance of the superhydrophobic aluminum alloy was first characterized by potentiodynamic polarization, and then the long-term corrosion resistance was investigated by immersing the sample in NaCl solution for 90 days. The surface wettability, morphology, and composition before and after immersion were examined, and results showed that the superhydrophobic aluminum alloy surface possessed good corrosion resistance under the experimental conditions, which is favorable for its practical application as an engineering material in seawater corrosion conditions. Finally, the mechanism of the superhydrophobicity and excellent corrosion resistance is deduced.

  8. Computational Modeling aided Near Net Shape Manufacturing for Aluminum Alloys Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This program will focus on developing and validating computational models for near-net shape processing of aluminum alloys. Computational models will be developed...

  9. Fracture toughness and mechanical properties of aluminum alloys for research reactors

    International Nuclear Information System (INIS)

    Aluminum alloys have been used as the structural material of the research reactor or because of their good properties for corrosion resistance and machinability as well as high neutron economy. In order to respond to the needs to maintain the aged core structure and to utilize for the high performance research reactor, irradiation test of aluminum alloys were initiated to provide the data base on the toughness and strength of aluminum alloys aged under research reactor condition. This report describes the results of tensile test, hardness test, Charpy impact test and fracture toughness test on A5052-O and A6061-T6 aluminum alloys under the unirradiated condition. From those tests, it was found that base metal of A5052-O has the highest toughness, welded joints of A5052-O and A6061-T6 is equivalent and have medium toughness, and base metal of A6061-T651 has very low toughness. (author)

  10. Aluminum-Lithium Alloy 2050 for Reduced-Weight, Increased-Stiffness Space Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Touchstone Research Laboratory, along with Alcan Rolled Products ? Ravenswood WV, has identified the Aluminum-Lithium Alloy 2050 as a potentially game-changing...

  11. Quantification of recrystallization texture evolution in cold rolled AA 5182 aluminum alloy

    International Nuclear Information System (INIS)

    The evolution of recrystallization textures in cold rolled AA 5182 aluminum alloy was investigated by X-ray diffraction. The transformation kinetics of recrystallization textures during isothermal annealing was quantified by using an Avrami type equation

  12. Quantification of recrystallization texture evolution in cold rolled AA 5182 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.C.; Zhai, T.; Man, C.-S.; Morris, J.G

    2003-09-15

    The evolution of recrystallization textures in cold rolled AA 5182 aluminum alloy was investigated by X-ray diffraction. The transformation kinetics of recrystallization textures during isothermal annealing was quantified by using an Avrami type equation.

  13. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    Science.gov (United States)

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  14. New water-soluble metal working fluids additives from phosphonic acid derivatives for aluminum alloy materials.

    Science.gov (United States)

    Kohara, Ichitaro; Tomoda, Hideyuki; Watanabe, Shoji

    2007-01-01

    Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short paper describes properties of new additives for water-soluble cutting fluids for aluminum alloy materials. Some alkyldiphosphonic acids were prepared with known method. Amine salts of these phosphonic acids showed anti-corrosion property for aluminum alloy materials. However, they have no hard water tolerance. Monoesters of octylphosphonic acid were prepared by the reaction of octylphosphonic acid dichloride with various alcohols in the presence of triethylamine. Amine salts of monoester of octylphosphonic acid with diethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether and triethyleneglycol monomethyl ether showed both of a good anti-corrosion property for aluminum alloy materials and hard water tolerance. PMID:17898459

  15. Statistical analysis of constituent particles in 7075-T6 aluminum alloy

    Science.gov (United States)

    Harlow, D. G.; Wei, R. P.; Wang, M. Z.

    2006-11-01

    Pitting corrosion is a primary degradation mechanism that affects the durability and integrity of aluminum alloy structures especially in aircraft. The heterogeneity of aluminum alloys is directly responsible for pitting corrosion because about 200 constituent particles per mm2 are on polished surfaces. Corrosion pits commence at surface particles and evolve into severe pits by sustained growth through particle clusters. Severe pits are nuclei for subsequent corrosion fatigue cracking. Thus, heterogeneous clusters of constituent particles are critical to the quality of aluminum alloys subjected to deleterious environments. Models for structural reliability including corrosion fundamentally depend on quantitative descriptions of the spatial statistics of the particles and particle clusters, including their location, size, and density. The primary purpose of this effort is to statistically estimate the distribution functions of the key geometrical properties of the constituent particles in 7075-T6 aluminum alloy and their role in pitting corrosion.

  16. Solidification and microstructural aspects of laser-deposited Ni–Mo–Cr–Si alloy on stainless steel

    Indian Academy of Sciences (India)

    Reena Awasthi; Santosh Kumar; D Srivastava; G K Dey

    2010-12-01

    Laser cladding of stainless steel substrate was carried out using Ni–32Mo–15Cr–3Si (wt%) alloy powder. Laser cladding parameters were optimized to obtain defect-free and metallurgically bonded clad. Variation in solidification rate, cooling rate and compositional variation resulted in heterogeneous microstructure. Microstructure was found to be distinctly different in regions of clad cross-section. Majority of the region was found to consist of eutectic of Mo-rich hcp intermetallic Laves phase and NiFe fcc gamma solid solution phases. Extensive microstructural examinations of different clad regions have been carried out using microscopy and microanalysis techniques.

  17. Phase field simulation of the interface morphology evolution and its stability during directional solidification of binary alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been studied with the B-S phase field model. Simulated results reproduced the morphology transitions of deep cell to shallow cell and shallow cell to plane front. The primary cellular spacing, depth of groove and effective solute redistribution coefficient for different V and G are compared. The absolute stability under high pulling speed and high temperature gradient has also been predicted, which is in agreement with the Mullins-Sekerka (M-S) stability theory.

  18. Corrosion Damage of Aluminum Alloy in Unsymmetric Uimethyl Hydrazine and Dinitrogen Tetroxide Liquid Propellant

    Directory of Open Access Journals (Sweden)

    Zhang Youhong

    2016-01-01

    Full Text Available The high strength aluminum alloy double cantilever beam (DCB specimens were corroded under the conditions of different liquid propellant environment. After the stress corrosion exposure, the scanning electron microscopy and energy-dispersal analyses on corrosion damage were carried out. The corrosion damage sensitivity and the stress corrosion character of the LD10 high strength aluminum alloy in N2O4, UDMH and 3.5% NaCl corrosion solution were analyzed.

  19. Biaxial Testing of 2219-T87 Aluminum Alloy Using Cruciform Specimens

    Science.gov (United States)

    Dawicke, D. S.; Pollock, W. D.

    1997-01-01

    A cruciform biaxial test specimen was designed and seven biaxial tensile tests were conducted on 2219-T87 aluminum alloy. An elastic-plastic finite element analysis was used to simulate each tests and predict the yield stresses. The elastic-plastic finite analysis accurately simulated the measured load-strain behavior for each test. The yield stresses predicted by the finite element analyses indicated that the yield behavior of the 2219-T87 aluminum alloy agrees with the von Mises yield criterion.

  20. Susceptibility of Aluminum Alloys to Corrosion in Simulated Fuel Blends Containing Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, Jeffery K [ORNL; Pawel, Steven J [ORNL; Wilson, Dane F [ORNL

    2013-01-01

    The compatibility of aluminum and aluminum alloys with synthetic fuel blends comprised of ethanol and reference fuel C (a 50/50 mix of toluene and iso-octane) was examined as a function of water content and temperature. Commercially pure wrought aluminum and several cast aluminum alloys were observed to be similarly susceptible to substantial corrosion in dry (< 50 ppm water) ethanol. Corrosion rates of all the aluminum materials examined was accelerated by increased temperature and ethanol content in the fuel mixture, but inhibited by increased water content. Pretreatments designed to stabilize passive films on aluminum increased the incubation time for onset of corrosion, suggesting film stability is a significant factor in the mechanism of corrosion.

  1. Solidification of AM and AZ magnesium alloys characterized by heat-transfer modeled thermal and calorimetric analysis and microsegregation study of directionally solidified microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Mirkovic, Djordje

    2008-05-09

    The micro-scale solidification of commercial Mg alloys of the AZ and AM series is in the focus of the present thesis. Two approaches of investigating solidification are implemented, complementary regarding temperature gradient and solidification rate, and also with respect to the generated microstructure. The first approach considers solidification under a negligible spatial temperature gradient. Here the solidification curves, i.e. fraction solid versus temperature, were determined by developing an improved heat-transfer modeling applicable on both differential thermal analysis (DTA) and differential scanning calorimetry (DSC) signals. The correlation between solidification enthalpy and fraction solid during solidification was tested in detail. A better evaluation of the measured DTA and DSC signals is attained through an independent measurement of the time constant as function of temperature for the applied equipment. A further improvement is achieved through a more impartial interpretation of the measured curves. Both improvements enable a better desmearing of measured signals and reduce the error induced by the operator. The novel tantalum encapsulation enabled appropriate handling of challenging Mg-alloys. The viability and limitations of thermal analysis in general to determine start and end of solidification of AZ magnesium alloys was also studied. The second approach is based on directional solidification in a high temperature gradient and at constant solidification rate, achieved by the Bridgman technique. The resulting dendritic microstructure and inherent microsegregation are studied in this work. The solute profiles, i.e. solute content versus solid phase fraction during solidification, are determined by an advanced treatment of the EPMA data. Problems that are demonstrated in this work are Al-loss and melt pollution due to reaction with typical sample container material made of unprotected steel. The development of an optimized boron nitride (BN

  2. Wear of aluminum and hypoeutectic aluminum-silicon alloys in boundary-lubricated pin-on disk sliding

    Science.gov (United States)

    Ferrante, J.; Brainard, W. A.

    1979-01-01

    The friction and wear of pure aluminum and a number of hypoeutectic aluminum-silicon alloys (with 3 to 12 wt %Si) were studied with a pin-on-disk apparatus. The contacts were lubricated with mineral oil and sliding was in the boundary-lubrication regime at 2.6 cm/sec. Surfaces were analyzed with photomicrographs, scanning electron microscopy, X-ray dispersive analysis, and diamond pyramid hardness measurements. There were two wear regimes for the alloys - high and low - whereas pure aluminum exhibited a high wear rate throughout the test period. Wear rate decreased and the transition stress from high to low wear increased with increasing hardness. There was no correlation between friction coefficient and hardness. A least squares curve fit indicated a wear-rate dependence greater than the inverse first power of hardness. The lower wear rates of the alloys may be due to the composites of silicon platelets in aluminum resulting in increased hardness and thus impairing the shear of the aluminum.

  3. Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys

    International Nuclear Information System (INIS)

    Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys was characterized by transmission electron microscopy. In the weld nugget zone and the thermo-mechanically affected zone some metastable precipitates overaged to equilibrium phase while others solutionized into the aluminum solid solution. In the heat-affected zone the precipitates coarsened.

  4. The Electrical and Mechanical Properties of Porous Anodic 6061-T6 Aluminum Alloy Oxide Film

    OpenAIRE

    Tsung-Chieh Cheng; Chu-Chiang Chou

    2015-01-01

    The properties of the growth of the 6061-T6 aluminum alloy oxide were studied using sulfuric acid anodization. The parameters for the manufacturing process include electrolyte categories, electrolyte concentration, and operating voltages. The results showed that the aluminum oxides obtained by anodization process are mainly amorphous structure and the anodic current density is an important factor affecting the rate of response for oxygen and aluminum ions in barrier. In this experiment, polis...

  5. Cryogenic properties of aluminum and aluminum alloys (citations from the NTIS data base). Report for 1964--Mar 1976

    International Nuclear Information System (INIS)

    Citations of Federally-funded research include studies on the cryogenic properties of aluminum and its alloys used in superconducting machinery, magnets, space technology and nuclear reactors. Electrical properties, fatigue, deformation and welds are included. (This updated bibliography contains 88 abstracts, 18 of which are new entries to the previous edition.)

  6. In situ X-ray observations of gas porosity interactions with dendritic microstructures during solidification of Al-based alloys

    Science.gov (United States)

    Murphy, A. G.; Browne, D. J.; Houltz, Y.; Mathiesen, R. H.

    2016-03-01

    In situ X-radiography solidification experiments were performed on Al-based alloys, using both synchrotron and laboratory-based X-ray sources, in conjunction with a gradient furnace and a newly developed isothermal furnace, respectively. The effect of gas porosity nucleation and growth within the semi-solid mush during both columnar and equiaxed solidification was thereby observed. In all experimental cases examined, gas porosity was observed to nucleate and grow within the field-of-view (FOV) causing various levels of distortion to the semi-solid mush, and thereafter disappearing from the sample leaving no permanent voids within the solidified microstructure. During columnar growth, a single bubble caused severe remelting and destruction of primary trunks leading to secondary fragmentation and evidence of blocking of the columnar front. Equiaxed solidification was performed under microgravity-like conditions with restricted grain motion in the FOV. The degree to which the nucleated gas bubbles affected the surrounding grain structure increased with increasing solid fraction. However, bubble sphericity remained unaffected by apparent solid fraction or grain coherency.

  7. A Front Tracking Model of the MAXUS-8 Microgravity Solidification Experiment on a Ti-45.5at.%Al-8at.%Nb Alloy

    OpenAIRE

    Mooney, Robin P.

    2012-01-01

    On 26th March 2010 the MAXUS-8 sounding rocket was launched from the Esrange Space Center launching facility in Sweden. As part of the Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project, a solidification experiment was conducted on a Ti-45.5at.%Al-8at.%Nb intermetallic alloy in a module on this rocket. The experiment was designed to investigate columnar and equiaxed microstructures in the alloy. A furnace model of the MAXUS 8 experiment with a F...

