Superb strength-ductility synergy in Si added metastable high-entropy alloys at cryogenic temperature via reinforced TRIP effect
(1. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350116, China;
2. College of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350118, China;
3. Fujian Provincial Key Laboratory of New Material Preparation and Forming Technology, Fuzhou 350118, China;
4. Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China;
5. School of Mechanical & Electrical Engineering, Putian University, Putian 351100, China)
2. College of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350118, China;
3. Fujian Provincial Key Laboratory of New Material Preparation and Forming Technology, Fuzhou 350118, China;
4. Beijing Key Laboratory of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China;
5. School of Mechanical & Electrical Engineering, Putian University, Putian 351100, China)
Abstract: The tensile behavior of (Fe50Mn30Co10Cr10)100-xSix (x=0 (Si0), 2 (Si2)) metastable HEAs prepared by selective laser melting was studied at cryogenic temperatures. The results demonstrate that the addition of Si leads to lattice distortion and a decrease in stacking fault energy, especially at 77 K, which significantly promotes transformation- induced plasticity (TRIP) in Si2 HEAs. The yield strength, tensile strength, and ductility of Si2 HEAs are 505.2 MPa, 1364.1 MPa, and 19%, which are 43%, 53% and 58% higher than those of Si0 alloy, respectively. TRIP is the main deformation mode, in addition to dislocation slip, and plays a key role in strengthening. The reinforced and continuously sustained TRIP maintains a dynamic strain distribution during deformation. Ultrahigh strain hardening greatly enhances the strength and ductility.
Key words: Fe50Mn30Co10Cr10 HEAs; selective laser melting; cryogenic temperature; Si addition; transformation- induced plasticity (TRIP) effect