Investigation of the relationship between microstructural evolution and mechanical properties in a metastable β-ZrTiAlV alloy

Abstract

In this study, the relationship between microstructural evolution and mechanical properties of a metastable β-ZrTiAlV alloy during compression was investigated. Microstructure characterization revealed that three different morphologies of α′ martensite, 101¯2 twinned α′ martensite, untwinned α′ martensite and α′ martensite paired were triggered at the initial deformation stage. With increasing deformation strain, these three kinds of α′ martensite undergo a process of widening and merging, and eventually form the 101¯2twin-related α′ domains, normal α′ domains and connected α′ domains, respectively. Mechanical properties test shows that the alloy exhibits a relatively high yield strength of 900 MPa and a high work hardening rate (about 6000 MPa) during compression. This high yield strength is attributed to the high triggering stress of deformation-induced β to α′ martensite transformation at initial deformation stage and the high solid solution strengthening effect of large amount Ti. The activation of α′ martensite and 101¯2 internal twins brings about the transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) effects, giving the alloy a substantial high work hardening rate, and their evolution with increasing strain leads to nonlinear evolution of the work hardening rate.