Effects of Aluminum Content on Oxidation Behavior of W-Al Nanolayer Coatings

A series of W-Al nanolayer coatings were deposited with varying content of aluminum from 0 at.% to 65 at.% by a unbalanced magnetron (UBM) sputtering system. The as-deposited coatings were investigated first. Then, the coatings were oxidized aiming to study their oxidation behavior. SEM, TEM, XRD, GDOS and nanohardness tester were used. The results showed that the Al content had a significant effect on the performance of W-Al coatings. The hardness of as-deposited and oxidized coatings decreased with increasing Al content. The pure W coating was heavily oxidized. As the Al content increased, the oxidation decreased fast and then remained stable as the Al content was higher than 45at.%. The effects of formed oxides on hardness were discussed.