TENSILE, FATIGUE AND IMPACT PROPERTIES OF THE AA 2618/AL_2O_(3P) COMPOSITES

摘要

In this paper, the tensile properties (at RT and 200℃), high cycle fatigue and impact behaviour of the 2618 aluminium alloy reinforced with 5% wt. of Al_2O_3 particles (AA 2618/Al_2O_(3p)/5P) and 10% wt. of Al_2O_(3p)articles (AA 2618/Al_2O_(3p) /10P) were studied. The Composites were prepared by two-step mixing of stir casting method followed by forging. A significant increase in tensile strength of the MMCs, with respect to the unreinforced alloys was evidenced by the tensile test while the elongation to fracture decreased. Tensile property at 200℃ is higher than the unreinforced counterpart. The high cycle fatigue tests showed that fatigue life is comparable to the monolithic alloy. The SEM analysis of the fracture surfaces showed that the presence of secondary precipitates played a significant role in the mechanism of failure in composites by promoting void nucleation at the particle-matrix interfaces, interfacial decohesion and also the failure of the particles. The impact strength is reduced with respect to the unreinforced alloy.