Microstructures and Mechanical Properties of a NiCoV Medium-entropy Alloy Processed by Spark Plasma Sintering
Author of the article: LUShenghan1, CHEN Songyang1, CAI Weijin1, LONG Qiang1, LAI Minjie2, XIONG Zhiping3, WANGZhangwei1, SONG Min1
Author's Workplace:1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China; 3. National Key Laboratory of Science and Technology on Materials under Shock and Impact, Beijing Institute of Technology, Beijing 100081, China
Key Words:medium-entropy alloy; spark plasma sintering; process optimization; mechanical property
Abstract:
The NiCoV face-centered cubic (FCC) single-phase medium-entropy alloy exhibits outstanding strength and
ductility, making it a highly promising structural material. In this study, a NiCoV alloy was prepared using spark plasma
sintering (SPS) technology, which is renowned for its rapid heating, low sintering temperature, and high product density,
making it particularly suitable for the rapid fabrication of high-performance alloys with fine grains. By ball-milling the
powder, porosity defects are eliminated in the alloy preparation process. During subsequent hot rolling, the hard phases
distributed along the grain boundaries in the alloy are redistributed, forming a composite microstructure with abundant
dislocation substructures, nanotwins, and uniformly distributed hard phases. This structure is distinct from the uniform FCC
single-phase structure of NiCoV alloys produced by traditional casting methods. The composite microstructure generated by
the SPS process combined with hot rolling, through the synergistic strengthening effect of dislocations, precipitates,
nanotwins, and grain boundaries, results in achieving a yield strength of 1 360 MPa and a tensile strength of 1 593
MPa, while maintaining a uniform elongation rate of 18.7%, thus realizing excellent strength-ductility matching. This study
not only optimizes the microstructure and mechanical properties of NiCoV alloys but also provides a new approach for the
preparation of high-performance medium-entropy alloys.