Shear strength at the interface between aluminum and ceramics in model composites fabricated by squeeze casting

The shear strength at the ceramic-aluminum alloy interface of composites fabricated by squeeze casting was measured. Ceramics used were SiC, Si3N4 and Al2O3, and pure aluminum, JIS AC8A and 2024 alloys were used as matrices. The shear strength was measured by pushing out a rectangular bar-like ceramic (cross-section: 5 mm x 10 mm) which were enveloped in an aluminum alloy by squeeze casting. The good bonding between ceramics and aluminum alloys was obtained by squeeze casting. Fracture of pure aluminum matrix composites occurred in the aluminum site near the interface. However, fracture occurred at the interface in the case of SiC-AC8A alloy composite and the shear strength is slightly lower than that of the pure aluminum. Fracture behavior of AC8A matrix composites is classified into three stages; initial linear stage, debonding and sliding. The shear strength was measured up to 573 K for each alloy, and decreased linearly with increasing temperature. The shear strength is much related to the roughness of the ceramic surface and increases with the increase in the roughness. The influence of heat treatment on the shear strength was also examined. The shear strength of SiC-pure aluminum did not change by heating for 16 h at 823 K, but that of SiC-2024 decreased.