Significant improvement of wear properties by creating micro/nano dual-scale structure in Al–Sn alloys

We present in this work evidence that significant improvement of wear behavior can be achieved by creating a dual-scale structure. An Al–12 wt%Sn bearing alloy consisting of mixtures of nanocrystalline (NC) Al–Sn powder and coarse-grained (CG) Al–Sn powder was produced by a combination of mechanical alloying and conventional powder sintering. The extent of the improvement in wear properties was related to the ratio of NC/UFG to CG, and the best properties were achieved at a ratio of 30 wt% CG. With this ratio, this dual-scale Al–Sn (CG-30) alloy had a wear resistance about 1.5 times greater than that of the monolithic NC/UFC alloy prepared by mechanical alloying, about twice that of the monolithic CG alloy. The friction coefficient decreased by nearly 13% of the CG alloy. The detailed wear mechanism investigation revealed that an optimized combination of hardness and toughness is a key for the improvement of wear properties in the dual-scale material.