Microstructure and mechanical properties of heat-treated cold spray additively manufactured titanium metal matrix composites

Abstract

Cold spray additive manufacturing (CSAM) can produce particle-reinforced metal matrix composites (MMCs) by accelerating metal/metal or metal/ceramic particle combinations towards a substrate surface. The harder reinforcement particles become embedded into the softer metallic matrix. The secondary material may also help reduce the deposit's porosity depending on the particles' relative hardness and density. In this research, four material combinations were investigated by adding one of the following secondary materials at 10 wt% to commercial-purity (CP - Grade 2) titanium powder; (i) yttria-stabilised zirconia - (Y2O3)0.08(ZrO2)0.92, (ii) titanium carbide – TiC, (iii) titanium diboride – TiB2, and (iv) tungsten – W. The mechanical properties of samples following vacuum heat treatment are compared and related to the microstructural interactions between the two materials during annealing. These results show that cold spraying a hard secondary material at 10 wt% with titanium has a reinforcing effect, increasing the material's tensile strength; however, its ductility decreases slightly. The strengthening and ductility loss effect was particularly notable for the Ti blends with W and TiC.