Tsuyoshi Masumoto1 and Hiroshi Kimura2
1The Research Institute for Iron, Steel and Other Metals, Tohoku University, Sendai
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 30 μ 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.
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