The influence of Y additions on the microstructure and mechanical properties of MoTaWNb refractory high entropy alloy films by magnetron sputtering

The films of (MoTaWNb)1-xYx high entropy amorphous alloy were successfully deposited by direct current magnetron sputtering under different contents of Y additions. The microstructure, mechanical properties, and friction behaviors of the as-deposited (MoTaWNb)1-xYx films were investigated. The results show that the films were mainly composed of amorphous and body-centered cubic (BCC) phases, and the proportion of the amorphous phase increases gradually with the increase in Y content. When the deposited film has a typical amorphous phase with a uniform and dense fibrous-shaped columnar microstructure, it shows a maximum nano-hardness of 6.74 GPa. However, the growth of V-shaped columnar microstructures during film deposition increases its surface roughness and decreases its mechanical properties. Abrasion wear, oxidation wear, and delamination wear dominate the wear process, and the evolution of the frictional behaviors of deposited films is directly related to their structural and mechanical changes. The wear resistance of (MoTaWNb)1-xYx films with wear rates of the order of 10−5 mm3·N−1·m−1 is achieved by tuning the Y additions, and this film can be used as a potential candidate for wear-resistant coatings.