Microstructural characteristic and mechanical properties of titanium-copper alloys in-situ fabricated by selective laser melting

Abstract

In this paper, Ti-Cu alloys were in-situ fabricated by selective laser melting (SLM) with 1.25, 2.5 and 5 wt% Cu contents, namely Ti-1.25Cu, Ti-2.5Cu and Ti-5Cu, respectively. The microstructural characteristic and mechanical properties of Ti-Cu alloys were systematically investigated. The results showed that the SLM-fabricated Ti-Cu alloys have a fine microstructure, and the morphology of martensite exhibited a transition from parallel-sided plates or laths to acicular plates with increasing Cu content. Due to the accommodation effect of the martensitic transformation strain, the 14–20% of the martensite partitioning interfaces was constituted of {101̅1} twin boundaries. The microhardness, yield strength and ultimate tensile strength were enhanced synergistically with increasing Cu content, which can be attributed to the combined effects of grain-boundary strengthening, solid-solution strengthening, dislocation strengthening and precipitation strengthening.