  8. A Front Tracking Model of the MAXUS-8 Microgravity Solidification Experiment on a Ti-45.5at.% Al-8at.%Nb Alloy

    OpenAIRE

    Mooney, Robin; McFadden, Shaun; Rebow, Marek; Browne, David J.

    2012-01-01

    On 26th March 2010 the MAXUS-8 sounding rocket was launched from the Esrange Space Center in Sweden. As part of the Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project, a solidification experiment was conducted on a Ti-45.5at.%Al-8at.%Nb intermetallic alloy in a module on this rocket. The experiment was designed to investigate columnar and equiaxed microstructures in the alloy. A furnace model of the MAXUS 8 experiment with a Front Tracking Model...

  9. Tribological properties of laser cladding TiB2 particles reinforced Ni-base alloy composite coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Long He; Ye-Fa Tan; Xiao-Long Wang; Qi-Feng Jing; Xiang Hong

    2015-01-01

    To improve the wear resistance of aluminum alloy frictional parts,TiB2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding.The microstructure and tribological properties of the composite coatings were investigated.The results show that the composite coating contains the phases of NiAl,Ni3Al,Al3Ni2,TiB2,TiB,TiC,CrB,and Cr23C6.Its microhardness is HV0.5 855.8,which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy.The friction coefficients of the composite coatings are reduced by 6.8 %-21.6 % and 13.2 %-32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys,while the wear losses are 27.4 %-43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %-32.7 % of those of the aluminum alloys at different loads.At the light loads ranging from 3 to 6 N,the calculated maximum contact stress is smaller than the elastic limit contact stress.The wear mechanism of the composite coatings is micro-cutting wear,but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress.As the loads increase to 12 N,the calculated flash temperature rises to 332.1 ℃.The composite coating experiences multi-plastic deformation wear,micro-brittle fracture wear,and oxidative wear.

  10. A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Liming Liu

    2014-05-01

    Full Text Available Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research.

  11. A benchmark for the validation of solidification modelling algorithms

    Science.gov (United States)

    Kaschnitz, E.; Heugenhauser, S.; Schumacher, P.

    2015-06-01

    This work presents two three-dimensional solidification models, which were solved by several commercial solvers (MAGMASOFT, FLOW-3D, ProCAST, WinCast, ANSYS, and OpenFOAM). Surprisingly, the results show noticeable differences. The results are analyzed similar to a round-robin test procedure to obtain reference values for temperatures and their uncertainties at selected positions in the model. The first model is similar to an adiabatic calorimeter with an aluminum alloy solidifying in a copper block. For this model, an analytical solution for the overall temperature at steady state can be calculated. The second model implements additional heat transfer boundary conditions at outer faces. The geometry of the models, the initial and boundary conditions as well as the material properties are kept as simple as possible but, nevertheless, close to a realistic solidification situation. The gained temperature results can be used to validate self-written solidification solvers and check the accuracy of commercial solidification programs.

  12. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    International Nuclear Information System (INIS)

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly

  13. Application of differential thermal analysis to investigation of magnetic field effect on solidification of Al-Cu hypereutectic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Chuanjun; Yang Hui [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Ren Zhongming, E-mail: zmren@staff.shu.edu.c [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China); Ren Weili; Wu Yuqin [School of Materials Science and Engineering and Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)

    2010-08-27

    Investigation of solidification in the Al-25 at.%Cu hypereutectic alloy in magnetic fields has been carried out by differential thermal analysis (DTA). The DTA results indicated that the nucleation temperatures of primary Al{sub 2}Cu phases and Al-Al{sub 2}Cu eutectics were lowered and the rates of crystal growth including primary phases and eutectics were reduced although the melting of the alloy was almost not affected in magnetic fields of 6 T and 12 T in comparison with those without a magnetic field. The suppression of nucleation and growth of primary phases and eutectics might be mainly attributed to reduction of diffusion rates of atoms in a magnetic field on the condition of suppression of convections. Primary Al{sub 2}Cu phases oriented along a magnetic field compared with disorder ones without a magnetic field, which was caused by the magnetic anisotropy.

  14. Selection Of Cutting Inserts For Aluminum Alloys Machining By Using MCDM Method

    Science.gov (United States)

    Madić, Miloš; Radovanović, Miroslav; Petković, Dušan; Nedić, Bogdan

    2015-07-01

    Machining of aluminum and its alloys requires the use of cutting tools with special geometry and material. Since there exists a number of cutting tools for aluminum machining, each with unique characteristics, selection of the most appropriate cutting tool for a given application is very complex task which can be viewed as a multi-criteria decision making (MCDM) problem. This paper is focused on multi-criteria analysis of VCGT cutting inserts for aluminum alloys turning by applying recently developed MCDM method, i.e. weighted aggregated sum product assessment (WASPAS) method. The MCDM model was defined using the available catalogue data from cutting tool manufacturers.

  15. Fabrication of super-hydrophobic surfaces on aluminum alloy substrates by RF-sputtered polytetrafluoroethylene coatings

    International Nuclear Information System (INIS)

    In this work, we present a method of fabricating super-hydrophobic surface on aluminum alloy substrate. The etching of aluminum surfaces has been performed using Beck's dislocation etchant for different time to create micrometer-sized irregular steps. An optimised etching time of 50 s is found to be essential before polytetrafluoroethylene (PTFE) coating, to obtain a highest water contact angle of 165±2° with a lowest contact angle hysteresis as low as 5±2°. The presence of patterned microstructure as revealed by scanning electron microscopy (SEM) together with the low surface energy ultrathin RF-sputtered PTFE films renders the aluminum alloy surfaces highly super-hydrophobic

  16. Effects of Rapid Solidification Process and 0.1 wt.% Pr Addition on Properties of Sn-9Zn Alloy and Cu/Solder/Cu Joints

    Science.gov (United States)

    Zhao, Guoji; Jing, Yanxia; Sheng, Guangmin; Chen, Jianhua

    2016-05-01

    Effects of 0.1 wt.% Pr addition and rapid solidification process on Sn-9Zn solder alloy were investigated. Solder characteristics of the as-solidified and rapidly solidified Sn-9Zn-0.1Pr alloys were analyzed in comparison with those of the as-solidified Sn-9Zn alloy. Mechanical properties and interfacial microstructure of solder/Cu joints obtained using these solders were comparatively studied. By comparison with the as-solidified Sn-9Zn alloy, the wettability of the solder was obviously improved with 0.1 wt.% Pr addition, and the melting behavior of the solder was promoted due to the rapid solidification process. The corrosion resistance of Sn-9Zn-0.1Pr alloy was improved due to the refined microstructure resulting from 0.1 wt.% Pr addition and rapid solidification. The growth of IMCs at the interface of Sn-9Zn-0.1Pr/Cu joints was depressed in some degree. Rapid solidification process promoted the interfacial reaction during soldering and improved the bonding strength of joints.

  17. Calculation of Liquidus Temperature for Aluminum and Magnesium Alloys Applying Method of Equivalency

    Directory of Open Access Journals (Sweden)

    Mile B. Djurdjević

    2013-01-01

    Full Text Available The purpose of this paper is to develop a mathematical equation, which will be able to accurately predict the liquidus temperature of various aluminum and magnesium cast alloys on the basis of their known chemical compositions. An accurate knowledge of liquidus temperature permits a researcher to predict a variety of physical parameters pertaining to a given alloy. The analytical expressions presented in this paper are based on the “method of equivalency.” According to this concept, the influence of any alloying element on the liquidus temperature of an aluminum and/or magnesium alloy can be translated into the equivalent influence of a reference element. Silicon as a reference element has been chosen for aluminum alloys and aluminum for magnesium alloys. The sum of the equivalent concentrations for other elements, when added to the influence of the actual reference element is used to calculate the liquidus temperature of the alloy. The calculated liquidus temperatures for wide ranges of alloy chemical compositions show a good correlation with corresponding measured liquidus temperatures.

  18. Solidification and Microstructural Evolution of Hypereutectic Al-15Si-4Cu-Mg Alloys with High Magnesium Contents

    Science.gov (United States)

    Tebib, M.; Ajersch, F.; Samuel, A. M.; Chen, X.-G.

    2013-09-01

    The low coefficient of thermal expansion and good wear resistance of hypereutectic Al-Si-Mg alloys with high Mg contents, together with the increasing demand for lightweight materials in engine applications have generated an increasing interest in these materials in the automotive industry. In the interests of pursuing the development of new wear-resistant alloys, the current study was undertaken to investigate the effects of Mg additions ranging from 6 to 15 pct on the solidification behavior of hypereutectic Al-15Si-4Cu-Mg alloy using thermodynamic calculations, thermal analysis, and extensive microstructural examination. The Mg level strongly influenced the microstructural evolution of the primary Mg2Si phase as well as the solidification behavior. Thermodynamic predictions using ThermoCalc software reported the occurrence of six reactions, comprising the formation of primary Mg2Si; two pre-eutectic binary reactions, forming either Mg2Si + Si or Mg2Si + α-Al phases; the main ternary eutectic reaction forming Mg2Si + Si + α-Al; and two post-eutectic reactions resulting in the precipitation of the Q-Al5Mg8Cu2Si6 and θ-Al2Cu phases, respectively. Microstructures of the four alloys studied confirmed the presence of these phases, in addition to that of the π-Al8Mg3FeSi6 (π-Fe) phase. The presence of the π-Fe phase was also confirmed by thermal analysis. The morphology of the primary Mg2Si phase changed from an octahedral to a dendrite form at 12.52 pct Mg. Any further Mg addition only coarsened the dendrites. Image analysis measurements revealed a close correlation between the measured and calculated phase fractions of the primary Mg2Si and Si phases. ThermoCalc and Scheil calculations show good agreement with the experimental results obtained from microstructural and thermal analyses.

  19. Corrosion Behavior of Commercial Aluminum Alloy Processed by Equal Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Atef Korchef

    2013-01-01

    Full Text Available A commercial aluminum alloy was subjected to severe plastic deformation through equal channel angular pressing (ECAP. The alloy contains a low volume fraction of α-AlFeSi located essentially at the grain boundaries. The corrosion behavior of the ECAP’ed alloy was investigated in NaCl solution using potentiodynamic polarization and immersion tests. The effects of scan rate and NaCl concentration on the alloy susceptibility to corrosion were also studied. The results obtained were compared with those of the nonpressed alloy. ECAP leads to an intensive grain refinement accompanied by an increased dislocation density. All electrochemical tests confirm that corrosion resistance of the alloy remarkably diminished with increasing the ECAP number of passes. This is presumably due to the breakdown of the α-AlFeSi after ECAP leading to higher number of galvanic cells and enhanced dissolution of the aluminum matrix.

  20. Heat treatment of Aluminum bronze, alloyed with Iron and Nickel, investigation on the structure and hardness

    International Nuclear Information System (INIS)

    Full text: The present study describes the changes after the heat treatment on the microstructure and hardness of copper-aluminum alloys, additionally alloyed with Fe and Ni. The influence of these elements provokes changes in the microstructure of the alloys, which is largely determined by its presence in the composition and by the different heat treatment regimes. Investigations were made in the case that the content of the additional alloying elements is fixed on 3%. Data will be obtained for changes in the structure and hardness of the specimens as a result of the heat treatment, as these characteristics are changed in the cases of alloying with Fe and Ni. key words: Copper-aluminum alloys, heat treatment, microstructure

  1. Roping in 6111 aluminum alloys with various iron contents

    Energy Technology Data Exchange (ETDEWEB)

    Jin, H. [Novelis Global Technology Centre, Novelis Inc., P.O. Box 8400, Kingston, Ont., K7L 5L9 (Canada)]. E-mail: haiou.jin@novelis.com; Lloyd, D.J. [Novelis Global Technology Centre, Novelis Inc., P.O. Box 8400, Kingston, Ont., K7L 5L9 (Canada)

    2005-08-25

    The development of surface roughness and roping after straining and its correlation with grain size and texture were investigated in AA6111 aluminum alloys with various Fe contents, using optical microscopy, scanning electron microscopy (SEM), electron back scatter diffraction (EBSD) in SEM, X-ray diffraction, and 3D non-contact profilometry. It has been demonstrated that the spatial distribution of texture components is a critical factor for roping. When the {l_brace}0 0 1{r_brace}<1 0 0> (cube) and {l_brace}0 1 1{r_brace}<1 0 0> (Goss) texture components are banded along the rolling direction (RD) and alternately distributed in the transverse direction (TD), intensive roping develops when the sheet is stretched in the TD regardless of grain size. During rolling the cube and Goss are metastable orientations in AA6111 and form cube and Goss bands along the RD. These bands are the preferred nucleation sites for recrystallization, resulting in the banded structure being retained in the final solutionised sheet. Increasing the Fe content leads to a finer grain size and lower strain induced surface roughness, but roping is insensitive to the Fe content and simply dependent on the degree of cold rolling prior to solutionising.

  2. Rheological behavior of continuous roll casting process of aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAN Li-hua; ZHONG Jue; LI Xiao-qian; HUANG Ming-hui

    2005-01-01

    The rheological behavior of aluminum alloy and its influencing factors in physical simulation of continuous roll casting process were studied by using a Gleeble-1500 thermal-mechanical simulation tester with a set of special clamp system. The relationships between the flow stress and the strain rate in the deformation process of simulating roll casting experiment were obtained. The results show that four different characteristic stages exist in the temperature range of the whole rheological process. The first occurs when the temperature is higher than 600℃, which belongs to the creep deformation stage; the second occurs when the temperature lies in the range of 500-600℃, and it can be regarded as the high temperature and low stress level deformation stage; the third occurs when the temperature decreases to the range of 300-500℃, it is considered to be the middle stress level deformation stage; the last occurs when the temperature is less than 300℃ and the strain rate is less than 1.00 s -1, it belongs to middle stress level deformation stage. But when the strain rate is larger than 1.00 s -1, it belongs to the high stress level deformation stage. And the relative constitutive models suitable for the four different stages of continuous roll casting process were established through multivariate linear regression analysis of the experimental data.

