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 (TM)) 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 alpha/beta 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 B-f structure within the B27 TiB precipitates. The structure of the alpha-Ti/TiB interface has also been investigated using HRTEM. (c) 2005 Elsevier B.V. All rights reserved.