Mechanical, Microstructural and Wear Studies of a Ceramic Hybrid Reinforced ZE41 Magnesium Metal Matrix Composite Through Stir Casting Route

Abstract

In this investigation, ZE41 magnesium alloys reinforced with 2% weight of SiC and B₄C were manufactured through stir casting route under an inert environment. The microstructure of the unreinforced alloy, exhibits α Mg grains with uniformly distributed β Mg₇Zn₃ intermetallic phases at the grain boundaries. The addition of ceramic reinforcements decreased the average grain size and also formulated thin β Mg₇Zn₃ phases compared to the denser ones observed in the pure base matrix. The results of this work demonstrated that the tensile strength of the composites improved due to particle strengthening, grain refinement and presence of dislocations at the intermetallic regions and the best results were obtained for the hybrid ZE41 matrix (ZE41 + 2% SiC + 2% B₄C). The tensile strengthening mechanisms of the composites are discussed and the expected theoretical values of yield strengths are calculated for comparison. Additionally, the specimens' elastic moduli were evaluated experimentally and theoretically (using the Tsai Halpin model), with the results showing good agreement, particularly for the hybrid composite. The morphologies of the fractured specimens were also analysed and it has been observed that the hybrid composite exhibited a ductile mode of fracture due to the presence of uniform dimples. The impact strength and hardness values of all the composites was also found experimentally and the best results were obtained for SiC and B₄C composites which played a vital role in the selection of reinforcement particles for developing the hybrid composites. The wear analysis of the composites and their surface morphologies displayed considerable increase in friction coefficient and specific wear rate for hybrid composites at low and high loads.

Graphical Abstract