Severe plastic deformation induced nano dispersion and strengthening effect in oxide dispersion strengthened copper fabricated by cold spray additive manufacturing

Abstract

This work presented a novel net-shape-forming technology to prepare oxide dispersion strengthened (ODS) copper by cold spray additive manufacturing. There were three types of Al2O3 particles in the internal oxidation Cu-Al2O3 raw powders. After cold spraying, two types of nano-sized Al2O3 inside the raw powder were inherited into the deposition, and the micro-sized Al2O3 on the powder surface was crushed to nano-size under severe plastic deformation, which dispersed along the interface of deformed powder due to the plastic flow of Cu caused by adiabatic shearing. The plastic deformation produced by cold spraying was 20% higher than the hot extrusion with extrusion ratio of 11:1, which fully achieves the Al2O3 fragmentation, dispersion distribution and densification of the cold sprayed deposition. Moreover, due to the significant work hardening and grain refinement effect by SPD during cold spraying, Vickers hardness and nanoindentation hardness of the ODS Cu deposition increased to 185.63 HV3 and 2.76 GPa, respectively, which were significantly higher than the raw powders and hot extrusion sample.