Effect of interlayers on thermal residual stresses in diamond/MPEA composites predicted by finite element method

The thermal residual stresses in diamond/MPEA (multi-principal element alloy) composites with various interlayers were analyzed using finite element method by both macro- and micro-models. Firstly, we investigated the temperature evolution in the composites during the cooling stage of the spark plasma sintering process. Then, the effects of interlayers introduced between the diamond and MPEA on the evolution and distribution of thermal residual stresses within the composites were studied. The simulation results demonstrate that incorporating a metal interlayer can effectively reduce thermal residual stress and elastic strain in the composites through plastic deformation, particularly when utilizing a metal interlayer with reduced yield strength. Comparatively, a carbide interlayer induces a high-level thermal residual stress primarily located in the carbide interlayer itself and the proximate contacting areas in diamond and the binder phase. Particularly, this stress will not decrease the mechanical properties of the composites, since it has a tensile first principal stress parallel to the interfaces formed between the carbide interlayer and metal interlayer, as well as the carbide interlayer and diamond, and a compressive third principal stress perpendicular to those interfaces. Consequently, the diamond composites with both a metal interlayer and a carbide interlayer are expected to exhibit lower levels of residual stress, which protect diamond particles from graphitization, thereby resulting in superior mechanical performance.