Dry sliding wear behaviour of powder metallurgy Al–Mg–Si alloy-MoSi2 composites and the relationship with the microstructure

The effect of the microstructure on the dry sliding wear of six aluminium alloy 6061 matrix composites reinforced with 15 vol.% of MoSi2 particles and two monolithic 6061 alloys processed by powder metallurgy with and without ball milling has been studied. Wear testing was undertaken using pin-on-ring configuration against an M2 steel counterface at 0.94 m/s and normal load of 42, 91 and 140 N. The wear resistance of the aluminium alloys was significantly improved by ball milling and the addition of reinforcing MoSi2 particles due to a more stable and more homogeneous microstructure, which avoids the detachment of the mechanically mixed layer. Wear rate of materials in T6 decreases as solutionized hardness of the materials increases. This behaviour is rationalized by taking into account the precipitation state of the matrix. In addition, wear rate follows a Hall–Petch type relationship, showing that the reduction of matrix grain size plays an important role in the increase in the wear resistance of the composites. The results indicate that the present intermetallic reinforced composites can be considered potential substitutes for ceramic reinforced aluminium alloys in tribological applications.

Research highlights► AA6061/MoSi2/15p composites have a much higher wear resistance than the matrix alloys. ► MoSi2 intermetallic particles delay the transition to severe wear regime. ► Wear resistance is significantly improved by ball milling of the composite powders. ► Wear resistance improves with small reinforcing size and high distribution homogeneity. ► Wear rate obeys a Hall–Petch relation with matrix grain size and solutionized hardness.