Improved the elevated temperature mechanical properties of Al-Si alloy deposited with Al-Si coating by magnetron sputtering

Compact and uniform aluminum silicon (Al-Si) coatings with different Si contents were deposited on Al-Si alloy by magnetron sputtering. The structure and mechanical properties of the Al-Si alloy covered with Al-Si coating were characterized. The results indicate that the introduction of Al-Si coating on Al-Si alloy surface can increase the mechanical properties of Al-Si material. Hardness and elastic modulus of the Al-Si coating with 25.2 at % Si reach about 23.6 GPa and 178.0 GPa, respectively, which are obviously higher than those of Al-Si bulk. The Al-Si coating with 25.2 at % Si exhibits the lowest friction coefficient of 0.231 and lowest wear rate of 0.9-1.4 × 10−6 mm3/Nm. The low friction coefficient of Al-Si coating is attributed to the Al and Si debris which react with thermal moisture to form aluminum and silicon oxide, serving as a lubricant between two contact counterparts.