High entropy alloy reinforced aluminum matrix composites prepared by novel rotation friction extrusion process: Microstructure and mechanical properties

A novel rotation friction extrusion (RFE) process was taken to fabricate CrMnFeCoNi high entropy alloy (HEA) particles reinforced aluminum matrix composites (AMCs). The experimental methods and the first principle calculation based on density functional theory were employed to study the microstructure and mechanical properties of the composites. Results showed that the HEA particles reacted violently with the aluminum (Al) matrix during RFE. The average grain size of the AMCs was 3.6 mu m, which was significantly lower than that of the RFEed Al (13.2 mu m). Numerous second phases with FCC structure were formed, as a result of the large ther-modynamic driving force and the enhanced element interdiffusion. The tensile strength of the AMCs showed substantially enhanced compared to that of RFEed Al, which could be ascribed to load transfer, dislocation strengthening, fine-grained strengthening and Orowan strengthening. The uniform elongation of the AMCs was lower than that of the RFEed Al, which was explained by the fine grain size of the AMCs resulting in high dislocation dynamic recovery rate.