  3. Roping in 6111 aluminum alloys with various iron contents

    International Nuclear Information System (INIS)

    The development of surface roughness and roping after straining and its correlation with grain size and texture were investigated in AA6111 aluminum alloys with various Fe contents, using optical microscopy, scanning electron microscopy (SEM), electron back scatter diffraction (EBSD) in SEM, X-ray diffraction, and 3D non-contact profilometry. It has been demonstrated that the spatial distribution of texture components is a critical factor for roping. When the {0 0 1} (cube) and {0 1 1} (Goss) texture components are banded along the rolling direction (RD) and alternately distributed in the transverse direction (TD), intensive roping develops when the sheet is stretched in the TD regardless of grain size. During rolling the cube and Goss are metastable orientations in AA6111 and form cube and Goss bands along the RD. These bands are the preferred nucleation sites for recrystallization, resulting in the banded structure being retained in the final solutionised sheet. Increasing the Fe content leads to a finer grain size and lower strain induced surface roughness, but roping is insensitive to the Fe content and simply dependent on the degree of cold rolling prior to solutionising

  4. Strengthening of Aluminum Alloy 2219 by Thermo-mechanical Treatment

    Science.gov (United States)

    Li, Xifeng; Lei, Kun; Song, Peng; Liu, Xinqin; Zhang, Fei; Li, Jianfei; Chen, Jun

    2015-10-01

    Strengthening of aluminum alloy 2219 by thermo-mechanical treatment has been compared with artificial aging. Three simple deformation modes including pre-stretching, compression, and rolling have been used in thermo-mechanical treatment. The tensile strength, elongation, fracture feature, and precipitated phase have been investigated. The results show that the strengthening effect of thermo-mechanical treatment is better than the one of artificial aging. Especially, the yield strength significantly increases with a small decrease of elongation. When the specimen is pre-stretched to 8.0%, the yield strength reaches 385.0 MPa and increases by 22.2% in comparison to the one obtained in aging condition. The maximum tensile strength of 472.4 MPa is achieved with 4.0% thickness reduction by compression. The fracture morphology reveals locally ductile and brittle failure mechanism, while the coarse second-phase particles distribute on the fracture surface. The intermediate phases θ″ or θ' orthogonally precipitate in the matrix after thermo-mechanical treatment. As compared to artificial aging, the cold plastic deformation increases distribution homogeneity and the volume fraction of θ'' or θ' precipitates. These result in a better strengthening effect.

  5. Accelerated corrosion test and corrosion failure distribution model of aircraft structural aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-lin; MU Zhi-tao; JIN Ping

    2006-01-01

    Based on corrosion damage data of 10 years for a type of aircraft aluminum alloy, the statistical analysis was conducted by Gumbel, Normal and two parameters Weibull distribution function. The results show that aluminum alloy structural member has the corrosion history of pitting corrosion-intergranular corrosion-exfoliation corrosion, and the maximum corrosion depth is in conformity to normal distribution. The accelerated corrosion test was carried out with the complied equivalent airport accelerated environment spectrum. The corrosion damage failure modes of aluminum alloy structural member indicate that the period of validity of the former protective coating is about 2.5 to 3 years, and that of the novel protective coating is about 4.0 to 4.5 years. The corrosion kinetics law of aluminum spar flange was established by fitting corrosion damage test data. The law indicates two apparent corrosion stages of high strength aluminum alloy section material: pitting corrosion and intergranular corrosion/exfoliation corrosion.The test results agree with the statistical fit result of corrosion data collected from corrosion member in service. The fractional error is 5.8% at the same calendar year. The accelerated corrosion test validates the corrosion kinetics law of aircraft aluminum alloy in service.

  6. Effect of micro alloying elements on the interfacial reactions between molten aluminum alloy and tool steel

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, K.A. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Shabestari, S.G. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of)], E-mail: shabestari@iust.ac.ir

    2009-06-10

    The morphology and growth kinetics of intermetallic compounds that are formed in the interface of H13 tool steel and A380 molten aluminum has been investigated through immersion experiments. The effect of addition of micro alloying elements to the melt on the formation and thickness of intermetallic layer was also studied. Microstructural investigation showed that three intermetallic layers formed through the liquid-solid reaction during immersion of steel samples in the liquid aluminum at a temperature of 680 deg. C for the duration time of 2 min to 2.5 h. These intermetallic compounds are Al{sub 8}Fe{sub 2}Si, Al{sub 5}FeSi and Al{sub 12}Fe{sub 5}Si. The effect of nitride coating of the surface of H13 steel on the growth of intermetallic phases has also been studied. Micro alloying elements such as strontium and titanium have been used in the melt and their effects on the morphology of intermetallic compound and their growth rate have been investigated by the immersion experiments at the temperature of 680 deg. C for the time of 0.5-2.5 h. The results showed that two layers of Al{sub 8}Fe{sub 2}Si and Al{sub 5}FeSi formed at the interface and Al{sub 12}Fe{sub 5}Si layer was not observed. Nitride coating decreased the overall thickness of the intermetallic layer about 50% after immersion time of 0.5 h. Addition of micro alloying elements such as Sr (0.05 wt%) and Ti (0.2 wt%) to the melt decreased the total thickness of the intermetallic layer about 31% after immersion of steel for 0.5 h in the melt. Both nitride coating and addition of strontium (0.05 wt%) and titanium (0.2 wt%) micro alloying elements to the melt had the most influence on decreasing the overall thickness of the intermetallic layer. The thickness of the intermetallic layer decreased about 60% after immersion of steel for 2.5 h in the aluminum melt. The experimental results clearly indicate the beneficial effect of strontium on the kinetics of the formation and growth of the intermetallic layers.

  7. Effect of micro alloying elements on the interfacial reactions between molten aluminum alloy and tool steel

    International Nuclear Information System (INIS)

    The morphology and growth kinetics of intermetallic compounds that are formed in the interface of H13 tool steel and A380 molten aluminum has been investigated through immersion experiments. The effect of addition of micro alloying elements to the melt on the formation and thickness of intermetallic layer was also studied. Microstructural investigation showed that three intermetallic layers formed through the liquid-solid reaction during immersion of steel samples in the liquid aluminum at a temperature of 680 deg. C for the duration time of 2 min to 2.5 h. These intermetallic compounds are Al8Fe2Si, Al5FeSi and Al12Fe5Si. The effect of nitride coating of the surface of H13 steel on the growth of intermetallic phases has also been studied. Micro alloying elements such as strontium and titanium have been used in the melt and their effects on the morphology of intermetallic compound and their growth rate have been investigated by the immersion experiments at the temperature of 680 deg. C for the time of 0.5-2.5 h. The results showed that two layers of Al8Fe2Si and Al5FeSi formed at the interface and Al12Fe5Si layer was not observed. Nitride coating decreased the overall thickness of the intermetallic layer about 50% after immersion time of 0.5 h. Addition of micro alloying elements such as Sr (0.05 wt%) and Ti (0.2 wt%) to the melt decreased the total thickness of the intermetallic layer about 31% after immersion of steel for 0.5 h in the melt. Both nitride coating and addition of strontium (0.05 wt%) and titanium (0.2 wt%) micro alloying elements to the melt had the most influence on decreasing the overall thickness of the intermetallic layer. The thickness of the intermetallic layer decreased about 60% after immersion of steel for 2.5 h in the aluminum melt. The experimental results clearly indicate the beneficial effect of strontium on the kinetics of the formation and growth of the intermetallic layers.

  8. Effect of Zr addition on fracture toughness of 2048 high strength aluminum alloy

    International Nuclear Information System (INIS)

    The effect of replacing grain refining element Mn by Zr on fracture toughness of 2048 aluminum alloys was investigated. Fracture toughness changed by Zr replacement was analyed as follows. 1. Quantity of large inclusions gave a primary effect on fracture toughness when grain size and material strength level were kept constant. 2. Dispersoids of Mn compounds were rod shape and 1.0μm in length, while those of Zr compound, Al3Zr were spherical and 0.1μm in diameter. Dispersoids of Zr compounds, Al3Zr were better than those of Mn compounds for improving fracture toughness. 3. Experimentally proved the effects of dispersoids change on fracture toughness of aluminum alloy 2048 when other metallurgical factors -grain size, inclusion, strength level- were kept constant. Zr bearing modified 2048 aluminum aiioy showed 5% improvement in yield strength and 50% in toughness compared with those of Mn bearing conventional 2048 aluminum alloy. (Author)

  9. Adhesion enhancement of titanium nitride coating on aluminum casting alloy by intrinsic microstructures

    Science.gov (United States)

    Nguyen, Chuong L.; Preston, Andrew; Tran, Anh T. T.; Dickinson, Michelle; Metson, James B.

    2016-07-01

    Aluminum casting alloys have excellent castability, high strength and good corrosion resistance. However, the presence of silicon in these alloys prevents surface finishing with conventional methods such as anodizing. Hard coating with titanium nitride can provide wear and corrosion resistances, as well as the aesthetic finish. A critical factor for a durable hard coating is its bonding with the underlying substrate. In this study, a titanium nitride layer was coated on LM25 casting alloy and a reference high purity aluminum substrate using Ion Assisted Deposition. Characterization of the coating and the critical interface was carried out by a range of complementing techniques, including SIMS, XPS, TEM, SEM/EDS and nano-indentation. It was observed that the coating on the aluminum alloy is stronger compared to that on the pure aluminum counterpart. Silicon particles in the alloy offers the reinforcement though mechanical interlocking at microscopic level, even with nano-scale height difference. This reinforcement overcomes the adverse effect caused by surface segregation of magnesium in aluminum casting alloys.

  10. Influence of Shot Peening on Failure of an Aluminum Alloy Exposed to Aggressive Aqueous Environments

    Science.gov (United States)

    Lv, Shengli; Cu, You; Zhang, Wei; Tong, Xiaoyan; Srivatsan, T. S.; Gao, Xiaosheng

    2013-06-01

    Pre-corrosion damage tests were performed on the high strength aluminum alloy (Al-Zn-Mg-Cu) that was subject to shot peening surface treatment. The tests were performed for different time levels and compared one-on-one with the performance and characteristics of the non-shot-peened alloy. The residual stress induced by the shot peening surface treatment for two different intensity levels was measured using the method of incremental drilling of holes. Based on an observation of morphology of corrosion experienced by the aluminum alloy the depth of corrosion was measured using a laser displacement sensor. The surface of the aluminum alloy that was shot peened revealed an overall better resistance to pitting while concurrently revealing evidence of partial degradation. The depth of degradation is related to the residual stress that is induced in the aluminum alloy sample by the shot peening treatment. The key mechanisms that control damage during corrosion of the shot-peened aluminum alloy can be divided into the distinct stages of (a) initial occurrence of uniform corrosion followed by (b) the generation of degradation, and (c) culminating in the initiation of pitting once the depth of degradation reaches a certain level.

  11. Correlation between shear punch and tensile data for neutron-irradiated aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, M.L.; Edwards, D.J. [Pacific Northwest Laboratory, Richland, WA (United States); Toloczko, M.B. [Univ. of California, Santa Barbara, CA (United States)] [and others

    1995-04-01

    This work was performed to determine whether shear punch and tensile data obtained on neutron irradiated aluminum alloys exhibited the same type of relationship as had been seen in other work and to assess the validity of extrapolating the results to proton-irradiated alloys. This work was also meant to be the first of a series of similar test matrices designed to determine whether the shear punch/tensile relationship varied or was the same for different alloy classes.

  12. The investigation on the stratification phenomenon of aluminum rear alloyed layer in silicon solar cells

    International Nuclear Information System (INIS)

    Highlights: • A stratification phenomenon of Al rear alloyed layer in solar cells is found. • The stratification phenomenon is related to the formula of the paste. • From the analyses, the stratification phenomenon is redundant and deleterious. • The highest cell's efficiency without stratification phenomenon is close to 20%. - Abstract: A stratification phenomenon of aluminum rear alloyed layer was found in the study of aluminum rear emitter N-type solar cells. It is related to the composition of the paste. The outer aluminum alloyed layer can be called as aluminum doped emitter, and it gives the contribution to the junction formation. The inner layer is only the Al/Si mixed layer. The aluminum atoms in this layer are not bonded with silicon atoms. This inner layer will ruin the quality of the rear junction. The shunt resistance, reverse current density and the junction electric leakage value are getting worse when the thickness of the inner layer increases. The thickness of the inner Al/Si mixed layer increases with the increasing of firing temperature, while the depth of the aluminum doped emitter almost does not change. From the analyses, the inner Al/Si mixed layer is redundant and deleterious. Only a single deep aluminum doped rear emitter is needed for N-type solar cells. The highest power conversion efficiency of 19.93% for aluminum rear emitter N-type cells without the stratification phenomenon has been obtained

  13. Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

    OpenAIRE

    Takashi Harumoto; Yohei Tamura; Takashi Ishiguro

    2015-01-01

    Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabri...

  14. Aluminum base alloy powder metallurgy process and product

    Science.gov (United States)

    Paris, Henry G. (Inventor)

    1986-01-01

    A metallurgical method including cooling molten aluminum particles and consolidating resulting solidified particles into a multiparticle body, wherein the improvement comprises the provision of greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn. Aluminum containing greater than 0.15% of a metal which diffuses in the aluminum solid state at a rate less than that of Mn.

