Effect of Vanadium Layer on Microstructure and Properties of TC4 (Ti-6Al-4V)/TiAl (Ti-48Al-2Cr-2Nb) Dissimilar Metals Produced by Laser Additive Manufacturing

Dissimilar metal samples of TC4/TiAl were successfully prepared by laser additive manufacturing (LAM) technology, with pure vanadium as the interlayer. The microstructure, phase composition, element distribution and mechanical properties at the interface of TC4/V and TiAl/V were analyzed by optical microscope (OM), scanning electron microscope (SEM) and backscattering diffraction (EBSD). The experimental results showed that the interface microstructure of TiAl/V is mainly composed of & gamma;, & alpha;2 phase and V solid solution. The microstructure of the TC4/V interface is mainly composed of & beta;-Ti and V solid solution. There are no holes, metallurgical defects or microcracks at the above two interfaces, and the interface is bonded well. With the increase in the number of deposition layers, the interface bonding depth increases, and its thickness increases from 30 & mu;m to 80 & mu;m. The mechanical properties tests showed that the tensile strength and elongation of dissimilar metals with two layers of V interlayer TC4/TiAl are the highest, and their values are 483 MPa and 0.35%, respectively. Compared with the one-layer V intermediate layer sample (tensile strength 405 MPa, elongation 0.24%), the tensile strength and elongation are increased by 19.2% and 45%, respectively. The tensile strength and elongation of dissimilar metals in three-layer V interlayer TC4/TiAl are the lowest, and their values are 350 MPa and 0.16%.