Hot deformation behaviors of Bi₂O₃-coated Al₁₈B₄O₃₃ whisker reinforced aluminum matrix composite with high formability

A pure aluminum matrix composite reinforced by Bi₂O₃ coated Al₁₈B₄O₃₃ whisker was fabricated by squeeze casting method. The hot extrusion and compression behaviors of composites with different Bi₂O₃ coating contents are investigated. The results show that the bismuth, the interfacial reaction product, existing at the interface as liquid state at elevated temperature results in the reduction of the steady-state extrusion load and maximum compressive flow stresses, and the decrease of the probability of whisker fracture during hot deformation process. Moreover, unlike many surface cracks can be seen in the extruded composite without whisker coating, the surface crack-free extruded rods can be obtained for composites with whisker coating. For the as-cast or extruded Bi₂O₃ coated Al₁₈B₄O₃₃ whisker-reinforced pure aluminum matrix composites, a suitable Bi₂O₃ coating content exists for the optimization of the ultimate tensile strength and elongation to fracture.