Different reinforcement strategies of hybrid surface composite AA6061/(B4C+MoS2) produced by friction stir processingVerschiedene Strategien beim Ruhrreibschweissen zur Verstarkung von Hybrid-Oberflachenverbundwerkstoffen aus AA6061/(B4C+MoS2)

Aluminum surface composites have gained huge importance in material processing due to their noble tribological characteristics. The reinforcement of solid lubricant particles with hard ceramics further enriches the tribological characteristics of surface composites. In the current study, friction stir processing was chosen to synthesize hybrid surface composites of aluminum containing B4C and MoS2 particles with anticipated improved tribological behavior. B4C and MoS2 powder particles in 87.5: 12.5 ratio were reinforced into the AA6061 by hole and groove method. Microstructural observations indicated that reinforcement particles are well distributed in the matrix. The hardness and wear resistance of hybrid surface composites improved as compared to the base material, due to well distributed abrasive B4C and solid lubricant MoS2 particles in AA6061. The hybrid surface composites achieved similar to 32 % increased average hardness as compared to the base material. Hole method revealed similar to 13 % better wear resistance compared to the groove method for friction stir processed hybrid surface composite, attributing to an improved homogeneity of particle distribution shown by zigzag hole pattern. Moreover, friction stir processed AA6061 without reinforcement particles exhibited reduced hardness and wear resistance due to loss of strengthening precipitates during multi-pass friction stir processing.