Effect of Squeeze Casting Pressure on the Interdiffusion Zone Characteristics of the Aluminum-Copper Bimetallic Layer

Abstract

Bimetals are composite materials created by combining two different metals with metallurgical bonding at their interface. Squeeze casting is one of the promising methods for bimetal manufacture; however, the optimum pressure required to achieve desirable mechanical properties is still under development. This study aims to determine the casting pressure that produces an optimal interdiffusion bond at the aluminum–copper interface. In this work, aluminum and copper alloys were used, with aluminum melted at 750 °C and copper at 1150 °C. The process was carried out by sequentially pouring molten metals into the mold. Copper was poured first, and once partial solidification occurred, aluminum was subsequently poured, forming an Al–Cu bimetal bushing. Pressure was applied during the first frozen layer stage, with variations of 60, 70, 80, and 90 MPa. Results revealed that applying greater pressure promotes the development of a thicker interdiffusion layer. The interface region exhibited the highest hardness and wear resistance due to the in-situ formation of AlCu, Al₂Cu, and Al₄Cu₉ compounds. Therefore, Al–Cu bimetal can be effectively produced by squeeze casting at 90 MPa, resulting in an optimal interdiffusion zone at the interface.