High-temperature mechanical behavior of B2-ordered Ti–Mo–Al alloys

Compressive stress–strain responses of stoichiometric and off-stoichiometric B2-ordered Ti–Mo–Al alloys over the temperature range 973–1373 K were examined to investigate the effects of composition and temperature on the mechanical behavior. The Ti–Mo–Al alloys exhibited impressive yield strengths at elevated temperatures, e.g., 818 MPa for Ti₅₀Mo₃₅Al₁₅ at 1073 K and 490 MPa for Ti₅₀Mo₂₅Al₂₅ at 1273 K. Positive temperature dependence of yield strength was observed in Ti₅₀Mo₂₅Al₂₅ below 1273 K but it had not been seen in either Ti₆₀Mo₂₅Al₁₅ or Ti₅₀Mo₃₅Al₁₅ throughout the test temperatures. Dislocation analyses of the compressed specimens indicated that the Ti–Mo–Al alloys primarily deformed via <111>slip. The mechanisms responsible for the variations of mechanical properties with composition and temperature are discussed by correlating with the antisite defects.