The role of twinning and nano-crystalline ? phase on the fatigue behavior of the metastable ß Ti-15Mo alloy

This work evaluated in depth the fatigue and fracture behavior of the metastable β Ti-15Mo alloy considering the presence of deformation twins and athermal nano-crystalline ω phase in the microstructure. Regardless of the microstructural condition studied, the as-received and the solution treated and quenched materials, ω phase remained unchanged, guaranteeing the static mechanical properties at acceptable levels. The mechanism of fatigue fracture was related to the existence of twins and maximum shear stress planes near the direction of screw dislocation motion in the BCC structure. The significant amount of deformation twins in the initial microstructure did not alter the fatigue limit, because the solution treated and quenched material unexpectedly developed twins during the fatigue test.