  15. A front tracking model of the MAXUS-8 microgravity solidification experiment on a Ti-45.5at.% Al-8at.%Nb alloy

    International Nuclear Information System (INIS)

    On 26th March 2010 the MAXUS-8 sounding rocket was launched from the Esrange Space Center in Sweden. As part of the Intermetallic Materials Processing in Relation to Earth and Space Solidification (IMPRESS) project, a solidification experiment was conducted on a Ti-45.5at.%Al-8at.%Nb intermetallic alloy in a module on this rocket. The experiment was designed to investigate columnar and equiaxed microstructures in the alloy. A furnace model of the MAXUS 8 experiment with a Front Tracking Model of solidification has been developed to determine the macrostructure and thermal history of the samples in the experiment. This paper gives details of results of the front tracking model applied to the MAXUS 8 microgravity experiment. A model for columnar growth is presented and compared to experimental results for furnace A of the experiment module.

  16. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-07-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  17. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-06-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  18. The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy

    Science.gov (United States)

    Bochkareva, Anna; Lunev, Aleksey; Barannikova, Svetlana; Gorbatenko, Vadim; Shlyakhova, Galina; Zuev, Lev

    2015-10-01

    The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. Using scanning electron and atomic force microscopy methods, the changes in the fracture surface were investigated. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h.

  19. The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy

    International Nuclear Information System (INIS)

    The effect of hydrogen embrittlement on the localized plastic deformation of aluminum alloy D1 was investigated. The studies were performed for the test samples of aluminum alloy subjected to electrolytic hydrogenation. It is found that the mechanical properties and localized plastic deformation parameters of aluminum alloy are affected adversely by hydrogen embrittlement. The hydrogenated counterpart of alloy has a lower degree of ductility relative to the original alloy; however, the plastic flow behavior of material remains virtually unaffected. Using scanning electron and atomic force microscopy methods, the changes in the fracture surface were investigated. The deformation diagrams were examined for the deformed samples of aluminum alloy. These are found to show all the plastic flow stages: the linear, parabolic and pre-failure stages would occur for the respective values of the exponent n from the Ludwik-Holomon equation. Using digital speckle image technique, the local strain patterns were being registered for the original alloy D1 and the counterpart subjected to electrolytic hydrogenation for 100 h

  20. Impurity control and corrosion resistance of magnesium-aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M. [GM China Lab; Song, GuangLing [ORNL

    2013-01-01

    The corrosion resistance of magnesium alloys is very sensitive to the contents of impurity elements such as iron. In this study, a series of diecast AXJ530 magnesium alloy samples were prepared with additions of Mn and Fe. Through a comprehensive phase diagram calculation and corrosion evaluation, the mechanisms for the tolerance limit of Fe in magnesium alloy are discussed. This adds a new dimension to control the alloying impurity in terms of alloying composition design and casting conditions.

  1. Odontologic use of copper/aluminum alloys: mitochondrial respiration as sensitive parameter of biocompatibility

    Directory of Open Access Journals (Sweden)

    Rodrigues Luiz Erlon A.

    2003-01-01

    Full Text Available Copper/aluminum alloys are largely utilized in odontological restorations because they are less expensive than gold or platinum. However, tarnishing and important corrosion in intrabuccal prostheses made with copper/aluminum alloys after 28 days of use have been reported. Several kinds of food and beverage may attack and corrode these alloys. Copper is an essential component of several important enzymes directly involved in mitochondrial respiratory metabolism. Aluminum, in contrast, is very toxic and, when absorbed, plasma values as small as 1.65 to 21.55 mg/dl can cause severe lesions to the nervous system, kidneys, and bone marrow. Because mitochondria are extremely sensitive to minimal variation of cellular physiology, the direct relationship between the mitocondrial respiratory chain and cell lesions has been used as a sensitive parameter to evaluate cellular aggression by external agents. This work consisted in the polarographic study of mitochondrial respiratory metabolism of livers and kidneys of rabbits with femoral implants of titanium or copper/aluminum alloy screws. The experimental results obtained did not show physiological modifications of hepatic or renal mitochondria isolated from animals of the three experimental groups, which indicate good biocompatibility of copper/aluminum alloys and suggest their odontological use.

  2. Study on shear resistance of aluminum alloy I-section members

    Institute of Scientific and Technical Information of China (English)

    Zhen DONG; Qilin ZHANG

    2008-01-01

    The design method for the shear resistance of aluminum alloy I-section members is presented, taking into consideration of the post-buckling strength of webs and the restraint effect of flanges, and the practical design formulas are proposed. The deflection of aluminum alloy I-section members under concentrated load is simulated by using the finite element method, and several design theories are discussed. The relation of shear resistance to the maximum web displacement reflects that the web of aluminum alloy I-section member is under fewer shears buckling force, while the whole member has higher shear resistance. However, the traditional design method is not able to give the real shear resistance of aluminum alloy I-section members. The proposed design formulas for the shear resistance of aluminum alloy I-section members is used to calculate accurately the post-buckling resistance of webs and the shear resistance contribution of flanges. The results are in a great agreement with the test data of Hamoodi M J, Burr C A, Evans H R and the results from Eurocode9 formulas.

  3. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    Science.gov (United States)

    Zhang, H. S.; Yan, M.; Wang, H. Y.; Shen, L. T.; Dai, L. H.

    2016-04-01

    A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa), the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  4. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    Directory of Open Access Journals (Sweden)

    H. S. Zhang

    2016-04-01

    Full Text Available A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa, the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  5. Microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system.

    Science.gov (United States)

    Yang, S S; Lin, J Y; Lin, Y T

    1998-09-01

    To investigate the microbiologically induced corrosion of aluminum alloys in fuel-oil/aqueous system, aluminum alloys A356, AA 5052, AA 5083 and AA 6061 were chosen as the test alloys and Cladosporium and several fuel-oil contaminated microbes isolated in Taiwan were used as test organisms. Aluminum alloy AA 5083 in fuel-oil/aqueous system was the most susceptible material for microbial corrosion, then followed by aluminum alloys AA 5052 and A356, and AA 6061 was more resistant to microbial aggression. Mixed culture had high capability of corrosion, then followed by Penicillium sp. AM-F5, Fusarium sp. AM-F1, Pseudomonas aeruginosa AM-B5, Ps. fluorescens AM-B9, C. resinae ATCC 22712, Penicillium sp. AM-F2, Candida sp. AM-Y1 and Ps. aeruginosa AM-B11. From energy dispersive spectrometer analysis, aluminum and magnesium contents decreased in the corrosion area, while chlorine and sulfur contents increased. The major organic acid produced in fuel-oil/aqueous system was acetic acid, and the total organic acids content had a positive correlation with the degree of microbial corrosion. PMID:10496152

  6. The Effects of Corrosive Media on Fatigue Performance of Structural Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Huihui Yang

    2016-07-01

    Full Text Available The effects of corrosive media on rotating bending fatigue lives (the cyclic numbers from 104 to 108 of different aluminum alloys were investigated, which involved the corrosion fatigue lives of five kinds of aluminum alloys in air, at 3.5 wt. % and 5.0 wt. % NaCl aqueous solutions. Experimental results indicate that corrosive media have different harmful influences on fatigue lives of different aluminum alloys, in which the differences of corrosion fatigue lives depend strongly on the plastic property (such as the elongation parameter of aluminum alloys and whether to exist with and without fracture mode II. The other various influence factors (such as the dropping corrosive liquid rate, the loading style, and the nondimensionalization of strength of corrosion fatigue lives in three media were also discussed in detail by using the typical cases. Furthermore, fracture morphologies and characteristics of samples, which showed the different fatigue cracking behaviors of aluminum alloys in three media, were investigated by scanning electron microscopy (SEM in this paper.

  7. Development of Deformation-Semisolid-Casting (D-SSC) Process and Applications to Some Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Recent advances in the semisolid casting technologies are introduced for aluminum alloys. The advantages of the rheocast and thixocast methods to fabricate alloys with refined spheroidized α-Al particles are described.The deformation-semisolid-casting (D-SSC) process developed by the author's group is presented. The D-SSC process is extremely effective to produce microstructures of refined intermetallic compound particles as well as the spheroidized α-Al particles in the Al-Si based alloys containing highly concentrated Fe. In the D-SSC processed Al-Si-Cu alloy high elongation of about 20% was achieved even contained concentrated impurity of Fe. The D-SSC process is also useful to produce wrought aluminum alloys with microstructures of refined α-Al particles.

  8. A study of hydrogen permeation in aluminum alloy treated by various oxidation processes

    International Nuclear Information System (INIS)

    A set of oxide coatings was formed on the surface of an Al alloy (wt%: Fe, 0.24; Si, 1.16; Cu, 0.05-0.2; Zn, 0.1; Al, residual) by means of various oxidation processes. The hydrogen permeability through the aluminum alloy and its coating materials was determined by a vapor phase permeation technique at temperatures ranging from 400 to 500 C using high-purity H2 (99.9999%) gas with an upstream hydrogen pressure of 104-105 Pa. The experimental results show that the hydrogen permeability through aluminum oxide coating is 100-2000 times lower than that through the aluminum alloy substrate. This means that the aluminum oxide is a significant hydrogen permeation barrier. A high hydrogen permeation resistance was observed in an oxide layer prefilmed in 200 C water, while an anodized aluminum oxide film had a less obstructive effect, possibly caused by the porous structure of the anodic oxide. The hydrogen permeability through films of aluminum oxide was not a simple function of the aluminum-oxide phase configuration. (orig.)

  9. Influence of solidification parameters on the cellular sub-structure of tin and some tin alloys

    International Nuclear Information System (INIS)

    This paper describes an attempt to obtain qualitative data on sub-structure of samples solidified in contact with the cooler. The objective of experiments was to study micro segregation phenomena by investigating the substructure in the solidified sample obtained under experimental conditions which are similar to real solidification conditions

  10. Effect of homogenization and alloying elements on hot deformation behaviour of 1XXX series aluminum alloys

    Science.gov (United States)

    Shakiba, Mohammad

    containing various Mn (0.1 and 0.2 wt%) and Cu (0.05, 0.18 and 0.31 wt%) contents was also investigated. It was found that both manganese and copper in solid solution have a significant influence on the hot workability of dilute Al-Fe-Si alloys. On a wt% basis, Mn exhibits a stronger strengthening effect compared to Cu. The activation energies for deformation were calculated from experimental data for all the alloys investigated. With a 0.2 wt% Mn addition, the activation energy increased from 161 and 176 kJ/mol for low-Fe (0.1wt%) and high-Fe (0.5wt%) base alloys to 181 and 192 kJ/mol, respectively. The addition of Cu up to 0.31 wt% only slightly increased the activation energy of low-Fe base alloy from 161 to 166 kJ/mol. Solute diffusion acted as the deformation rate controlling mechanism in these dilute alloys. Mn containing alloys have higher flow stress and higher activation energy due to the considerably lower diffusion rate of Mn in aluminum compared to Cu containing alloys. An addition of Mn and Cu also retarded the dynamic recovery and resulted in a decrease in the subgrain size and mean misorientation angle of the grain boundaries. In addition, based on hot compression tests, an artificial neural network model was developed to predict the high temperature flow behavior of Al-0.12Fe-0.1Si-Cu alloys as a function of chemical composition (with Cu contents of 0.002-0.31wt%) and process parameters. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study to predict the flow behavior of Al-0.12Fe-0.1Si alloy with various levels of Cu addition (0.002-0.31wt%) at different deformation conditions. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using various standard statistical parameters. An excellent agreement between experimental and predicted results was obtained. Sensitivity

  11. Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications

    International Nuclear Information System (INIS)

    Aluminum and magnesium are two highly important lightweight metals used in automotive applications to reduce vehicle weight. Crystallographic texture engineering through a combination of intelligent processing and alloying is a powerful and effective tool to obtain superior aluminum and magnesium alloys with optimized strength and ductility for automotive applications. In the present article the basic mechanisms of texture formation of aluminum and magnesium alloys during wrought processing are described and the major aspects and differences in deformation and recrystallization mechanisms are discussed. In addition to the crystal structure, the resulting properties can vary significantly, depending on the alloy composition and processing conditions, which can cause drastic texture and microstructure changes. The elementary mechanisms of plastic deformation and recrystallization comprising nucleation and growth and their orientation dependence, either within the homogeneously formed microstructure or due to inhomogeneous deformation, are described along with their impact on texture formation, and the resulting forming behavior. The typical face-centered cubic and hexagonal close-packed rolling and recrystallization textures, and related mechanical anisotropy and forming conditions are analyzed and compared for standard aluminum and magnesium alloys. New aspects for their modification and advanced strategies of alloy design and microstructure to improve material properties are derived

  12. Influence of Mg and Ti on the microstructure and electrochemical performance of aluminum alloy sacrificial anodes

    Institute of Scientific and Technical Information of China (English)

    MA Jingling; WEN Jiuba; LI Xudong; ZHAO Shengli; YAN Yanfu

    2009-01-01

    The experiments focused on the influence of magnesium and titanium as additional alloying elements on the microstructure and electro-chemical behavior of Al-Zn-ln sacrificial anodes. The electrochemical behavior of the aluminum sacrificial anode with 3 wt.% sodium chlo-fide solution was studied by electrochemical impedance spectroscopy (EIS) tests. It was found that a microstructure with few precipitates and refined grains could be achieved by adding 1 wt.% Mg and 0.05 wt.% Ti to the Al-Zn-In alloy, resulting in the improved current capacity and efficiency of the alloy. The equivalent circuit based on the EIS experimental data revealed less corrosion and lower adsorbed corrosion pro-duction on the surface of the aluminum alloy with a combination of 1 wt.% Mg and 0.05 wt.% Ti, which suggested that the corrosion behav-ior seemed to be strongly related to the presence of precipitate particles in the aluminum alloy, and moderate amounts of precipitate particles could be beneficial to the electrochemical performance of the aluminum alloy sacrificial anode.

