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ABSTRACT: Alumina (Al[sub 2]O[sub 3]) particles reinforced aluminum matrix composites have recently become candidates for structural materials because of their good specific modulus and strength, and are considered to be valuable materials for aerospace and automobile industry applications. In view of such application, they might be processed or applied in high strain rate loading conditions, such as explosive forming, blast loading and metalworking, etc. Knowledge of the mechanical behavior of the metal matrix composites under high strain rate loading is a prerequisite. However, not much work related to this topic has been done. The objective of this study was to investigate the effect of the strain rate on the tensile properties of the Al[sub 2]O[sub 3p]/6061-T6 composite at low temperatures.
Scripta Metallurgica et Materialia; (United States). 07/1993; 29:3.
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ABSTRACT: The metal matrix composite materials consist of 10, 15 and 20 vol.% alumina particles in an aluminium alloy 6061-T6 matrix. Specimens were taken from hot-extruded rods and the tensile tests were carried out at various strain rates. High strain rate tests were performed by the split-Hopkinson-bar method. The fracture surfaces were observed with a scanning electron microscope to understand the fracture mechanisms. From the results, it can be concluded that: (1) the alumina-reinforced composites are more sensitive to strain rate than the unreinforced material, (2) the strain rate sensitivity of the ultimate tensile strength of these composites increases with increasing temperature and (3) the addition of alumina particles will reduced the ductility of aluminium alloy 6061-T6, irrespective of the strain rate and temperature.
Materials Science and Engineering: A.
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ABSTRACT: The effects of austempering temperature and isothermal transformation time on the low-cycle fatigue (LCF) behaviour in ductile irons have been studied. The fracture surfaces were observed by a scanning electron microscope in order to understand the fracture mechanism of LCF. From the results, it can be concluded that the best LCF behaviour is for the irons austenitized at 950 °C and there is very good cyclic stability at the lower strain amplitude irrespective of the austempering condition. However, there is a little cyclic softening at higher strain amplitudes for all the austempering conditions. Under a larger strain amplitude, the best LCF behaviour is for the specimen that has undergone austempering at a higher temperature, but under a smaller strain amplitude, the best LCF behaviour is for the specimen austempered at 350 °C.
International Journal of Fatigue.
