Tensile Properties and Creep Behavior of Compositional Modified Orthorhombic Ti_2AlNb Alloys

摘要

Several beta stabilizing elements such as Mo, Cr, W, V and Fe have been added to Ti-22Al-27Nb alloy for substituting a portion of Nb in order to further improve the tensile properties and creep resistances of orthorhombic Ti2AlNb-based alloys. Six compositional modified alloys Ti-22Al-19.2Nb-2Cr, Ti-22Al-12.5Nb-2W-2Cr, Ti-22Al-10.8Nb-2Mo-2Cr, Ti-22Al-16Nb-2Cr-2V, Ti-22Al-11Nb-2Mo-1Fe, Ti-22Al-16.3Nb-2V-1Fe were prepared by plasma arc melting. The phase constitutions of these alloys were found to be B2+O or B2+O+α_2 phases. The tensile properties were investigated at room temperature, and the creep behaviors were investigated under 650℃/310MPa and 650 to 750℃/200MPa. The results showed that Mo+Fe and W+Cr addition improved effectively the 0.2% yield strength and creep resistance. Ti-22A1-11Nb-2Mo-1Fe alloy exhibited the lower transient creep strain and steady-state creep rate, and longer 1 % creep-strain lifetime than Ti-22Al-27Nb alloy at 650 to 700℃ creep. The dislocation-controlled creep deformation mechanism was suggested to the creep behaviors of the Mo+Fe-modified alloy.