Enhanced Strength and Ductility of 3D-Printed Low-Pressure Cold Spray Copper Alloys through Strategic Heterogeneous Laminate Microstructure Design

Achieving an ideal balance of strength and ductility in 3D-printed low-pressure cold spray materials is highly desirable yet remains a significant challenge. This paper introduces a dual heterogeneous laminated Cu/CuCrZr composite structure, characterized by varying hardness ratios between the soft and hard domains, produced through low-pressure cold spray followed by post heat-treatment. The tailored heterogeneous Cu/CuCrZr microstructure features alternating coarse and fine grains, creating effective microstructural differences. These differences result in significant hetero-deformation-induced hardening, caused by the mechanical incompatibility between the soft Cu and hard Cu-Cr-Zr layers, leading to a remarkable combination of strength and ductility. This superior performance is largely attributed to the well-bonded particles and hetero-deformation-induced (HDI) strengthening during plastic deformation. The strengthening effect is due to the accumulation of a substantial number of geometrically necessary dislocations (GNDs) at the heterogeneous interface, which enhances work-hardening and simultaneously boosts both the strength and tensile ductility of the layered alloy. This innovative heterogeneous design strategy offers a promising solution to improve strength and ductility in low-pressure cold spray materials.

Keywords: Low-pressure cold spray, heterogeneous, laminate microstructure, hetero-deformation-induced strengthening