Microstructure and mechanical properties of heterogeneous layered titanium alloy components fabricated via additive manufacturing

The additive manufacturing of heterogeneous layered titanium alloy is realized by the alternating deposition of TC4 and TA2 using a double wire plasma system. The components have good deposition morphology and mechanical properties. OM, SEM, backscattered electron diffraction technique (EBSD), XRD etc. were used to analyze the microstructure, mechanical properties were tested with microhardness and compression properties. The results show that TA2 and TC4 regions are mainly composed of lamellae α phase and α+β phase of basketweave and colonies structure. The grains in each region grow in the opposite direction of heat flow. The grain boundary characteristics and crystal orientation of TC4 region and TA2 region have similar laws, but due to the differences of phase growth of heterogeneous materials, the growth direction of β phase has changed between different layers, and the original β phase growth direction of TC4 region will grow along a preferred orientation of the deposited TA2 region, which limits the phenomenon of continuous growth of β phase into coarsened columnar crystal. In the layered structure, the hardness of TC4 region is significantly higher than that of TA2 region, and the hardness increases along the deposited direction. The component has close compressive strength along different directions, nearly 2.0 GPa, but the special layered structure formed alternately by TC4 and TA2 has high fracture strain (0.33) along the deposited direction and high yield strength (1 133 MPa) along the travel direction. © 2022 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.