Effects of Zr addition on the phase stability of L1(2)-based Al-Ti-Cr alloys

Abstract

Zr was added to the Al-21Ti-23Cr (L1(2)+Cr2Al) alloy to improve the L1(2) phase stability at temperatures around 800 degrees C. It was found that the addition of Zr effectively reduced and delayed the decomposition of the L1(2) matrix into L1(2) and Ti(Cr,Al)(2) phases in the Al-21Ti-23Cr alloy. Furthermore, the temperature range of the L1(2) matrix decomposition was narrowed when Zr was added to. the Al-21Ti-23Cr alloy. It is suggested that improvement of L1(2) phase stability by the addition of Zr could be the result of two factors. First, the movement of the L1(2) single-phase field could be reduced by the addition of Zr, possible decreasing the fraction of L1(2) matrix decomposition. Second, atomic diffusion could be suppressed by the addition of Zr, possible delaying the precipitation of the Ti(Cr,Al)(2) phase in the L1(2) matrix. (C) 2005 Elsevier B.V. All rights reserved.