Fei Huang

Designing heterogeneous grain structure (HGS) has been proven to be an effective strategy for overcoming the strength‐plasticity dilemma in copper and copper alloys. However, the construction of HGS in dispersion‐strengthened copper (DSC) for enhancing strength‐plasticity synergy remains challenging. Here, we proposed a novel method, multistep ball milling and reduction process followed by spark plasma sintering, to prepare DSC with an HGS to ameliorate the strength‐plasticity dilemma in DSC. Micron‐ and nano‐CuO and nano‐Y ₂ O ₃ powders were chosen as raw materials in this new method. The Cu‐7 vol% Y ₂ O ₃ composite, exhibiting a compressive yield strength of 438 MPa and a failure strain of 46.3%, exhibits a superior strength‐plasticity tradeoff in comparison with other DSC materials. Systematic experiments indicate that the back‐stress at the heterointerfaces between coarse grains and fine grains maybe not only raise the yield strength of Cu‐Y ₂ O ₃ composite, but also significantly enhance the strain hardening to increase the plasticity of the material. The new HGS designing route in this study offers a feasible pathway to develop DSC with a remarkable enhancement in strength and plasticity.