Effects of thermal shock on mechanical properties and microstructural integrity of aluminum–SiC composites

Aluminum–SiC (Al–SiC) composites have gained significant prominence in the aerospace and automotive industries due to their exceptional combination of high strength-to-weight ratio, superior thermal conductivity, and excellent wear resistance characteristics. Despite
their widespread industrial applications, the behavior of these composites under cyclical thermal conditions remains inadequately characterized and understood. This comprehensive study meticulously examines the effects of cyclic thermal shock (consisting of 20 complete cycles
from 300 to 25 ○C) on the mechanical properties and microstructural integrity of Al–SiC composites containing 15 vol. % SiC reinforcement. Extensive mechanical testing revealed notable property degradation patterns: ultimate tensile strength decreased by 7.8% (from 320 to
295 MPa), yield strength diminished by 8.0% (from 250 to 230 MPa), and Vickers hardness reduced by 12.5% (from 145 HV to 130 HV).
More significantly, energy absorption properties exhibited pronounced deterioration, with impact toughness dropping by 33.3% and fracture
toughness declining by 28.0%, indicating a substantial compromise in damage tolerance capabilities. Detailed SEM microstructural analysis
identified three primary degradation mechanisms: matrix microcracking, SiC particle fragmentation, and interfacial debonding between the
aluminum matrix and SiC reinforcement. These findings emphasize the critical need for enhanced interfacial bonding strength and innovative
reinforcement strategies to improve thermal shock resistance in Al–SiC composites, particularly for applications involving thermal cycling
conditions.