In-situ study of dislocation coordinated plastic deformation mechanism in as-cast Ni33Co40Mn27 medium entropy alloy

Q Gao and B Sang and WB Wang and Q Wang and JQ Ren and XF Lu and JS Qiao, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 924, 147818 (2025).

DOI: 10.1016/j.msea.2025.147818

High-density dislocations and the simultaneous activation of multiple slip systems play a significant role in the deformation process of medium-entropy alloys (MEA). The in-situ scanning electron microscope/electron backscatter diffraction (SEM/EBSD) dynamic study of dislocation slip behavior and its interaction with grain boundaries is helpful in understanding the microdeformation mechanism of the alloy. In this work, the as-cast Ni33Co40Mn27 MEA alloy exhibits a tensile strength of 420 MPa and a fracture elongation of 45 %. The fracture mode is ductile, and its mechanical properties are better than traditional as-cast alloys. However, the geometric incompatibility of the as-cast alloy's local grain size heterostructure region leads to significant stress concentration which becomes the primary site for crack nucleation. The primary reason for the alloy's excellent mechanical properties is the simultaneous activation of multiple slip systems and the formation of high-density dislocations. This process promotes the formation of sub-grain boundaries, slows down stress concentration, delays the formation of microcracks, and significantly enhances the alloy's plastic deformation capability. The coordinated deformation mechanism in the alloy primarily includes grain orientation rotation and slip transfer. Through in-situ research, the deformation mechanism is deeply understood, providing a key experimental basis and theoretical guidance for the subsequent optimization of microstructure and improvement of the mechanical properties of MEAs and aiding in the design of higher-performance materials to meet the demands of extremely complex working conditions.

Return to Publications page