An investigation into aluminum-aluminum bimetal fabrication by squeeze casting

Aluminum-aluminum bimetal were prepared by casting liquid A356 aluminum alloy onto 6101 aluminum extrusion bars and solidifying under applied pressure. The effect of surface treatment, pouring temperature and applied pressure on microstructure and mechanical properties of the bimetal was investigated. The results showed that sound metallic bonding could be produced by electro-plating the solid 6101 aluminum alloy with a layer of zinc coating and carefully controlling the casting temperature. With the application of pressure during solidification process, the tensile strength exhibited more promising results than that made by gravity casting, for both A356 aluminum alloy matrix and bimetal. However, with the increase of applied pressure, A356 aluminum alloy matrix and bimetal showed different behaviors. For A356 aluminum alloy matrix, the tensile strength increased with the increase of applied pressure, for bimetal it appeared to be independent on the magnitude of the applied pressure and the value remained steady. The fracture analysis indicated that during the tensile test of bimetal, the crack initiation began with initial fracture of eutectic Si in the transition zone then extended in the transition zone. The tensile strength of the bimetal fabricated by squeeze casting method was improved by about 10%, from 145 MPa to 155 MPa, as compared with that made by gravity casting. The process presented in this study provides a promising and effective approach to create a metallic bonding between an aluminum insert and various aluminum melts to develop advanced functional and structural materials. (C) 2014 Elsevier Ltd. All rights reserved.