Phase Stability in the Al (6−x) Cu x Zr 2 System for 0 < × < 1.

We have determined the structures and thermal stability of A1(6-x) CuxZr2(0 ≤ x ≤ 1) powders prepared by mechanically alloying elemental powder mixtures. In the as mechanically alloyed condition the structure is L12 for all x. After heating to 750°C the alloy is single phase DO23 for 0 < x 0.2, is a two-phase mixture of DO23 and Ll2 for 0.2 < x < 0.6, and remains in the Ll2 phase for 0.6 < x < 1. Al5CuZr2 is stable in the Ll2 structure up to 1300°C. The lattice parameter of the annealed L12 phase is independent of x.