Synthesis of ternary L10 compounds of Ti–Al–Zr system and their mechanical properties

A number of ternary Ti–Al–Zr alloys with different compositions around the binary γ-TiAl (L10 structure) were prepared and annealed at 1273 K for 10 h followed by quenching. Almost single γ-phase is produced in a rather wide composition region of Al50(Ti50−x−yAlxZry) with 0 ≤ x ≤ 15 and 0 ≤ y ≤ 15. Both lattice parameters, a and c increase with increasing Zr concentration due to larger atomic radius of Zr than those of Al and Ti. The c/a ratio of Al50Ti50−xZrx decreases towards unity as x increases. The Vickers hardness value increases rapidly with increasing Zr substitution. Compression tests at high temperatures for Al50Ti50−xZrx and Al55Ti45−xZrx with x = 5, 10 or 15 showed that except for Al50Ti45Zr5, specimens underwent brittle fracture below 1000 K; only the Al50Ti45Zr5 specimens exhibited a considerable plastic strain at all the test temperatures, and the temperature dependence of the yield stress showed a peak at 973 K with the peak yield stress as high as 1000 MPa, indicating a possible application of this ternary alloy.