The influence of nickel coating thickness on interlayer morphology of steel wires in A413 matrix composite via lost foam casting

In this study, the effect of nickel coating and thickness of coating on interlayer microstructure were studied, by inserting the Ck7 steel wires with diameter of 1.5 mm, with 10 and 2μm thickness coatings, into polystyrene patterns, followed by pouring the aluminum melt. The composite interface was studied by optical microscope and Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy system. No metallurgical bonding is formed between A413 melt and mild steel wire of 1.5mm diameter without Ni coating. An air gap is also observed between the wire and the matrix. Wettability characteristics of the reinforcement with the A413 melt will be improved by nickel coating. Both samples with 2 and 10μm thick coated wires will experience formation of intermetallic layers at the interface. Three distinct layers will be formed in both samples with 2 and 10μm thick coated wires. The interlayer for the sample with 2μm thick coated wire, from the core toward the matrix, includes phases of τ11-Al5-Fe2Si, τ2-Al3FeSi (γ) and τ6-Al4.5FeSi (β), respectively. neither the nickel coating remains on the reinforcement nor the interphases within reinforcement/matrix interface includes nickel. The interlayer for the sample having 10μm thick coated wire, from steel toward the matrix, includes phases of τ11, τ2 and τ1-Al9FeNi, respectively. some cracks have been formed through the interlayer as well.