  13. Effects of Be, Sr, Fe and Mg interactions on the microstructure and mechanical properties of aluminum based aeronautical alloys

    Science.gov (United States)

    Ibrahim, Mohamed Fawzy

    The present work was carried out on a series of heat-treatable aluminum-based aeronautical alloys containing various amounts of magnesium (Mg), iron (Fe), strontium (Sr) and beryllium (Be). Tensile test bars (dendrite arm spacing ~ 24mum) were solutionized for either 5 or 12 hours at 540°C, followed by quenching in warm water (60°C). Subsequently, these quenched samples were aged at 160°C for times up to 12 hours. Microstructural assessment was performed. All heat-treated samples were pulled to fracture at room temperature using a servo-hydraulic tensile testing machine. The results show that Be causes partial modification of the eutectic silicon (Si) particles similar to that reported for Mg addition. Addition of 0.8 wt.% Mg reduced the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, without Sr, a peak corresponding to the formation of a Be-Fe phase (Al8Fe2BeSi) was detected at 611°C. The Be-Fe phase precipitates in a script-like morphology. A new quinary eutectic-like reaction was observed to take place near the end of solidification of high Mg, high Fe, Be-containing alloys. This new reaction is composed mainly of fine particles of Si, Mg2Si, pi-Al 8Mg3FeSi6 and (Be-Fe) phases. The volume fraction of this reaction decreased with the addition of Sr. The addition of Be has a noticeable effect on decreasing the beta-phase length, or volume fraction, this effect may be limited by adding Sr. Beryllium addition also results in the precipitation of the beta-phase in a nodular form, which reduces the harmful effects of these intermetallics on the alloy mechanical properties. Increasing both Mg and Fe levels led to an increase in the amount of the pi-phase; increasing the iron content led to an increase in the volume fraction of the partially soluble beta- and pi-phases, while Mg2Si particles were completely dissolved. The beta-phase platelets were observed to undergo changes in their morphology due to the

  14. Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

    Energy Technology Data Exchange (ETDEWEB)

    Seri, Osami [Muroran it., Hokkaido (Japan)

    2008-06-15

    It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl{sub 3}. The FeAl{sub 3} particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl{sub 3} particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl{sub 3} free surface was an electrochemical treatment such as cathodic current density of -2 kAm{sup -2} in a 20-30 mass% HNO{sub 3} solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl{sub 3} free particles are examined in a 0.1 kmol/m{sup 3} NaCl solution. It is found that aluminum with free FeAl{sub 3} particles shows higher corrosion resistance than aluminum with FeAl{sub 3} particles.

  15. Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

    International Nuclear Information System (INIS)

    It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl3. The FeAl3 particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl3 particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl3 free surface was an electrochemical treatment such as cathodic current density of -2 kAm-2 in a 20-30 mass% HNO3 solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl3 free particles are examined in a 0.1 kmol/m3 NaCl solution. It is found that aluminum with free FeAl3 particles shows higher corrosion resistance than aluminum with FeAl3 particles

  16. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    Science.gov (United States)

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

    1986-01-01

    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  17. Environmental behavior and stress corrosion characteristics of nano/sub-micron E950 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Aghion, Eli; Guinguis, Inbar [Department of Materials Engineering, Ben-Gurion University of the Negev Beer-Sheva (Israel)

    2009-11-15

    The corrosion performance and stress corrosion resistance of E950 Aluminum alloy with nano/sub-micron structure were evaluated in 3.5% NaCl solution. The results obtained indicated that the corrosion and stress corrosion resistance of E950 alloy were relatively reduced compared to that of the conventional coarse-grained alloy (Al-4.65%Mg). In particular, the inherently improved ultimate tensile strength of E950 alloy was significantly decreased under stress corrosion conditions. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. 铝及铝合金先进焊接技术%Advanced Welding Technology of Aluminum and Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    杨芙; 吕文桂; 张文明

    2012-01-01

    The weldability of aluminum and aluminum alloy and the causes and solutions of welding defects, such as porosity, hot cracks, etc., were analyzed. The research and application of several advanced welding technology for aluminum and aluminum alloy, such as laser welding, electron beam welding, variable polarity plasma arc welding, friction stir welding, etc., were discussed. The development status and tendency for the next few years welding were simply analyzed.%分析了铝及铝合金的焊接性及其在焊接过程中易出缺陷(气孔、热裂纹等)的原因和解决措施;探讨了铝及铝合金的几种先进焊接工艺(激光焊、电子束焊、变极性等离子电弧焊、搅拌摩擦焊等)的研究现状及其应用;分析了铝及铝合金焊接技术的发展状况以及未来几年的前景.

  19. A mixture of massive and feathery microstructures of Ti48Al2Cr2Nb alloy by high undercooled solidification

    International Nuclear Information System (INIS)

    A mixture of massive and feathery microstructures was observed in Ti48Al2Cr2Nb alloy subjected to the undercooled solidification rather than the heat treatments in most cases. Double recalescence events and primary β solidification confirmed that massive γ phase did not directly nucleate from the undercooled melt but formed during the solid-state transformations. It is believed that small white areas (aluminium-poor) along lamellar grain boundaries may be closely related to the formation of massive γ phase and feathery γ phase. High dislocation density and stacking faults were detected in massive γ phase by transmission electron microscopy. The high energy of defects and undercooling in the solid state phase transformation can provide sufficiently high driving force for the nucleation of massive γ phase. - Graphical abstract: Display Omitted - Highlights: • A mixture of massive and feathery microstructures was observed. • Massive γ formed during the solid-state transformations. • Defects and undercooling provide driving force for the nucleation of massive γ

  20. Welding phenomena of aluminum-copper alloy in electron beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Nogi, K.; Sumi, Y.; Aoki, Y.; Yamamoto, T.; Fujii, H. [Osaka Univ., Ibaraki (Japan). Joining and Welding Res. Inst.

    2000-07-01

    Electron beam welding of an aluminum-copper alloy (2219) was performed using a small-sized electron beam welding apparatus under microgravity and in a high vacuum. The effect of gravity on various welding phenomena and the effect of the aluminum oxide film on the formation of bubbles were investigated. A much flatter weld bead is formed in the microgravity environment than in the terrestrial environment. When an aluminum alloy is exposed to atomic oxygen, the thickness of the aluminum oxide film increases and porosity after welding also increases. It is thought that the porosity is formed by the Al{sub 2}O gas through the reaction between Al{sub 2}O{sub 3} and Al. (orig.)

  1. Development of boronated aluminum alloy for basket of cask for nuclear spent fuel

    International Nuclear Information System (INIS)

    Since 1980's Mitsubishi Heavy Industries, Ltd. (MHI) has been contributing to develop metal cask technologies for utilities and competent authorities in Japan, and have established transport and storage cask design ''MSF series'' which realizes higher payload and reliability for long term storage. MSF series transport and storage cask uses new-developed boronated aluminum as basket material. This boronated aluminum has been developed to improve characteristics of material. To achieve this object, powder metallurgy method has been adopted for manufacturing boronated material. It is well known that this method provides excellent characteristics for the material and this boronated aluminum alloy has obtained excellent both mechanical and neutron absorbing characteristics. In addition, in order to maintain material properties for long-term use this boronated material is not strengthened by aging treatment. This paper summarizes an outline of the boronated aluminum alloy for basket assemblies by powder metallurgy. (author)

  2. Experimental study of corrosion behavior for burnished aluminum alloy by EWF, EBSD, EIS and Raman spectra

    International Nuclear Information System (INIS)

    The effect of burnish process on 2024 aluminum alloy was studied by electron work function and electron backscattered diffraction (EBSD). Moreover, the corrosion resistance of thin passive films formed on 2024 aluminum alloy in borate buffer solutions was studied by the electrochemical impedance spectroscopy (EIS), the Mott–Schottky plots and the galvanostatic techniques. The composition of passive films was analyzed by Raman spectra. The results obtained indicated that the impedance increased due to burnish and this was attributed to decreased electron work function and higher current efficiency in the burnished aluminum alloy which led to thicker passive films. It was further supported by Raman spectra experiment. Moreover, the donor and acceptor concentration of passive films and their the semiconductor type have changed due to burnish.

  3. Numerical and experimental study of phase transformation in resistance spot welding of 6082 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    TANG Xinxin; SHA Ping; LUO Zhen; LUO Baofa

    2009-01-01

    Resistance spot welding(RSW) is an efficient and convenient joining process for aluminum alloy sheet assembly. Because the RSW has the character of energy concentration and quick cooling rate, the microstructure transformation of the base metal can be confined in the least limit. The material properties and the welding parameters have significant effects on thequality of the nugget. To predict the microstructure evolution in the melted zone and the heat-affected zone, an electrical, thermal, metallurgical and mechanical coupled finite element model is described and applied to simulate the welding process of the 6082 aluminum alloy. Experimental tests are also carried out. The comparison between experimental and numerical results shows that the adopted model is effective enough to well interpret and predict some important phenomena in terms of the phase transformation in spot welding of 6082 aluminum alloy.

  4. Investigation of Stress Corrosion Cracking Initiation of 7A52 Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    LI Qi; ZHAO Junjun; ZHANG Ping

    2012-01-01

    The stress corrosion cracking(SCC) behaviour of 7A52 aluminum alloy in air and in 3.5%NaCl solution was researched by slow strain rate test(SSRT) and SEM-EDS.The SCC susceptibility was estimated with the loss of the reduction in area.The experimental results indicate that the SCC susceptibility of 7A52 aluminum alloy in 3.5% chloride solution is the highest at strain rate of 1 × 10-6 s-1.The lowest one is under the condition of 1 × 10-5 s-1.Stress concentration and anode dissolving around Al-Fe-Mn intermetallics initiate micropores which will result in microcracks.The existence of intermetallics in the microstructure may play an important role in understanding the SCC initiation mechanisms of 7A52 aluminum alloy.

  5. Experimental study of corrosion behavior for burnished aluminum alloy by EWF, EBSD, EIS and Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Jinlong, Lv, E-mail: ljlhit@126.com [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China); Hongyun, Luo, E-mail: luo7128@163.com [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China); Jinpeng, Xie [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China)

    2013-05-15

    The effect of burnish process on 2024 aluminum alloy was studied by electron work function and electron backscattered diffraction (EBSD). Moreover, the corrosion resistance of thin passive films formed on 2024 aluminum alloy in borate buffer solutions was studied by the electrochemical impedance spectroscopy (EIS), the Mott–Schottky plots and the galvanostatic techniques. The composition of passive films was analyzed by Raman spectra. The results obtained indicated that the impedance increased due to burnish and this was attributed to decreased electron work function and higher current efficiency in the burnished aluminum alloy which led to thicker passive films. It was further supported by Raman spectra experiment. Moreover, the donor and acceptor concentration of passive films and their the semiconductor type have changed due to burnish.

  6. Two-dimensional phase-field study of competitive grain growth during directional solidification of polycrystalline binary alloy

    Science.gov (United States)

    Takaki, Tomohiro; Ohno, Munekazu; Shibuta, Yasushi; Sakane, Shinji; Shimokawabe, Takashi; Aoki, Takayuki

    2016-05-01

    Selections of growing crystals during directional solidification of a polycrystalline binary alloy were numerically investigated using two-dimensional phase-field simulations. To accelerate the simulations, parallel graphics processing unit (GPU) simulations were performed using the GPU-rich supercomputer TSUBAME2.5 at the Tokyo Institute of Technology. Twenty simulations with a combination of five sets of different seed orientation distributions and four different temperature gradients covering dendritic and cellular growth regions were performed. The unusual grain selection phenomenon, in which the unfavorably oriented grains preferentially grow instead of the favorably oriented grains, was observed frequently. The unusual selection was more remarkable in the cellular structure than in the dendritic structure.

  7. Development of technology of complex aluminum-silicon-chrome alloy with utilization of off grade raw materials

    OpenAIRE

    A. Mekhtiev; Ye. Shabanov; А. Issagulov; S. Baissanov; А. Baissanov; D. Issagulova

    2015-01-01

    Experimental studies on obtaining a complex aluminum-silicon-chrome alloy (FASCh) from Karaganda high-ash coals and high-carbon ferrochromefines were carried out. A method for smelting low-carbon ferrochrome using aluminum-silicon-chrome alloy as a reductant is suggested.

  8. Effect of Heat Treatment on the In-Plane Anisotropy of As-Rolled 7050 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Huie Hu

    2016-04-01

    Full Text Available Tensile tests were conducted on both as-quenched and over-aged 7050 aluminum alloy to investigate the effect of heat treatment on the in-plane anisotropy of as-rolled 7050 aluminum alloy. The results showed that the tensile direction has limited effect on mechanical properties of the as-quenched 7050 aluminum alloy. The in-plane anisotropy factors (IPA factor of tensile strength, yield strength, and elongation in as-rolled 7050 aluminum alloy fluctuate in the vicinity of 5%. The anisotropy of the as-quenched 7050 aluminum alloy is mainly affected by the texture according to single crystal analysis based on the Schmid factor method. Besides, the IPA factor of the elongation in the over-aged 7050 aluminum alloy reaches 11.6%, illustrating that the anisotropy of the over-aged 7050 aluminum alloy is more prominent than that of the as-quenched. The occurrence of the anisotropy in the over-aged 7050 aluminum alloy is mainly attributed to the microstructures. which are characterized by visible precipitate free zones (PFZs and coarse precipitates in (subgrain boundaries.

