Ultrahigh strain hardening in a transformation-induced plasticity and twinning-induced plasticity titanium alloy

Abstract

In this study, a design strategy employing stress-induced β to hexagonal α′ martensitic transformation to develop a novel Ti-15Nb-5Zr-4Sn-1Fe alloy with ultrahigh strain hardening rate (~6.1 GPa) is reported. Microstructural investigations reveal that the superior strain hardening response is contributed by stress-induced β to α′ transformation with accompanying reversion of athermal ω and profuse internal {1¯011}<101¯2> and {112¯2}<112¯3> α′ mechanical twinning which promote twin-twin interactions, imparting high strength and outstanding uniform elongation. This study may serve as a template for developing new class of transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) Ti alloys based on β to α′ martensitic transformation.