Effects of heat-treatment on microstructures and mechanical properties of WO₃ particle and Al₁₈B₄O₃₃ whisker hybrid reinforced Al matrix composites by squeeze casting

In this paper, WO₃p and Al₁₈B₄O₃₃w hybrid reinforced aluminum matrix composites were fabricated by squeeze casting. Heat-treatment of the composites was carried out at 500 °C for different times. Gibbs free energy calculation indicated that the reaction of WO₃ with Al was spontaneous. DTA result showed that the reaction of WO₃ with Al took place at 396 °C and 487 °C. XRD results showed that the interfacial reaction occurred after heat-treatment at 500 °C for 5 h and 10 h and the reaction products were WO_2.90 and WO_2.83, which resulted in the formation of micro-voids at the interface between particle and matrix and led to mechanical properties of the composites decreasing. However, mechanical properties of the composites heat-treated for 10 h did not decrease obviously compared with that of heat-treated for 5 h. The reason may be that the produced aluminum oxide film covered the WO₃p and retarded progress of the chemical reaction.