ECAP effects on microstructure and mechanical behavior of annealed WS2/AZ91 metal matrix composite

Abstract

Abstract Magnesium is the lightest metal and is extensive in the structural application. The metal matrix composites are developed to improve the strength of magnesium alloys. In this research, AZ91 alloy reinforced with 1 wt% WS2 was produced using stir casting process. The composite was homogenized for 24 h at 410 °C and subsequently aged for 10 h at 200 °C. The severe plastic deformation was performed using equal channel angular pressing (ECAP). The phase composition was analyzed using X-ray diffraction techniques. The microstructure, fractography, and mechanical properties of ECAPed composites have been investigated using scanning electron microscope, and universal testing machines, respectively. The results indicate that B-phases are present in the form of particles inside and at grain boundaries in annealed composites, which are refined to needle-shaped precipitates at grain boundaries, and grains size is refined to 0.2 μm after 4passes of ECAP. Microhardness and tensile yield strength are proportional to the number of passes, and 20.45% and 103.5% are increased respectively after 4pass. The UTS was found to be maximum (324.8 MPa) for 4P WS2/AZ91. Fractography analysis revealed that plastic fracture in annealed and elastic-plastic fracture occurred after 4P WS2/AZ91 MMC.