Michael Sean Zedalis

Effect of strain rate on tensile ductility for a series of dispersion-strengthened aluminum-based alloys

Abstract Rapid solidification processing, in the manufacture of elevated temperature aluminum alloys, results in significant supersaturation of solute elements in the aluminum matrix solid solution. These levels are shown to alter significantly the deformation characteristics of this class of alloys through the phenomenon of dynamic strain aging (DSA). That is DSA reduces tensile ductility at intermediate temperatures. The temperature ranges are found to be dependent on the solute element in solid solution and the strain rate of testing.

High-temperature discontinuously reinforced aluminum

High-temperature discontinuously reinforced aluminum (HTDRA) composites have been developed for elevated-temperature applications by incorporating SiC particulate reinforcement into a rapidly solidified, high-temperature Al-Fe-V-Si (alloy 8009) matrix. HTDRA combines the superior elevated-temperature strength, stability and corrosion resistance of the 8009 matrix with the excellent specific stiffness and abrasion resistance of the discontinuous SiC particulate reinforcement. On a specific stiffness basis, HTDRA is competitive with Ti-6-Al-4V and 17-4 PH stainless steel to temperatures approaching 480°C. Potential aerospace applications being considered for HTDRA include aircraft wing skins, missile bodies, and miscellaneous engine, spacecraft and hypersonic vehicle components.

On the nature of icosahedral phases in Al(Fe,V,Si) alloys

Abstract Icosahedral phases have been produced in a variety of Al(Fe,V,Si) alloy ribbons by planar flow casting of melts with constituent elements of high purity. Differential scanning calorimetry, X-ray diffraction and transmission electron microscopy have been used to probe these phases in detail. It is found in the binary AlFe and AlV alloys that the icosahedral edge length a is independent of composition over a wide composition range; a is about 0.508 nm and 0.526 nm in AlFe and AlV, respectively. The value for a in ternary AlFeV alloys is intermediate between these two values, and is seen to be a function of the alloy chemistry. This dependence is ascribed to a solid solution type effect wherein the Fe: V ratio in the icosahedral phases varies continuously. The addition of silicon to the ternary alloys has a minimal effect on a , but a pronounced effect in terms of reduction of stability of the icosahedral phase. The icosahedral phase transformation temperature is seen to be reduced by approximately 25 K per at.% Si.