Effect of sintering temperature on microstructural evolution and mechanical properties of (NiCoCr)p/6061Al composites

Spark plasma sintering (SPS) was employed to fabricate (NiCoCr)p/6061Al composites at sintering temperatures ranging from 560 to 590 °C. The effects of sintering temperature on microstructural evolution, interfacial characteristics, and mechanical properties were systematically investigated. A multi-level heterogeneous structure was identified at the interface, wherein the central nanocrystalline zone comprised alternating Cr-rich and Co-rich nano-grains domains whose SAED patterns were provisionally consistent with B2-type and Al 9 Co 2 -type structures, respectively, while an amorphous structure is present at the interfacial periphery.The overall interface adopts a core–shell structure that fully encapsulates the NiCoCr reinforcing particles. This heterogeneous interfacial structure is inferred to act as a rigid load-bearing skeleton bridging the soft Al matrix and the moderately hard NiCoCr core, which may contribute to constraining matrix deformation and facilitating stress redistribution through the interfacial region. With increasing sintering temperature, the thickness of the core–shell structure progressively increases; however, at 590°C, excessive interfacial growth and partial consumption of the NiCoCr reinforcement are inferred to cause the proposed rigid skeleton to fragment into discretely dispersed isolated islands, thereby reducing the compressive strength of the composite to 359 MPa. The optimal sintering temperature is 580 °C, and the compressive strength is 547 MPa