  9. Galvanic compatibility of corrosion protective coatings with AA7075 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lodhi, Z.F.; Hamer, W.J. [Netherlands Institute for Metals Research (NIMR), Mekelweg 2, 2628 CD Delft (Netherlands); Mol, J.M.C.; Wit, J.H.W. de [Delft University of Technology, Department of Materials Science and Engineering, Mekelweg 2, 2628 CD Delft (Netherlands); Terryn, H. [Netherlands Institute for Metals Research (NIMR), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Metallurgy, Electrochemistry and Materials Science, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium)

    2008-04-15

    The galvanic compatibility of aerospace aluminum alloy AA7075 with cadmium (Cd), zinc (Zn), and zinc-cobalt-iron (Zn-Co-Fe, 32-37%Co and 1%Fe) alloys was investigated. A comparison of open circuit potential [OCP vs. saturated calomel electrode (SCE)] measurements in 0.6 mM NaCl showed that all coatings would act anodically to AA7075 with an exception of Zn-Co-Fe (37%Co + 1%Fe) alloy which was electropositive to AA7075. During the zero resistance ammetry (ZRA) measurement in 0.6 M NaCl electrolyte the coupled OCP and current density were measured during 7 days of immersion and both Zn and Cd acted anodic and thus sacrificial to AA7075. Galvanic coupling of AA7075 with (37%Co + 1%Fe) Zn-Co-Fe alloy resulted in the consequent dissolution of the AA7075 aluminum alloy. In contrast, Zn-Co-Fe (32%Co + 1%Fe) alloy was found to be anodic to AA7075 during the first 26 h of immersion but after dezincification and cobalt enrichment at the surface became cathodic to the AA7075 aluminum alloy. During coupling with Zn, some pitting was also observed on AA7075. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  10. Solidification of Au-Cu-Si alloys investigated by a combinatorial approach

    International Nuclear Information System (INIS)

    Composition libraries of Au-Cu-Si films comprising 800 composition patches were fabricated through co-sputtering deposition from elemental targets. The gold composition varies between 47% (compositions are in atomic percentage) and 81%, copper between 8% and 40%, and silicon between 6% and 36% within the library. We designed and used a high-throughput optical characterization method to detect melting and solidification based on changes in the film’s contrast; further microscopy characterization reveals the microstructure. This approach reveals the composition dependence of the nucleation temperature and primary phase, which allows us to draw conclusions about glass forming ability and to identify bulk metallic glass forming compositions. Our solidification results suggest that the best glass forming composition coincides with the composition at which a transition from one primary phase to another occurs. We show that in general this transition is not at the eutectic composition but at the lowest nucleation temperature.

  11. Radial solidification of Al-Si alloys in the presence of a rotating magnetic field

    International Nuclear Information System (INIS)

    We study the flow field during the radial solidification of an Al-7wt pct Si melt inside a cylindrical cavity with cooled side walls which is placed in a rotating magnetic field (RMF). The solidification process is simulated by means of a continuum model which is implemented in a code which solves the axisymmetric Navier-Stokes equations. We first analyze the start-up of the buoyancy-driven convection driven by the radial heat flux in absence of the RMF. We show that the initial large vortex breaks up into three smaller one. The resulting radial temperature profiles are compared with experimental data. Second, we study how the vortex structure is modified by the application of small RMF's.

  12. Competitive growth of different phases in eutectic alloys under directional solidification

    Institute of Scientific and Technical Information of China (English)

    LI; Shuangming; MA; Bole; LI; Xiaoli; LIU; Lin; FU; Hengzhi

    2005-01-01

    By comparisons of interface growth temperatures of different phases in eutectic systems, competitive growth between the primary phase, halo structure and coupled eutectic has been discussed. The compositions for the formation of coupled eutectic have been discussed at the coexisting with the primary phase in eutectic under directional solidification. Solidification conditions, such as growth rate and composition required for the formation of the primary phase, halo structure and coupled eutectic have been proposed. Numerical calculation results show that no halo structure formed in directionally solidified Sn-Pb eutectic, but in Al-Si eutectic, competitive growth structures of the primaryβ-Si phase,α-Al halo structure and coupled eutectic (α+β) may exist at the hypereutectic composition between 12.6% and 25% Si. The calculated results of Al-Si eutectic fit in with the reported experiment results.

  13. Microscopic analysis of effect of shot peening on corrosion fatigue behavior of aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Cheon; Cheong, Seong Kyun [Seoul Nat' l Univ. of Science and Technology, Seoul (Korea, Republic of)

    2012-11-15

    The object of this study considers corrosion fatigue improvement of 7075-T6 aluminum by using shot peening treatment on 3.5% NaCl solution at room temperature. Aluminum alloy is generally used in aerospace structural components because of the light weight and high strength characteristics. Many studies have shown that an aluminum alloy can be approximately 50% lighter than other materials. Mostly, corrosion leads to earlier fatigue crack propagation under tensile conditions and severely reduces the life of structures. Therefore, the technique to improve material resistance to corrosion fatigue is required. Shot peening technology is widely used to improve fatigue life and other mechanical properties by induced compressive residual stress. Even the roughness of treated surface causes pitting corrosion, the compressive residual stress, which is induced under the surface layer of material by shot peening, suppersses the corrosion and increases the corrosion resistance. The experimental results for shot peened specimens were compared with previous work for non treated aluminum alloy. The results show that the shot peening treatment affects the corrosion fatigue improvement of aluminum alloys and the induced compressive residual stress by shot peening treatment improves the resistance to corrosion fatigue.

  14. TIG welding of aluminum alloys for the APS storage ring - a UHV application

    International Nuclear Information System (INIS)

    The Advanced Photon Source (APS) incorporates a 7-GeV positron storage ring 1104 meters in circumference. The storage ring vacuum system is designed to maintain a pressure of 1 nTorr or less with a circulating current of 300 mA to enable beam lifetimes of greater than 10 hours. The vacuum chamber is an aluminum extrusion of 6063T5 alloy. There are 235 separate aluminum vacuum chambers in the storage ring connected by stainless steel bellows assemblies. Aluminum was chosen for the vacuum chamber because it can be economically extruded and machined, has good thermal conductivity, low thermal emissivity, a low outgassing rate, low residual radioactivity, and is non-magnetic. The 6063 aluminum-silicon-magnesium alloy provides high strength combined with good machining and weldability characteristics. The extrusion process provides the interior surface finish needed for the ultrahigh vacuum (UHV) environments There are six different vacuum chambers with the same extrusion cross section. The average vacuum chamber length is 171.6 inches. The extruded vacuum chambers are welded to flange assemblies made up of machined 2219 aluminum alloy pieces and 2219 aluminum vacuum flanges from a commercial source

  15. TIG welding of aluminum alloys for the APS storage ring - a UHV application

    Energy Technology Data Exchange (ETDEWEB)

    Goeppner, G.A.

    1996-05-29

    The Advanced Photon Source (APS) incorporates a 7-GeV positron storage ring 1104 meters in circumference. The storage ring vacuum system is designed to maintain a pressure of 1 nTorr or less with a circulating current of 300 mA to enable beam lifetimes of greater than 10 hours. The vacuum chamber is an aluminum extrusion of 6063T5 alloy. There are 235 separate aluminum vacuum chambers in the storage ring connected by stainless steel bellows assemblies. Aluminum was chosen for the vacuum chamber because it can be economically extruded and machined, has good thermal conductivity, low thermal emissivity, a low outgassing rate, low residual radioactivity, and is non-magnetic. The 6063 aluminum-silicon-magnesium alloy provides high strength combined with good machining and weldability characteristics. The extrusion process provides the interior surface finish needed for the ultrahigh vacuum (UHV) environments There are six different vacuum chambers with the same extrusion cross section. The average vacuum chamber length is 171.6 inches. The extruded vacuum chambers are welded to flange assemblies made up of machined 2219 aluminum alloy pieces and 2219 aluminum vacuum flanges from a commercial source.

  16. Effect of Electromagnetic Frequency on Microstructures of Continuous Casting Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The relationship between electromagnetic frequency and microstructures of continuous casting aluminum alloyswas studied. 7075 aluminum alloy ingot of 100 mm in diameter was produced by electromagnetic continuouscasting process, the microstructures of as-cast ingot was examined by scanning electron microscopy (SEM) equippedwith energy dispersive spectrometer (EDS). The results showed that electromagnetic frequency greatly influencedsegregation and microstructures of as-cast ingot, and product quality can be guaranteed by the application of aproper frequency. Electromagnetic frequency plays a significant role in solute redistribution; Iow frequency is moreefficient for promoting solution of alloying elements.

  17. Pore formation during C.W.Nd: YAG laser welding of aluminum alloys for automotive applications

    International Nuclear Information System (INIS)

    Pore formation is an important concern in laser welding of automotive aluminum alloys. This paper investigates the influence of the laser beam defocusing on pore formation during continuous wave Nd:YAG laser welding of aluminum automotive alloys 5182 and 5754. It was found that the instability of the keyhole during welding was a dominant cause of pore formation while hydrogen rejection played an insignificant role. The defocusing of the laser beam greatly affected the stability of the keyhole. Finally, the mechanism of the collapse of the keyhole and pore formation is proposed. (Author) 45 refs

  18. Influence of Density on Compressive Properties and Energy Absorption of Foamed Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    WEI Peng; LIU Lin

    2007-01-01

    The foamed aluminum alloys with different densities were fabricated by melt foaming technique. The compressive properties and energy absorption of the foamed aluminum alloy with different densities were analyzed. The results reveal that the compressive stress-strain curves follow the typical behavior of cellular foams with three deformation stages. Under the same strain, the energy absorption capability decreases with the decrease of density. However, with increasing the strain, the energy absorption efficiency of foamed metal increases initially and then decreases. The lower the density, the longer the plateau region, within the range of high strain, the energy absorption efficiency is always high.

  19. Power ultrasound irradiation during the alkaline etching process of the 2024 aluminum alloy

    Science.gov (United States)

    Moutarlier, V.; Viennet, R.; Rolet, J.; Gigandet, M. P.; Hihn, J. Y.

    2015-11-01

    Prior to any surface treatment on an aluminum alloy, a surface preparation is necessary. This commonly consists in performing an alkaline etching followed by acid deoxidizing. In this work, the use of power ultrasound irradiation during the etching step on the 2024 aluminum alloy was studied. The etching rate was estimated by weight loss, and the alkaline film formed during the etching step was characterized by glow discharge optical emission spectrometry (GDOES) and scanning electron microscope (SEM). The benefit of power ultrasound during the etching step was confirmed by pitting potential measurement in NaCl solution after a post-treatment (anodizing).

  20. Study on quality of resistance spot welded aluminum alloys under various electrode pressures

    Institute of Scientific and Technical Information of China (English)

    San-san AO; Zhen LUO; Xin-xin TANG; Lin-shu ZHOU; Shu-xian YUAN; Rui WANG; Kai-lei SONG; Xing-zheng BU; Xiao-yi LI; Zhi-qing XUE

    2009-01-01

    The electrode force is One of the main parameters in resistance spot welding (RSW). It is very important to guarantee the quality of aluminum alloys and determine whether the electrode pressure is stable or adjustable in the welding process. With the drive set of a servo-motor, we conduct the RSW tests and tensile shear tests on the 5052 aluminum alloy sheets. Results of these tests show that all variable pressure curves are suitable for spot welding, and all have their own rules in affecting the tensile strength of the spot welded joints.

  1. Degradation assesment of aluminum alloy 6061-T6 using ultrasonic attenuation measurements

    International Nuclear Information System (INIS)

    Ultrasonic methods are widely used to degradation assesment. Remaining life cycle of metal can be estimated by ultrasonic parameters because ultrasonic velocity and attenuation are affected by change of material properties with accumulated fatigue in the metal. Therefore, in this study, we will estimate overall change of material properties by 2D C scan image. Fatigued aluminum alloy 6061-T6 samples from 0 to 85% were prepared for evaluating fatigue life cycle. Also, degraded image of materials using attenuation is proposed to estimate degree of material degradation for determining degraded area of fatigued samples. Finally, we will predicts process pf degradation with measured attenuation of fatigued aluminum alloy 6061-T6 samples

  2. Effect of Porosity and Cell Size on the Dynamic Compressive Properties of Aluminum Alloy Foams

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The dynamic mechanical properties of open-cell aluminum alloy foams with different relative densities and cell sizeshave been investigated by compressive tests. The strain rates varied from 700 s-1 to 2600 s-1. The experimentalresults showed that the dynamic compressive stress-strain curves exhibited a typical three-stage behavior: elastic,plateau and densification. The dynamic compressive strength of foams is affected not only by the relative densitybut also by the strain rate and cell size. Aluminum alloy foams with higher relative density or smaller cell size aremore sensitive to the strain rate than foams with lower relative density or larger cell size.

  3. Niobium-aluminum base alloys having improved, high temperature oxidation resistance

    Science.gov (United States)

    Hebsur, Mohan G. (Inventor); Stephens, Joseph R. (Inventor)

    1991-01-01

    A niobium-aluminum base alloy having improved oxidation resistance at high temperatures and consisting essentially of 48%-52% niobium, 36%-42% aluminum, 4%-10% chromium, 0%-2%, more preferably 1%-2%, silicon and/or tungsten with tungsten being preferred, and 0.1%-2.0% of a rare earth selected from the group consisting of yttrium, ytterbium and erbium. Parabolic oxidation rates, k.sub.p, at 1200.degree. C. range from about 0.006 to 0.032 (mg/cm.sup.2).sup.2 /hr. The new alloys also exhibit excellent cyclic oxidation resistance.

  4. Mechanical characteristic of flowing solidification under the extrusion for the mixture of the liquid aluminum with sillimanite particles

    Energy Technology Data Exchange (ETDEWEB)

    Wei Chen [Academy of Armored Force Engineering (China); Jiangsu Fasten Block Corp. (China); Changqing Sun; Yunliang Li [Academy of Armored Force Engineering (China)

    2005-07-01

    According to the theory of liquid metal forging and liquid metal extrusion, a new kind of fabricating method for particles reinforced metallic matrix composite was put forward by author. In this paper, the extrusion process to semisolid thick liquid after the mixture was studied by means of the theoretical analysis and experimental methods. Mechanical characteristics of solidification during flowing and plastic deformation during solidification of the composite were found. So the base was built up for selecting technology parameters and for building a stable process. (orig.)

