Enhanced strength and microstructural homogenization in material extrusion copper via HIP assisted by uniform rapid quenching

초록

This study presents a comprehensive investigation into the microstructural and mechanical evolution of copper fabricated by material extrusion (MEX) additive manufacturing and subsequently densified using hot isostatic pressing assisted by uniform rapid quenching (HIP with URQ). The URQ process enabled significant densification, increasing the apparent density from 8.42 to 8.46 g/cm3 and reducing porosity from 0.40% to 0.30%. Grain coarsening was effectively suppressed despite high-temperature exposure, and a uniform equiaxed grain structure with annealing twins was maintained throughout the build. HIP with URQ treated copper exhibited a remarkable improvement in mechanical performance, achieving a yield strength of 93.25 MPa and tensile strength of 217.92 MPa—representing 25% and 9% increases, respectively, over as-sintered copper. Unlike the as-sintered specimens, which showed strong height-dependent variability and stress serration, the HIP with URQ treated specimens demonstrated uniform mechanical properties and stable deformation across all layers. Fractographic and EBSD analyses confirmed the elimination of layer-related defects and heterogeneous high angle grain boundaries, leading to lower stress concentrations and more homogeneous deformation behavior. Overall, HIP with URQ serves as a highly effective post-processing strategy to produce high-strength copper with a uniform microstructure by eliminating porosity, suppressing abnormal grain growth, and enhancing interlayer bonding in MEX-processed parts. © 2026 Elsevier B.V.

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