Zr was added to the Al-21Ti-23Cr (L1 2 +Cr 2 Al) alloy to improve the L1 2 phase stability at temperatures around 800 °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.