Interface stability in vacuum infiltrated stainless steel and nichrome reinforced aluminium composites

An experimental study of interface reactions (IR) in Al reinforced with stainless steel or nichrome wires is reported. Composite with up to 60 vol percent 152-micron-diameter fibers in commercial Al or Al/10-wt-percent-Mg matrices were prepared by vacuum infiltration, exposed to temperatures from 200 to 650 C for intervals up to 100 h, and examined under the microscope. The results are illustrated with photomicrographs. In the as-cast state, no IR is observed except in the Al/Mg-matrix composites. In the steel-reinforced Al composite, IR products (IRP) grow at isolated places on the fiber surface at temperatures above 450 C, covering the entire interface only after long periods or at temperatures near the melting point. IRP growth proceeds outward and has a minimal effect on ultimate tensile strength. In the nichrome-reinforced Al composite, IRP appear after 25 h at 350 C and grow inward, completely damaging the fiber in 100 h; the ultimate tensile strength decreases sharply as soon as the IRP appear