Effects of forging deformation on variant selection and morphology of α in TiB/near α-Ti composites

Abstract

The role of forging deformation on α-Ti in TiB/near α-Ti composites is still an unknown area. In the present work, the evolution of the variant selection and morphology of α-Ti was systematically investigated in as-sintered and as-forged TiB/near α-Ti composites through scanning electron microscope and electron back-scattering diffraction analysis. The results indicated that the α lamellae were refined, and their c-axes were either oriented at 45°or perpendicular to the Z-direction after hot forging. Six preferred orientation relationships (ORs) between TiB whiskers and α variants have been quantitatively identified using the misorientation axis-angle pair distribution maps. Compared to the as-sintered sample, the total length of the TiB/α phase boundary with six preferred ORs increased from 5.31% to 9.76% after hot forging. It was found that TiB contributed to the formation of the refined and equiaxed α variants that satisfied the preferred ORs with it. Moreover, an analysis of the reconstructed parent β grains revealed that the α variants heterogeneously nucleated from TiB, which did not satisfy the Burgers orientation relationship (BOR) with the parent β grains.