Preparation and properties of foamable Ni-GNP/AlSi12 Precursor Materials

In this study, nickel-coated graphene nanoplatelets reinforced AlSi12 precursor materials were produced by powder metallurgy method. For this process, Ni-GNP particles were added to the matrix material AlSi12 powders at different ratios (0%, 0.4%, 0.8% and 1.2% by weight). Then, the mixed powders were cold compressed and extruded at different ratios, and foamable precursor samples with diameters of 6 and 12 mm were produced. Microstructural analyses, density measurements and microhardness tests were carried out to evaluate the effects of Ni-GNPs on the properties of foamable precursor materials. Microstructure and surface analysis of Ni-GNP/AlSi12 precursor materials showed high density, uniform distribution of Ni, localized Si phases and surface oxidation due to reactivity of aluminum. It was revealed that the addition of Ni-GNP led to the formation of Al-Ni intermetallic phases, reduced the Al peak intensity and strengthened the graphene bond with the Al matrix. The relative density increased with increasing extrusion ratio, higher Ni-GNP content decreased the relative density but improved it significantly after extrusion. The maximum hardness was achieved in the precursor materials with the optimum graphene content of 0.4 wt%, while higher amounts led to aggregation, increased porosity and decreased hardness.