Enhancing strength-ductility synergy of thermally oxidized dual-phase HEA particles reinforced aluminum matrix composites via heterogeneous interface

Abstract

This work firstly oxidizes single-phase high entropy alloy (HEA) to form FCC and BCC dual-phase structure, and also introduces multi-component nano-oxides on surface to prepare oxidized HEA (OHEA) reinforcements, followed by preparation of OHEA/Al composites by spark plasma sintering. The introduction of O element accelerates interdiffusion between OHEA and Al matrix. FCC phase inside OHEA evolves into soft phase, and BCC matrix phase evolves into hard phase, forming heterogeneous interface in OHEA/Al composites. During tensile process, cracks preferentially initiated in hard phase due to severe stress concentration, and the soft phase effectively retarded crack propagation. Compared with 2024Al matrix, yield strength, tensile strength, and elongation of OHEA/Al composites increased by 35.31%, 57.34%, and 63.33%, respectively, realizing excellent combination of strength and toughness. Grain refinement, thermal mismatch, Orowan, and load transfer strengthenings synergistically improve the performance. The proposed method provides a promising avenue to optimize the properties of composites by pre-oxidizing HEA particles to construct heterogeneous interfacial structure.