DEFORMATION AND FRACTURE OF METASTABLE BETA TITANIUM ALLOYS (Ti-15Mo-5Zr AND Ti-15Mo-5Zr-3Al).

Abstract

Although mechanical twinning is suppressed by initial aging, considerable ductility is attained in Ti-15Mo-5Zr hardened by aging at 573 K for 1. 2 ks. Reduction in macroscopic ductility on further aging is related to inhomogeneous slip. Embrittled Ti-15Mo-5Zr exhibits a ductile, dimple type fracture surface. On the other hand, mechanical twinning is not induced in as-quenched Ti-15Mo-5Zr-3Al. The alloy is embrittled by precipitation of alpha -phase on aging at 623 K and shows a mixture of intergranular and dimple type fracture surface. Ductility of metastable beta -Ti alloys is discussed.