  5. Microstructure and properties of 2618-Ti heat resistant aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    王建华; 易丹青; 王斌

    2003-01-01

    The mechanical properties of alloy 2618 with 0.5%(mass fraction) titanium and its microstructures in different states such as as-cast and quenching-aging were investigated. Titanium was added into the alloy with Al-5%Ti master alloy that was extruded severely. Al3Ti particles in the microstructure of cast alloy 2618-Ti are very small because those of master alloy are also small. When titanium is used as an alloying element, it does not affect the morphology of Al9FeNi phase in cast alloy, but decreases the grain size of as-cast alloy remarkably. The grain size of quenching-aging alloy 2618 decreases apparently due to the existence of a great deal of dispersive Al3Ti particles. Adding 0.5%Ti has no effect on the room temperature tensile properties of alloy 2618, but apparently increases the elevated temperature instantaneous tensile properties and that of the alloy which is exposed at 250 ℃ for 100 h.

  6. Cryogenic properties of aluminum and aluminum alloys. 1964-March 1980 (citations from the NTIS Date Base). Report for 1964-March 1980

    International Nuclear Information System (INIS)

    Citations of Federally-funded research include studies on the cryogenic properties of aluminum and its alloys used in superconducting machinery, magnets, space technology, and nuclear reactors. Electrical properties, fatigue, deformation, and welds are included

  7. ARTIFICIAL NEURAL NETWORK MODEL OF CONSTITUTIVE RELATIONSHIP FOR 2A70 ALUMINUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    F. Liu; D.B. Shan; Y. Lu; Y.Y. Yang

    2005-01-01

    The hot deformation behavior of 2A70 aluminum alloy was investigated by means of isothermal compression tests performed on a Gleeble-1500 thermal simulator over a wide range of temperatures 360-480℃ with strain rates of 0.01-1s-1 and the largest deformation of 60%, and the true stress of the material was obtained under the above-mentioned conditions. The experimental results shows that 2A70 aluminum alloy is a kind of aluminum alloy with the property of dynamic recovery; its flow stress declines with the increase of temperature, while its flow stress increases with the increase of strain rates. On the basis of experiments, the constitutive relationship of the 2A70 aluminum alloy was constructed using a BP artificial neural network. Comparison of the predicted values with the experimental data shows that the relative error of the trained model is less than ±3% for the sampled data while it is less than ±6% for the nonsampled data. It is evident that the model constructed by BP ANN can accurately predict the flow stress of the 2A70 alloy.

  8. A Parametric Analysis of CO2 Laser Heat Absorption Profile of 5083 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available Aluminum alloys are amongst the most difficult everyday metals that can be welded using the laser welding process. For this reason, high power density lasers are needed to weld these alloys because they require higher thermal diffusivity to form a key hole than would be needed for other metals such as steel. This means that more heat wouldhave to be applied while welding aluminum alloys than would be needed to weld steel to achieve a satisfactory coupling effect. The heat input generated from laser welding is affected by the absorptivity coefficient, the welding speed and the time spent. Once the optimum heat input is attained, it is expected to create less heat distortion, its energy is more concentrated within the weld area and deep weld penetration is achieved. Determining optimum values of welding parameters would lead to acceptable weld quality. In this study, the heat absorption profile of a CO2 laser welding of 5083 aluminum alloy was investigated using the models proposed by Bramson in 1968 and Okon et al in 2002. The 4mm thick aluminum alloy investigated was as received from the vendors. The calculated laser beam absorptivity coefficient, irradiance and boiling temperature were 0.12, 2.3 x 106 Wcm-2 and 2482oC respectively. These calculated values compared well with reported values in other literature.

  9. Quantitative analysis of impurities in aluminum alloys by laser-induced breakdown spectroscopy without internal calibration

    Institute of Scientific and Technical Information of China (English)

    LI Hong-kun; LIU Ming; CHEN Zhi-jiang; LI Run-hua

    2008-01-01

    To develop a fast and sensitive alloy elemental analysis method, a laser-induced breakdown spectroscopy(LIBS) system was established and used to carry out quantitative analysis of impurities in aluminum alloys in air at atmospheric pressure. A digital storage oscilloscope was used as signal recording instrument, instead of traditional gate integrator or Boxcar averager, to reduce the cost of the whole system. Linear calibration curves in the concentration range of 4×10-5-10-2 are built for Mg, Cr, Mn, Cu and Zn using absolute line intensity without internal calibrations. Limits of detection for these five elements in aluminum alloy are determined to be (2-90)×10-6. It is demonstrated that LIBS can provide quantitative trace elemental analysis in alloys even without internal calibration. This approach is easy to use in metallurgy industries and relative research fields.

  10. Evaluation of Aluminum Alloy 2050-T84 Microstructure and Mechanical Properties at Ambient and Cryogenic Temperatures

    Science.gov (United States)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320degF. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  11. Evaluation of Aluminum Alloy 2050-T84 Microstructure Mechanical Properties at Ambient and Cryogenic Temperatures

    Science.gov (United States)

    Hafley, Robert A.; Domack, Marcia S.; Hales, Stephen J.; Shenoy, Ravi N.

    2011-01-01

    Aluminum alloy 2050 is being considered for the fabrication of cryogenic propellant tanks to reduce the mass of future heavy-lift launch vehicles. The alloy is available in section thicknesses greater than that of the incumbent aluminum alloy, 2195, which will enable the designs with greater structural efficiency. While ambient temperature design allowable properties are available for alloy 2050, cryogenic properties are not available. To determine its suitability for use in cryogenic propellant tanks, tensile, compression and fracture tests were conducted on 4 inch thick 2050-T84 plate at ambient temperature and at -320 F. Various metallurgical analyses were also performed in order to provide an understanding of the compositional homogeneity and microstructure of 2050.

  12. Modeling mechanical properties of cast aluminum alloy using artificial neural network

    International Nuclear Information System (INIS)

    Modeling is widely used to investigate the mechanical properties of engineering materials due to increasing demand of low cost and high strength to weight ratio for many engineering applications. The aluminum casting alloys are cost competitive material and possess the desired properties. The mechanical properties largely depend upon composition of alloys and their processing method. Alloy design involves controlling mechanical properties via optimization of the composition and processing parameters. For optimization the possible root is empirical modeling and its more refined version is the analysis of the wide range of data using ANN (Artificial Neural Networks) modeling. The modeling of mechanical properties of the aluminum alloys are the main objective of present work. For this purpose, some data were collected and experimentally prepared using conventional casting method. A MLP (Multilayer Perceptron) network was developed, which is trained by using the error back propagation algorithm. (author)

  13. A method to study the history of a double oxide film defect in liquid aluminum alloys

    Science.gov (United States)

    Raiszadeh, R.; Griffiths, W. D.

    2006-12-01

    Entrained double oxide films have been held responsible for reductions in mechanical properties in aluminum casting alloys. However, their behavior in the liquid metal, once formed, has not been studied directly. It has been proposed that the atmosphere entrapped in the double oxide film defect will continue to react with the liquid metal surrounding it, perhaps leading to its elimination as a significant defect. A silicon-nitride rod with a hole in one end was plunged into liquid aluminum to hold a known volume of air in contact with the liquid metal at a constant temperature. The change in the air volume with time was recorded by real-time X-ray radiography to determine the reaction rates of the trapped atmosphere with the liquid aluminum, creating a model for the behavior of an entrained double oxide film defect. The results from this experiment showed that first oxygen, and then nitrogen, was consumed by the aluminum alloy, to form aluminum oxide and aluminum nitride, respectively. The effect of adding different elements to the liquid aluminum and the effect of different hydrogen contents were also studied.

  14. Application of a Pore Fraction Hot Tearing Model to Directionally Solidified and Direct Chill Cast Aluminum Alloys

    Science.gov (United States)

    Dou, Ruifeng; Phillion, A. B.

    2016-08-01

    Hot tearing susceptibility is commonly assessed using a pressure drop equation in the mushy zone that includes the effects of both tensile deformation perpendicular to the thermal gradient as well as shrinkage feeding. In this study, a Pore Fraction hot tearing model, recently developed by Monroe and Beckermann (JOM 66:1439-1445, 2014), is extended to additionally include the effect of strain rate parallel to the thermal gradient. The deformation and shrinkage pore fractions are obtained on the basis of the dimensionless Niyama criterion and a scaling variable method. First, the model is applied to the binary Al-Cu system under conditions of directional solidification. It is shown that for the same Niyama criterion, a decrease in the cooling rate increases both the deformation and shrinkage pore fractions because of an increase in the time spent in the brittle temperature region. Second, the model is applied to the industrial aluminum alloy AA5182 as part of a finite element simulation of the Direct Chill (DC) casting process. It is shown that an increase in the casting speed during DC casting increases the deformation and shrinkage pore fractions, causing the maximum point of pore fraction to move towards the base of the casting. These results demonstrate that including the strain rate parallel to the thermal gradient significantly improves the predictive quality of hot tearing criteria based on the pressure drop equation.

  15. Atmospheric Corrosion Behavior of 2A12 Aluminum Alloy in a Tropical Marine Environment

    OpenAIRE

    Zhongyu Cui; Xiaogang Li; Huan Zhang; Kui Xiao; Chaofang Dong; Zhiyong Liu; Liwei Wang

    2015-01-01

    Atmospheric corrosion behavior of 2A12 aluminum alloy exposed to a tropical marine environment for 4 years was investigated. Weight loss of 2A12 alloy in the log-log coordinates can be well fitted with two linear segments, attributing to the evolution of the corrosion products. EIS results indicate that the corrosion product layer formed on the specimens exposed for 12 months or longer presents a good barrier effect. Corrosion morphology changes from pitting corrosion to severe intergranular ...

  16. A Study of the Quench Sensitivity of 6061-T6 and 6069-T6 Aluminum Alloys

    OpenAIRE

    M. E. Kassner; P. Geantil; Li, X

    2011-01-01

    The purpose of this study is to investigate the quench sensitivity of the mechanical properties of 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delay time at various temperatures between 200–500°C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference. This study also provides increased data on the quench sensitivity of the traditional alloy, 6061-T6.

  17. EBSD characterization of deformation in high strain rate application aluminum alloys

    OpenAIRE

    Kozmel, Thomas; Vural, Murat; Tin, Sammy

    2014-01-01

    Advances in materials characterization tools and techniques are contributing to an improved physics based understanding pertaining to the characteristic behavior of engineering alloys. Aluminum alloys, such as 2139, 2519, 5083, and 7039 are commonly used for lightweight armor applications where resistance to high strain rate deformation is paramount. Failure of these materials is often attributed to the onset of shear band formation. This study was aimed at complimenting the constituent predi...

  18. Calculation of Liquidus Temperature for Aluminum and Magnesium Alloys Applying Method of Equivalency

    OpenAIRE

    Mile B. Djurdjević; Srećko Manasijević; Zoran Odanović; Natalija Dolić

    2013-01-01

    The purpose of this paper is to develop a mathematical equation, which will be able to accurately predict the liquidus temperature of various aluminum and magnesium cast alloys on the basis of their known chemical compositions. An accurate knowledge of liquidus temperature permits a researcher to predict a variety of physical parameters pertaining to a given alloy. The analytical expressions presented in this paper are based on the “method of equivalency.” According to this concept, the influ...

  19. TESTING OF ALUMINUM-SILICON ALLOYS MECHANICAL PROPERTIES ON SEPARATELY CASTED SPECIMENS

    OpenAIRE

    Krushenko, G.

    2010-01-01

    The mechanical properties of aluminum alloys before casting into moulds were determined on separately casted control specimens casted in horizontal or vertical forms. A comparison of the mechanical properties (tensile strength t, elongation 8, hardness HB) of 12-mm-diameter individually casted of AK7ch alloy control specimens and its density in the solid state (p) showed that it is necessary to use specimens casted in a horizontal mold for evaluation of castings quality. It was estimated that...

  20. Dynamic process of angular distortion between aluminum and titanium alloys with TIG welding

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; LIANG Zhen-xin; ZHANG Jian-xun

    2008-01-01

    The dynamic process of welding angular distortion in the overlaying welding of 5A12 aluminum alloy and BT20 titanium alloy was investigated. Information of dynamic distortion was got via self-made welding dynamic measuring system. Research results show that the characteristics of dynamic distortions at various positions of the plate edge parallel to the weld of 5A12 and BT20 alloy are different. Comparison between 5A12 and BT20 alloy shows that transverse shrinkage and downward longitudinal bending are main factors influencing the dynamic angular distortion processes of 5A12 and BT20 alloy under welding heat input of 0.32 kJ/mm. The angular distortion of 5A12 alloy is completely inversed with welding heat input increasing to 0.4 kJ/mm, and the position of weld center and buckling distortion become the primary factors.

