Microstructural, mechanical, and wear properties characterization and strengthening mechanisms of Al7075/SiCnp composites processed through ultrasonic cavitation assisted stir-casting

In this investigation, Al7075 matrix composites reinforced with nano-SiC particles were manufactured using an ultrasonic cavitation assisted stir casting approach. The microstructural characterization by SEM confirms the presence of nano-SiC particles with all the composites, particle size, and with reasonably homogeneous particle dispersion. Characterization by EDS and XRD confirm no trace of oxide formations, and secondary phase or impurities formations with the composites. Optical microscopic examinations shown matrix phase grain refinement due to the presence of nano-SiC particles as-well-as the aggressive ultrasonic cavitation effect. The mechanical properties of the composites have been substantially improved with an increased amount of nano-SiC particles. The manufactured composites demonstrated an outstanding yield strength of 284 MPa with the only 2.0 wt% reinforcement of nano-SiC particles which is 94.52% improvement compared with the yield strength of the ultrasonically treated Al7075 matrix alloy. The strength of Al7075/SiCnp composites has been estimated by various models of strengthening mechanisms. The strengthening contribution due to thermal mismatch is more dominant followed by Orowan strengthening, Hall-Petch mechanism, and load transferring effect for Al7075/SiCnp composites. The strengthening contributions of CTE difference, dislocations interactions between matrix-reinforcement particles, grain-refinement, and load transfer mechanism increased monotonically for the increased percentage of SiCnp content with the composite. The wear resistance of the composites was found as superior to the matrix alloy and was continuously decreased rapidly up to 750 m of sliding distance while it was protracted up to 2250 m. The composite with 2.0% nano-SiC particles reinforcement has shown approximately 79.8% improvement in wear resistance compared with the matrix alloy.

Automated summary

Al7075 matrix composites reinforced with nano-SiC particles were successfully manufactured using an ultrasonic cavitation assisted stir casting method, resulting in improved mechanical properties with increased nano-SiC particle content. The presence of nano-SiC particles led to matrix phase grain refinement and the dominant strengthening mechanisms included thermal mismatch and Orowan strengthening. The wear resistance of the composites showed significant enhancement compared to the matrix alloy, especially with the addition of 2.0% nano-SiC particles reinforcement.