Twin-wire plasma arc additive manufacturing of the Ti–45Al titanium aluminide: Processing, microstructures and mechanical properties

Abstract

In recent years, the twin wire arc additive manufacturing technique has been proved feasible of fabricating titanium aluminides with low cost. To address the concerns on the low thermal efficiency induced by the previous gas tungsten arc welding-based process, in the present research the twin-wire plasma arc additive manufacturing system is developed using the compressed plasma arc power. Subsequently, the newly developed system is used to fabricate the binary Ti–45Al titanium aluminide to verify the feasibility. And the analysis on microstructure and mechanical properties is performed afterwards. Generally, the titanium aluminide with target composition and low texture level has been successfully fabricated using the compressed plasma arc system. Compared to other titanium aluminides fabricated using the previous system, the layer band microstructure is considerably weakened. However, the intergranular cracks in the as-fabricated deposition indicate that higher interpass temperature is certainly required for the new technique. The improvement of the microstructural homogeneity achieved by the new system provides valuable reference for weakening the microstructural and mechanical anisotropies in the wire arc additively manufactured titanium aluminides.