  1. The influence of the parameters of lost foam process on the quality of aluminum alloys castings

    Directory of Open Access Journals (Sweden)

    Aćimović-Pavlović Zagorka

    2010-01-01

    Full Text Available This paper presents the research results of application of Lost foam process for aluminum alloys castings of a simple geometry. The process characteristic is that patterns and gating of moulds, made of polymers, stay in the mould till the liquid metal inflow. In contact with the liquid metal, pattern intensely and in relatively short time decomposes and evaporates, which is accompanied by casting crystallization. As a consequence of polymer pattern decomposition and evaporation a great quantity of liquid and gaseous products are produced, which is often the cause of different types of casting errors. This paper presents the results of a research with a special consideration given to detecting and analyzing the errors of castings. In most cases the cause of these errors are defects of polymer materials used for evaporable patterns production, as well as defects of materials for refractory coatings production for polymer patterns. The researches have shown that different types of coatings determine properties of the obtained castings. Also, the critical processing parameters (polymer pattern density, casting temperature, permeability of refractory coating and sand, construction of patterns and gating of moulds significantly affect on castings quality. During the research a special consideration was given to control and optimization of these parameters with the goal of achieving applicable castings properties. The study of surface and internal error of castings was performed systematically in order to carry out preventive measures to avoid errors and minimize production costs. In order to achieve qualitative and profitable castings production by the method of Lost foam it is necessary to reach the balance in the system: evaporable polymer pattern - liquid metal - refractory coating - sandy cast in the phase of metal inflow, decomposition and evaporation of polymer pattern, formation and solidification of castings. By optimizing the processing

  2. MICROSTRUCTURE OF Mg-6.4Zn-1.1Y ALLOY FABRICATED BY RAPID SOLIDIFICATION AND RECIPROCATING EXTRUSION

    Institute of Scientific and Technical Information of China (English)

    Z.M. Zhang; C.J. Xu; X.F. Guo

    2008-01-01

    In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1 Y magnesium alloy with a thickness of 50-60 um were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by XRD. Phase transformation and its onset temperature were determined by differential thermal analyzer (DTA). The analysis result shows that rapid solidification for Mg-6.4Zn-1.1Y alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in a-Mg solute solution, and impede the formation of Mg3 Y2 Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3 YZn6 quasicrystal formed directly from the melt. The mierostrueture of the flakes consists of the a-Mg solid solution and icosahedral Mg3 YZn6 quasierystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3 YZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases: amagnesium solid solution as matrix and fine icosahedral Mg3 YZn6 quasicrystal which disperses uniformly in the matrix.

  3. X-ray video microscopy studies of irregular eutectic solidification microstructures in Al-Si-Cu alloys

    International Nuclear Information System (INIS)

    In-situ studies of Al-Si eutectic growth has been carried out for the first time by X-ray video microscopy during directional solidification of Al-Si-Cu alloys with and without Sr-additions. The unmodified eutectics showed distinctive non-isothermal growth dynamics, where Si-crystals attained needle-like tip morphologies and progressed under significantly higher undercooling than Al, leading to formation of an irregular eutectic with Si as the leading phase and subsequent nucleation of Al on the Si-surfaces. In the Sr-modified alloys, the eutectic reaction was found to be strongly suppressed, occurring with low nucleation frequencies at undercoolings in the range 10-18 K. In the Cu-enriched melt, the eutectic front was found to attain meso-scale interface perturbations, sometimes evolving into equiaxed cellular rosettes in order to accommodate to the long-range redistribution of Cu from the composite eutectic interface. The eutectic front also attained short-range microscale interface perturbations consistent with characteristics of a fibrous Si growth. However, further improvements in spatial resolution are required in order to study the microscale structure formation in greater detail. Evidence was found in support of Si-nucleation occurring on potent particles suspended in the melt. Yet, both with Sr-modified and unmodified alloys Si precipitation alone was not sufficient to facilitate the eutectic reaction, which apparently required additional undercooling for Al to form on the Si-particles. To what extent nucleation mechanisms in the Cu-enriched systems are transferable to binary or commercial Al-Si alloys remains uncertain. (author)

  4. Grain Refining Performance of SHS Al-50TiC Master Alloys for Commercially Pure Aluminum

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An Al-50wt%TiC composite was directly synthesized by self-propagating high-temperature synthesis (SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminum.The microstructure and grain refining performance of the synthesized master alloy were emphatically investigated.The SHS master alloy only contained submicron TiC particles except for Al matrix.Moreover,TiC particles were relatively free of agglomeration. Grain refining tests show that adding only 0.1 wt% of the master alloys to the aluminum melt could transform the structure of the solidified samples from coarse columnar grains to fine equiaxed grains (average grain size 120μm),and that this grain refining effectiveness could be maintained for almost 1.5h at 1003K. Therefore,it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys, and that it is highly resistant to the grain refining fading encountered with most grain refiners.

  5. Development and Processing Improvement of Aerospace Aluminum Alloys

    Science.gov (United States)

    Lisagor, W. Barry; Bales, Thomas T.

    2007-01-01

    This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

  6. Effects of P+Cr complex modification and solidification conditions on microstructure of hypereutectic Al-Si alloys by wedge-shaped copper mould casting

    Directory of Open Access Journals (Sweden)

    Zhang Haitao

    2014-11-01

    Full Text Available Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic Al-Si alloys. The segregation of primary Si can be inhibited by adding a P+Cr complex modifier and increasing the cooling rate during solidification. The refinement of primary Si particles by P+Cr complex modification is due to the formation of CrSi2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrSi2 particles to the primary Si particles.

  7. Measurements of degree of sensitization (DoS) in aluminum alloys using EMAT ultrasound.

    Science.gov (United States)

    Li, Fang; Xiang, Dan; Qin, Yexian; Pond, Robert B; Slusarski, Kyle

    2011-07-01

    Sensitization in 5XXX aluminum alloys is an insidious problem characterized by the gradual formation and growth of beta phase (Mg(2)Al(3)) at grain boundaries, which increases the susceptibility of alloys to intergranular corrosion (IGC) and intergranular stress-corrosion cracking (IGSCC). The degree of sensitization (DoS) is currently quantified by the ASTM G67 Nitric Acid Mass Loss Test, which is destructive and time consuming. A fast, reliable, and non-destructive method for rapid detection and the assessment of the condition of DoS in AA5XXX aluminum alloys in the field is highly desirable. In this paper, we describe a non-destructive method for measurements of DoS in aluminum alloys with an electromagnetic acoustic transducer (EMAT). AA5083 aluminum alloy samples were sensitized at 100°C with processing times varying from 7days to 30days. The DoS of sensitized samples was first quantified with the ASTM 67 test in the laboratory. Both ultrasonic velocity and attenuation in sensitized specimens were then measured using EMAT and the results were correlated with the DoS data. We found that the longitudinal wave velocity was almost a constant, independent of the sensitization, which suggests that the longitudinal wave can be used to determine the sample thickness. The shear wave velocity and especially the shear wave attenuation are sensitive to DoS. Relationships between DoS and the shear velocity, as well as the shear attenuation have been established. Finally, we performed the data mining to evaluate and improve the accuracy in the measurements of DoS in aluminum alloys with EMAT. PMID:21232777

  8. Precipitation hardening and hydrogen embrittlement of aluminum alloy AA7020

    Indian Academy of Sciences (India)

    Santosh Kumar; T K G Namboodhiri

    2011-04-01

    AA7020 Al–Mg–Zn, a medium strength aluminium alloy, is used in welded structures in military and aerospace applications. As it may be subjected to extremes of environmental exposures, including high pressure liquid hydrogen, it could suffer hydrogen embrittlement. Hydrogen susceptibility of alloy AA7020 was evaluated by slow strain-rate tensile testing, and delayed failure testing of hydrogen-charged specimens of air-cooled, duplexaged, and water-quenched duplex agedmaterials. The resistance to hydrogen embrittlement of the alloy was found to be in the order of air-cooled duplex aged alloy > as-received (T6 condition) > water quenched duplex aged material.

  9. Free energy change of off-eutectic binary alloys on solidification

    Science.gov (United States)

    Ohsaka, K.; Trinh, E. H.; Lin, J.-C.; Perepezko, J. H.

    1991-01-01

    A formula for the free energy difference between the undercooled liquid phase and the stable solid phase is derived for off-eutectic binary alloys in which the equilibrium solid/liquid transition takes place over a certain temperature range. The free energy change is then evaluated numerically for a Bi-25 at. pct Cd alloy modeled as a sub-subregular solution.

  10. Thermal stress-relief treatments for 2219 aluminum alloy are evaluated

    Science.gov (United States)

    1966-01-01

    Evaluation of three thermal stress relief treatments for 2219 aluminum alloy in terms of their effect on residual stress, mechanical properties, and stress corrosion resistance. The treatments are post aging and stress relieving fullscale and subscale parts formed in the aged T81 condition, and aging subscale parts formed in the unaged T31 condition.

  11. Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bergsma, S C; Kassner, M E; Li, X; Rosen, R S

    2000-08-08

    The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.

  12. Texture evolution of continuous cast and direct chill cast AA 3003 aluminum alloys during cold rolling

    International Nuclear Information System (INIS)

    The texture evolution of continuous cast (CC) and direct chill cast (DC) AA 3003 aluminum alloys during cold rolling was investigated by X-ray diffraction. The relationship between texture volume fractions and rolling true strain was described quantitatively by mathematical formulae. The effect of processing method (CC vs. DC) on texture evolution was determined

  13. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    Science.gov (United States)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  14. Fabrication of superhydrophobic surface with improved corrosion inhibition on 6061 aluminum alloy substrate

    Science.gov (United States)

    Li, Xuewu; Zhang, Qiaoxin; Guo, Zheng; Shi, Tian; Yu, Jingui; Tang, Mingkai; Huang, Xingjiu

    2015-07-01

    This work has developed a simple and low-cost method to render 6061 aluminum alloy surface superhydrophobicity and excellent corrosion inhibition. The superhydrophobic aluminum alloy surface has been fabricated by hydrochloric acid etching, potassium permanganate passivation and fluoroalkyl-silane modification. Meanwhile, the effect of the etching and passivation time on the wettability and corrosion inhibition of the fabricated surface has also been investigated. Results show that with the etching time of 6 min and passivation time of 180 min the fabricated micro/nano-scale terrace-like hierarchical structures accompanying with the nanoscale coral-like network bulge structures after being modified can result in superhydrophobicity with a water contact angle (CA) of 155.7°. Moreover, an extremely weak adhesive force to droplets as well as an outstanding self-cleaning behavior of the superhydrophobic surface has also been proved. Finally, corrosion inhibition in seawater of the as-prepared aluminum alloy surface is characterized by potentiodynamic polarization curves and electrochemical impedance spectroscopy. Evidently, the fabricated superhydrophobic surface attained an improved corrosion inhibition efficiency of 83.37% compared with the traditional two-step processing consisting of etching and modification, which will extend the further applications of aluminum alloy especially in marine engineering fields.

  15. THE INVESTIGATION ON THE RHEOLOGICAL BEHAVIOR OF SEMI-SOLID ALUMINUM ALLOY DURING DIE CASTING

    Institute of Scientific and Technical Information of China (English)

    X.J. Yang; J. Lin

    2002-01-01

    Under the condition of die casting and reheating temperature of 570-580° C, the Rhe-ological behavior of semi-solid aluminum alloy (A356) is pseudoplasticity at the shearrate of 2×10s-1×104 s-1, and also shows dilatancy at the rate over 106s-1.

  16. Strain hardening and damage in 6xxx series aluminum alloy friction stir welds

    DEFF Research Database (Denmark)

    Simar, Aude; Nielsen, Kim Lau; de Meester, Bruno; Pardoen, Thomas; Tvergaard, Viggo

    A friction stir weld in 6005A-T6 aluminum alloy has been prepared and analyzed by micro-hardness measurements, tensile testing and scanning electron microscopy (SEM). The locations of the various weld zones were determined by micro-hardness indentation measurements. The flow behavior of the vario...

  17. Influences on Burr Size During Face-Milling of Aluminum Alloys and Cast Iron

    OpenAIRE

    Shefelbine, Wendy; Dornfeld, David

    2004-01-01

    The Exit Order Sequence (EOS) theory discussed by previous LMA students predicts the size of burrs formed during face milling. Other influences are tool geometry, coolant use, and material properties in aluminum silicon alloys and cast iron. Used, worn tools also increase the size of the burr. The effect of speed and feed are also discussed, particularly with regards to cast iron.

  18. Industrial capability to chem-mill aluminum alloy 2219 in T-37 and T-87

    Science.gov (United States)

    Milewski, C., Jr.; Chen, K. C. S.

    1979-01-01

    Procedures and chemical baths were developed for chem-milling aluminum alloy 2219. Using a series of sample etchings, it was found that good etching results could be obtained by using 'white plastic for porcelain repair (toluol, xylol, and petroleum distillates)' on top of cellosolve acetate as resist coatings and ferric chloride as on etchant.

  19. Comparison of recrystallization texture in cold-rolled continuous cast AA5083 and 5182 aluminum alloys

    International Nuclear Information System (INIS)

    The recrystallization microstructure and texture of cold-rolled continuous cast AA 5083 and 5182 aluminum alloys with and without prior heat treatment were investigated by optical microscopy, X-ray diffraction and TEM. The results obtained were discussed with regard to the effect of Zener-particle pinning

  20. Comparison of recrystallization texture in cold-rolled continuous cast AA5083 and 5182 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [Department of Civil and Environmental Engineering, Beijing Jiaotong University (China); Liu, W.C. [Department of Chemical and Materials Engineering, University of Kentucky, 177 Anderson Hall, Lexington, KY 40506 (United States); Zhai, T. [Department of Chemical and Materials Engineering, University of Kentucky, 177 Anderson Hall, Lexington, KY 40506 (United States)]. E-mail: tzhai@engr.uky.edu; Kenik, E.A. [Metals and Ceramics Division, Oak Ridge National Laboratory, 100 Bethel Valley Road, Building 4515, MS-6064, P.O. Box 2008, Oak Ridge, TN 37831-6064 (United States)

    2005-02-15

    The recrystallization microstructure and texture of cold-rolled continuous cast AA 5083 and 5182 aluminum alloys with and without prior heat treatment were investigated by optical microscopy, X-ray diffraction and TEM. The results obtained were discussed with regard to the effect of Zener-particle pinning.