Fabrication of aluminum/stainless steel bimetallic composites through a combination of additive manufacturing and vacuum-assisted melt infiltration casting

摘要

This paper provides a hybrid method for net shape, lattice based, complex bimetallic composites using a combination of laser powder bed additive manufacturing and vacuum-assisted melt infiltration casting process. 316L stainless steel lattice structures were built using a selective laser melting (SLM) technique. Then, their cavities were filled with an aluminum alloy using vacuum-assisted melt infiltration to yield a bimetallic composite. For comparison purposes, monolithic aluminum alloy was also cast under the same casting parameters. Tensile properties of the fabricated stainless steel lattice and bimetallic composite were found to be insignificantly different. This was explained by the observed continuous gap in the 316L stainless steel/aluminum alloy interfaces which prevented load transfer from the stainless steel lattice to the aluminum matrix during tension. However, compressive properties of the bimetallic composite were found to be significantly greater than those of the stainless steel lattice implying that the aluminum alloy matrix plays an important role during compressive deformation of the bimetallic composites. The monolithic aluminum alloy sample exhibited a noticeably higher elastic modulus, yield stress and ultimate tensile strength but a dramatically lower elongation than both the steel lattice and bimetallic composite specimen. Detachment of the stainless steel lattice from the aluminum matrix was determined to be the root cause of failure for the bimetallic composite in tension.