Wear and mechanical performance improvement in AZ31 Mg alloy reinforced with MoS2 and cBN through multi-pass friction stir processing
摘要
The novel AZ31/MoS₂ + cBN hybrid surface composites were synthesized through multi-pass FSP. A detailed investigation was conducted on the microstructural characteristics, mechanical behavior and wear performance of the developed composites. The attained data indicated that the three FSP pass led to the formation of a significantly refined and homogeneous scattering of reinforcement and minimal agglomeration. This improvement was primarily attributed to the sustained mechanical stirring and enhanced flowability of material after successive passes. Notably, the three-pass process resulted in substantial increases in both hardness (from 75 to 133 HV) and shear strength (from 136 to 206 MPa), respectively, accompanied by a transition to predominantly ductile fracture behavior, as evidenced by the fracture surface observations. When comparing the one-pass to the three-pass FSP, there was a remarkable diminishment in average grain size (from 10.89 to 5.97 µm), specific wear rate (from 0.51 to 0.26 mg/m) and coefficient of friction (from 0.42 to 0.29) highlighting the effectiveness of multi-pass FSP in enhancing the composite performance.