Effect of combination variation of particle and matrix on the damage evolution and mechanical properties of particle reinforced metal matrix composites

In this article, SiCp/Al composites with matrices of different strengths reinforced by three sizes particles were manufactured by powder metallurgy process. The yield strength and ultimate strength of these composites ranged from 95 MPa to 379 MPa and 131 MPa–561 MPa respectively. In particular, in addition to the expected strengthening behavior, a weakening of the composite's yield strength and ultimate strength was found. This abnormal phenomenon was correlated with the effects of the combination variation of the particle and matrix. To study the mechanisms driving these effects, images and statistical data describing the evolution of the whole damage process were analyzed through in situ tensile testing. Two major types of damage, particle cracking and matrix slippage, were identified by the particle cracking rate fc and the slip band density ρs. Based on the growth characteristics of these two major damage types, three stages of damage evolution were defined, and the effect of these stages on the strengthening limit of the composites' mechanical properties was discussed. Furthermore, through the analysis of the microstructures and fracture morphologies of the composites, a damage factor Q was defined to describe the different failure mechanism and the strengthening limits of the composites. This work provides a better understanding of the relation between the composite components and the mechanical properties.