Influences Of Different Heat Treatment Methods On Mechanical Properties Of SiC/AZ81 Magnesium Matrix Composites

AZ81 magnesium alloy was chosen as the matrix alloy, 10μm SiC particulates with different content was used as the reinforcement, 7.5wt%SiC/AZ81 and 10wt%SiC/AZ81 were fabricated by melt-stirring method, then carrying different heat treatments on the composites, the effects of different heat treatments on microstructure,compression strength and wear resistance were investigated by microstructure observed,compression strength analysis and wear performance tested, while its strengthening mechanism was discussed. At last, the microstructure and mechanical properties of magnesium matrix composites after rolling were researched.Experimental results show that: the distribution and morphology of SiC particulate reinforcements are not changed, only accompanyβ-Mg₁₇Al₁₂ phase melting and precipitating after different heat treatments; and the wear resistance of SiC/AZ81 magnesium matrix composites is increased to some extent, because of the improved composition and distribution of second phase in the matrix can steady SiC particles, the solution treatment is the best method, especially the 7.5wt%SiC/AZ81, compared with the as-cast 7.5wt%gSiC/AZ81 magnesium matrix composites, the wear resistance increase by 51.8%. Both aging treatment and solution + aging treatment can enhance compression properties of SiC/AZ81 magnesium matrix composites, because of the second phaseβ-Mg₁₇Al₁₂ can hinder the dislocation slipping, leading to the matrix strengthening, after aging (20h) treatment,β-Mg₁₇Al₁₂ quantity is the most and the reticular incrustation is compaction, the compression strength of 10wt%SiC/AZ81 reach to 245.1MPa. With the rolling of SiC/AZ81 magnesium matrix composites, rolling streamlines are formed gradually, the average grain size decreases, the pattern of SiC particles has a tendency to passivating and rounding, strip and sharp SiC particles decrease, and the rolling processing leads to the refinement of SiC particles. The mechanical properties of SiC/AZ81 are improved greatly compared with the as-cast SiCp/AZ81 magnesium matrix composites, the tensile strength of 7.5wt%SiC/AZ81 is 235.1MPa, increase by 51.8%. The main reason for the enhancement in the wear resistance and compression properties is that heat treatment will change the distribution and morphology ofβ-Mg₁₇Al₁₂ phase.