The influence of powder morphology on the microstructure and mechanical properties of as-sprayed and heat-treated cold-sprayed CP Ti

This article reports the impacts of the powders morphologies and post-processing heat treatment on microstructure and mechanical properties of cold-sprayed commercial pure (CP) Ti deposits. The results show that cold-sprayed CP Ti deposited from spherical-shape powder exhibit lower porosity and hardness than that produced from irregular-shape powder. According to LECO analysis, cold-sprayed CP Ti deposits made from irregular-shape powder had higher oxygen and nitrogen contents than those made from spherical-shape powder. The results indicated that irregular-shape powder was more reactive with oxygen and nitrogen than spherical-shape powder, owing to differences in particle velocity and surface area. Post-processing heat treatment in a high-vacuum furnace at 920, 990, and 1100 °C dissipates particle boundaries, removes sub-micron pores, and greatly enhances the tensile characteristics of cold-sprayed CP Ti deposits. After post-heat treatment, cold-sprayed CP Ti deposits made from spherical powder have a higher elongation to break and a slightly lower tensile strength than cold-sprayed CP Ti made from irregular-shape powder. Furthermore, SEM microstructure images reveal that grain size increases when the temperature of the post-heat treatment rises. On the other hand, cold-sprayed CP Ti manufactured with spherical-shape powders has a larger grain size than cold-sprayed cp-Ti made with irregular-shape powders.