Microstructure control in two-phase Al-21Ti-23Cr alloy

Abstract

To improve the mechanical properties of the Al-21Ti-23Cr two-phase alloy consisting of L1(2) matrix and 20 vol% Cr2Al as a second phase, microstructure control was conducted through the aging treatment as a thermal process and the addition of V and Zr as conventional alloying. It was found that TiAlCr was precipitated as a third phase in the L1(2) matrix by the aging treatment at 800 and 1000 degrees C, and its size was smaller at 800 degrees C than at 1000 degrees C. The yield strength of the aged alloy increased rapidly only at 800 degrees C although the third phase was precipitated at both 800 and 1000 degrees C. In the V-added two-phase alloys, the yield strength and the strain increased simultaneously when V was added up to 3 at%, which is attributable to the improvement in the ductility of Cr2Al. Microstructure control conducted in this study suggests the possibility of improving the mechanical properties of Lit (Al,Cr)(3)Ti-based two-phase alloy by precipitating the fine third phase in the Lit matrix and enhancing the ductility of the second phase. (C) 2000 Elsevier Science Ltd. All rights reserved.