Cladding AA7075 with a cryomilled Al-12Si alloy using spark plasma sintering

A eutectic Al-Si cladding was formed on the surface of a wrought aluminum alloy 7075. The cladding was formed by simultaneous sintering and joining of the powder to the substrate surface. Interfacial strength and properties of the cladding were investigated, as well as the effect of sintering on the substrate properties. A minimum thickness of 1 mm for the cladding process was found in order to maintain the mechanical properties. During sintering, diffusion of Si, Zn, Mg and Cu across the interface occurred, upwards of 200 μm into the cladding. The sintering process resulted in a drop in the hardness of the substrate, which was recoverable by solutionizing and subsequent artificial aging. Three-point bending was used to test the strength of the interface formed between the two materials and an average flexural strength was determined to be 260±31 MPa with an average strain to failure of 0.36±0.09%.