Demonstration of martensite reorientation-induced plasticity by ultra-high strength titanium alloys

In this study, Ti-4.5Al-2.5Fe-0.25Si and Ti-4.6Al-2.0Fe-0.25Si alloys demonstrating martensite reorientation-induced plasticity (MRIP) were investigated via ex-situ electron backscattering diffraction and field-emission transmission electron microscopy. The alloys were designed such that the annealed microstructure consisted of primary α, retained β, and athermal martensite with sheared nano-domains. The alloys exhibited deformation-induced reoriented martensite during deformation. Three reorientation sites of martensite, retained β, nano-domain, and sheared nano-domain, were observed inside the athermal martensite. These transformations resulted in grain refinement and martensite reorientation. This MRIP alloys exhibited an appreciable combination of strength (yield strength: 882 MPa and ultimate tensile strength: 1474 MPa) and ductility (23.7%).