Evolution of inhomogeneous reinforced structure in TiBw/Ti-6AL-4V composite prepared by pre-sintering and canned β extrusion

Abstract

2.5vol.% TiBw/Ti-6Al-4V composite with a discontinuous columnar reinforced structure was successfully fabricated by pre-sintering and subsequent canned β extrusion process. Detail investigation on microstructural evolution revealed that intermediate Ti3B4 rather than TiB was substantially synthesized on the surface of coarse Ti64 powders due to insufficient reaction during pre-sintering, but the growth of TiB whiskers particularly along c-axis was significantly accelerated by subsequent canned β extrusion, mainly resulting from the introduced high pressure and severe plastic deformation, while highly preferred orientation of TiB whiskers along extrusion direction was gradually developed. As a result, a discontinuous columnar reinforced structure in TiBw/Ti64 composite was achieved and led to superior mechanical properties of ~1450MPa in ultimate tensile strength and ~8.2% in fracture elongation at ambient temperature for the as-extruded composite.