Abstract
In the presented work, the effect of friction stir processing admixing the zirconium tungstate ZrW(2)O(8) powder on the microstructure, mechanical and tribological properties of the AA5056 Al-Mg alloy stir zone has been studied. The FSP resulted in obtaining dense composite stir zones where α-ZrW(2)O(8) underwent the following changes: (i) high-temperature transformation into metastable β'-ZrW(2)O(8) and (ii) decomposition into WO(3) and ZrO(2) oxides followed by the formation of intermetallic compounds WAl(12) and ZrA(l3). These precipitates served as reinforcing phases to improve mechanical and tribological characteristics of the obtained fine-grained composites. The reduced values of wear rate and friction coefficient are due to the combined action the Hall-Petch mechanism and reinforcement by the decomposition products, including Al(2)O(3), ZrO(2), β'-ZrW(2)O(8) and intermetallic compounds such as WAl(12) and ZrAl(3). Potential applications of the above-discussed composites maybe related to their improved tribological characteristics, for example in aerospace and vehicle-building industries.