Tensile Properties of Amorphous Iron-base Alloy (Fe-P-C System)

The elastic, plastic and fracture behaviors under tension and the changes in these properties during and after heating at various temperatures have been studied for amorphous Fe80-P15-C5 alloy. The amorphous specimens were prepared to have a shape of filament about 30μ thick and 0.5 mm wide using a centrifugal quenching apparatus developed in our laboratory. The mechanical tests were performed over a temperature range between −195 and 500°C through a range of strain rates from 6.7×10−5 to 6.7×10−2 per sec. The amorphous alloy exhibits extremely high strengths such as about 230 kg/mm2 in proportional limit and about 310 kg/mm2 in fracture strength. Young’s modulus is about 12.4×103 kg/mm2. Its tensile elongation is only 0.03% at room temperature. The fracture strength decreases as the strain rate increases. The tensile strength and Young’s modulus depend significantly upon temperature and the fracture elongation increases rapidly above about 300°C. The fracture by localized shear deformation occurs over a wide temperature range of −195 to about 300°C and the fracture surface consists of a smooth region produced by shearing and a vein-like region produced by plastic instability. Transformation from the amorphous phase to the crystalline phase results in lower fracture strength, higher hardness and more brittle manner.