Compressive Mechanical Properties of Gradient Structured CrCoNi Medium-Entropy Alloy under High-Temperature and High-Strain-Rate Coupling
摘要
CrCoNi medium-entropy alloys (MEA) exhibit excellent mechanical properties under low-temperature conditions, while these properties decrease at room temperature and high-temperature conditions. The mechanical properties under high-temperature and high-strain-rate coupling conditions have always been a key issue in the research of CrCoNi MEA as a structural material. On the basis of surface sliding friction plastic deformation of CrCoNi MEA to construct gradient structures, this study conducted dynamic compressive mechanical properties tests at room temperature, 100, 200, and 300 °C on homogeneous and gradient CrCoNi MEA, with strain rates controlled within the range of 2500-7000 s−1. The experimental results show that the gradient structure significantly improves the yield strength of CrCoNi MEA at various temperatures and strain rates, with almost no plastic loss. In addition, both homogeneous and gradient CrCoNi MEAs exhibit positive strain rate sensitivity, and strain rate sensitivity increases with increasing temperature. The higher the strain rate, the stronger the strain hardening performance of CrCoNi MEA, which is crucial for it to exhibit high strain rate.