Effect of sintering temperature on microstructure and properties of SiCp/6061Al composites
摘要
In this study, SiCp/6061Al composites were fabricated using hot isostatic pressing (HIP) sintering, and the effects of sintering temperature on the phase composition, microstructure, mechanical properties, corrosion resistance, and thermal properties of the composites were systematically investigated using XRD, SEM, a universal testing machine, and an electrochemical workstation. The results showed that the composites mainly consisted of Al, Si, SiC, Al4C3, and Mg2Si phases under different sintering temperatures, and the content of the brittle Al4C3 phase increased with rising temperature. Meanwhile, higher sintering temperatures led to more uniform dispersion of SiC particles and improved densification of the composites.Mechanical tests revealed that the tensile strength and microhardness of the composites first increased and then decreased with temperature, reaching maximum values of 288.7 MPa and 85.4 HV at 550 °C, respectively. In contrast, the elongation, flexural strength, and impact toughness peaked at 500 °C, with values of 11.6%, 591.6 MPa, and 18.37 J/cm2, respectively. Fractographic analysis further indicated the presence of fine dimples and core–shell structures formed by SiC particles and Al4C3 phases, suggesting good fracture toughness of the composites.The composite sintered at 550 °C exhibited the lowest coefficient of thermal expansion (15.47 × 10−6 K−1) and the highest corrosion potential (− 1168 mV). Moreover, the thermal conductivity of the composite initially increased and then decreased with temperature, reaching a maximum of 187.7 W m−1 K−1 at 500 °C. Therefore, considering the overall mechanical and physical properties, 500 °C is identified as the optimal sintering temperature for fabricating SiCp/6061Al composites via hot isostatic pressing.