Interface structure and tensile behavior of high entropy alloy particles reinforced Al matrix composites by spark plasma sintering

Aluminum matrix composites (AMCs) reinforced with AlCoCrFeNi high entropy alloy (HEA) particles were fabricated by spark plasma sintering (SPS). The interface formation between the HEA particles and Al matrix, tensile properties and fracture behavior were investigated. The interface has a two-layer structure, the interface reaction layer close to the HEA particles was Al13(CoCrFeNi)4, and the interface reaction layer near the Al matrix was composed of Al9(CoFeNi)2 and Al18Cr2Mg3. The addition of HEA particles increased the yield strength, and reduced tensile strength and elongation of the composites. The fracture occurred at the interface reaction layer near the HEA particles, exhibiting obvious brittle fracture feature. The tensile fracture mechanism of the SPSed HEA/Al AMCs can be attributed to the poor plastic deformation ability of continuously distributed Al13(CoCrFeNi)4 and aggravated degree of stress concentration at interface reaction layer close to the HEA particles.