In-Situ Al-Mg Alloy Base Composite Reinforced by Oxides and Intermetallic Compounds Resulted from Decomposition of...

In the presented work, the effect of friction stir processing admixing the zirconium tungstate ZrW₂O₈ 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-ZrW₂O₈ underwent the following changes: (i) high-temperature transformation into metastable β'-ZrW₂O₈ and (ii) decomposition into WO₃ and ZrO₂ oxides followed by the formation of intermetallic compounds WAl₁₂ 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 Al₂O₃, ZrO₂, β'-ZrW₂O₈ and intermetallic compounds such as WAl₁₂ and ZrAl₃. Potential applications of the above-discussed composites maybe related to their improved tribological characteristics, for example in aerospace and vehicle-building industries.