Mechanical Shearing-Aided One-Step Compound Casting of Al/Fe Bimetal

Mechanical shearing is used to prepare the Al/Fe composite with one-step compound casting. It usually requires two steps: hot dipping and casting. The mechanical shearing intensity and application time are varied to study the effect of the shearing on the microstructure and the interface bonding strength. The oxide layer on the surface of the steel inhibits metallurgical bonding on the Al/Fe interface. Mechanical shearing induces melt flow and promotes delamination of the oxide layer from the surface of the steel, which boosts the formation of the interface intermetallic phase and results in metallurgical bonding of the interface. The intermetallic layer is composed of the α_c phase near the Al matrix and a thin layer of τ₁₀ phase near the Fe matrix as opposed to the widely reported η phase. The thickness of the intermetallic layer can be controlled by varying the shearing intensity. Both the grain size of the aluminum matrix and the eutectic Si are refined by mechanical shearing, with better refinement effects generated by higher shearing intensity and longer application time. The interface bonding strength is improved by mechanical shearing, which is rationalized by the change in the microstructure.