Effect of Alloy Addition on Structure and Properties of Cast Ti-7.5 percent Mo Alloy

摘要

The present work is a study of the effect of 1 wt percent addition of a series of allaying elements on the structure and properties of a Ti-7.5 percent Mo system. The results indicate that the phase/crystal structure, microstructure and mechanical properties of Ti-7.5 percent Mo alloy can be significantly changed by small amounts of alloy addition. Ti-7.5 percent Mo is a typical orthorhombic #alpha#" phase alloy. When 1 wt percent zirconia or niobium is added, its fine, acicular martensitic structure of #alpha#" phase remains, microhardness increases 25-29 percent, bending strength increases 13-21 percent, while modulus only slightly increases. When chromium is added, a significant amount of equiaxed, #beta# phase is retained, and microhardness, strength and modulus all largely increase. When iron is added, the equiaxed #beta# phase becomes the only dominant phase, and its hardness, strength and modulus all become the highest among all titanium alloys in this study. The cast Ti-7.5 percent Mo-l percent Nb and Ti-7.5 percent Mo-l percent Zr alloys exhibit higher strengths than do Ti-7.5 percent Mo, Ti-15 percent Mo, Ti-13 percent Nb-13 percent Zr, c.p. (commercially pure) Ti and Ti-6 percent Al-4 percent V, while maintaining their low moduli.