Design of Ti−7Al−2V alloy with high specific strength by using cluster formula

Abstract

A near-α Ti−7Al−2V alloy was designed using cluster formula approach and prepared by laser additive manufacturing, whose specific strength is better than that of Ti−6Al−4V alloy. Its composition formula α-{[Al−Ti12](AlTi2)}15+β-{[Al−Ti14](V3)}2 features an enhancedα-Ti by increasing α unit proportion of 15/17 (with respect to 12/17 of Ti−6Al−4V alloy) and stabilized β-Ti via V alloying. This alloy possesses a good laseradditivemanufacturing processibility. At the as-deposited state, the microstructures are composed of fine basket-weave regions, coarse basket-weave regions and ultrafine αWidmanstättenlath regions. The surface roughness of coarse basket-weave regions is much smaller than that of fine basket-weave regions and ultrafine αWidmanstättenlath regions. The α-phase distribution in fine basket-weave regions is more uniform than that in the coarse basket-weave regions. Its ultimate tensile strength of 971−1005 MPa, yield strengthof 891−921 MPa andelongation of 4.5%−6.6% are close to those of Ti−6Al−4V alloy, and particularly, its specific strength of 224−232 kN·m/kg is better than that of Ti−6Al−4V alloy.