Microstructural evolution and mechanical characterisation of cold spray additively manufactured copper: a story of heat treatment

Cold Spray Additive Manufacturing (CSAM) is notable due to its ability to deposit materials with minimal heat input, offering technical advantages when compared to the majority of other metal AM processes employed, such as the high throughput deposition of challenging metals with low weldability. Recent advancements in 3D printing software’s and control systems coupled with readily sourced gases such as compressed air, have increased CSAM’s appeal across industries for cost-effective repair and fabrication of end-use parts deployable directly in field operations.

CSAM has already demonstrated its capability to produce dense complex near-net shape parts, however, several challenges remain during their fabrication. Resulting parts often exhibit low ductility, high residual stresses, and dimensional inaccuracies. This study investigates the effect of powder feed rate on the mechanical integrity and dimensional accuracy of pure copper parts produced via CSAM. The effect of heat treatment was also investigated through microhardness and in-situ uni-axial tensile testing to identify improvements in the bulk mechanical properties obtained such as ductility and strength. Characterisation of microstructural evolution utilising SEM and XRD is also carried out to evaluate the development of such improvements.