In situ deformation behavior of TC21 titanium alloy with different α morphologies (equiaxed/lamellar)

Abstract

Abstract To study the effect of α phase morphology (equiaxed α (α E )/lamellar α (α L )) on the in situ tensile behavior of TC21 alloy, the slip band, dislocation, crack initiation, and propagation were analyzed by scanning electron microscopy (SEM) with in situ tensile stage and transmission electron microscopy (TEM). The results show that the slip bands first concentrate in the α E phases and easily truncate at the α/β phase boundaries, whereas the slip bands move across the α lamellae in the α L phase. Microcracks are easily generated in α E or α/β phase boundaries with large plastic deformation. When the quantity of α L is more than α E , the crack tip is more easily deflected at α phases or α clusters with different orientations, making the main crack propagation path more zigzag. When the volume fraction ratio of α E to α L is ~ 3:4, i.e., the volume fraction of α E is close to that of α L , TC21 alloy exhibits better strength and slower crack propagation rate.