Microstructure and Tensile Properties of Cu-Ti Composites Deposited by Cold Spray Additive Manufacturing.

In this study, copper-titanium (Cu-Ti) composite coatings with 6 wt.% titanium content were fabricated via cold spray additive manufacturing (CSAM) using nitrogen as the propellant gas. The synergistic effects of propellant gas temperatures (600 °C, 700 °C, 800 °C) and post-heat treatment temperatures (350 °C, 380 °C, 400 °C) on the microstructure and tensile properties were systematically investigated. Tensile testing, microhardness characterization, and fractography analysis revealed that increasing the propellant gas temperature significantly enhanced the plastic deformation of copper particles, leading to simultaneous improvements in deposit density and interfacial bonding strength. The as-sprayed specimen prepared at 800 °C propellant gas temperature exhibited a tensile strength of 338 MPa, representing a 69% increase over the 600 °C specimen. Post-heat treatment effectively eliminated the work-hardening effects induced by cold spraying, with the 400 °C treated material achieving an elongation of 15% while maintaining tensile strength above 270 MPa. Microstructural analysis demonstrated that high propellant gas temperatures (800 °C) promoted the formation of dense lamellar stacking structures in copper particles, which, combined with a recrystallized fine-grained microstructure induced by 400 °C heat treatment, enabled synergistic optimization of strength and ductility. This work provides critical experimental insights for process optimization in CSAM-fabricated Cu-Ti composites.