Structure of TiB precipitates in laser deposited in situ, Ti-6Al-4V–TiB composites

Ti-6Al-4V–TiB composites have been deposited in situ from powder feedstocks consisting of a blend of pre-alloyed Ti-6Al-4V and elemental boron using the laser engineered net-shaping (LENS™) process. The microstructure of the as-deposited composites has been characterized in detail using transmission electron microscopy (TEM) and high resolution TEM (HRTEM). A homogeneous refined dispersion of TiB precipitates is formed within the Ti-6Al-4V α/β matrix. These TiB precipitates exhibit the B27 orthorhombic structure that has been investigated in detail using HRTEM. A high density of faulting was found in most of the TiB precipitates and such faulting resulted in the formation of local layers exhibiting the Bf structure within the B27 TiB precipitates. The structure of the α-Ti/TiB interface has also been investigated using HRTEM.