Lenticular Twinning Within Α’ Martensite in Ti-6Al-4V at Early Deformation Stage

Twinning in α’ martensite in titanium alloys often occurs during rapid cooling or thermal cycling such as additive manufacturing process. This work reported α’ martensitic microstructure formed in Ti-6Al-4V alloy after room-temperature compression to ∼5% strain. Large-scale lenticular deformation twins were observed in martensite for the first time, which were evidently different in morphology and twinning system from nanotwins in quenched martensite. The emergence of such twins at only ∼5% strain resulted from variant selection and larger thickness of martensite and different stress state in martensite during deformation.