Mechanical properties of the (Ti0.615Zr0.385)100–3.9x(Cu2.3Fe1.6)x alloys containing amorphous martensite

Abstract

Martensitic amorphization is a novel phenomenon of solid-state amorphization firstly reported in metastable β-Ti alloys. However, the mechanical properties of the β-Ti alloys containing intragranular amorphous martensite remain unexplored. In this work, the microstructures, compressive and tensile properties of the (Ti0.615Zr0.385)100–3.9x(Cu2.3Fe1.6)x alloys were investigated. It is found that martensitic amorphization exists in the as-cast Ti59.1Zr37Cu2.3Fe1.6 (x = 1) alloy. During compression, deformation-induced β-Ti to α″-Ti martensitic transformation takes place in the alloy with x = 1. With increasing x, the deformation-induced martensitic transformation of β→α″ is fully suppressed due to the increased phase stability. The Ti59.1Zr37Cu2.3Fe1.6 alloy with amorphous martensite exhibits the highest yield strength during compression, which is attributed to the strong blocking effect of the dislocation glide by the intragranular amorphous phase. However, the Ti59.1Zr37Cu2.3Fe1.6 alloy exhibits catastrophic failure without plasticity upon tension, which is associated with the brittle nature of the amorphous phase under tension as well as the severe stress concentration between the crystalline and amorphous phases. These results correlate the microstructures and mechanical properties of the Ti-based alloys with martensitic amorphization.