Defect healing and material response in As-Cast Al18B4O33w-SiCw/6061Al composite via current-assisted hot forming

Abstract

As cast whisker-reinforced Al matrix composites are prone to cracking in subsequent forming processes due to numerous micro defects and poor formability, which limits their application. This work investigates the healing effects of current-assisted rolling and upsetting on cracks and micropore defects in a 6061Al composite reinforced with a total of 20 vol% (SiCw and Al₁₈B₄O₃₃w), as well as the impact on the mechanical properties. The thermal compression behavior of the 20 vol% (SiCw + Al₁₈B₄O₃₃w)/6061Al composite was also analyzed systematically to investigate their thermal deformation characteristics. The results show that the combination of current with upsetting and rolling can improve interfacial adhesion between the matrix and the reinforcement phase, reduce internal micropores and microcracks, and increases the density of the composite to 1.009 and 1.053 times that of the die-cast state, respectively. The fracture mode partially transitions to ductile fracture, while the composite’s ultimate tensile strength increases by up to 101.63%. The formation of a high-temperature, high-pressure coupled field leads to crack closure is the main reason for defect healing in current-assisted forming processes. This work provides insights into solving the problem of poor formability of as cast whisker-reinforced Al matrix composites.