Interfaces and properties of Al-Si alloy zircon particulate composites

摘要

Zircon-particle-dispersed Al-13.5Si-2.5Mg is a structural composite material being investigated for lightweight, tribological applications. The conventional, powder-processed material, in the temperature range of 22-100 degrees C, yielded a low coefficient of linear thermal expansion (CTE) of 7.8 x 10(-6) degrees C at 0.15 volume fraction (V-f), a 64 reduction of that of the alloy. The dry sliding wear rate and the coefficient of friction measured by the pin-on-the-plate technique at 4 kg load decreased significantly by 99 and 35.5, respectively. A significant reduction, by 29, in wear rate of the alloy was observed to occur only when more than 0.03V(f) zircon was dispersed. An x-ray study showed that the interface reaction products consist of compounds of Mg, Ce, Cu, and Nb. Tensile failure of the reaction-sintered parts revealed a ductile mode of fracture, with the path traversing both through voids and the bonded particles while interface failure was observed in parts without Mg. An analysis of both the tribological and tensile properties showed that an optimal performance of this alloy at 0.15V(f) zircon is achieved when the Mg content is between 2.5 and 3.5 wt. . References: 23