Effect of Aging and Rolling on Microstructure and Mechanical Properties of AA7075/TaC Composites

The present study aims to develop aluminum metal matrix composites (AA7075) reinforced with varying proportions of Tantalum Carbide (TaC) from 0.1-0.5 wt.% using rheo stir casting process. The effects of secondary processes such as solutionizing heat treatment, and rolling at different conditions were further examined on AA7075/0.5TaC composite. The microstructural analysis shows that the addition of TaC in AA7075 matrix induced grain refinement due to the pining effect. The gradual increment in the mechanical properties was observed with an increase in TaC addition. The highest microhardness of 96 Hv, yield strength (YS) of 171 MPa, and ultimate tensile strength (UTS) of 205 MPa were observed for the composite containing 0.5 wt.% TaC owing to dispersion strengthening mechanism. Rheo stir casting process resulted in enhanced densification and particle distribution of AA7075/TaC composites. The secondary phases were dissolved using homogenization treatment, leading to higher hardness due to precipitation hardening. Among all rolling processes, the cryo-rolled specimen with 70% thickness reduction achieved the highest hardness of 165 Hv as a result of suppression of dynamic recovery. The effect of the strengthening mechanisms on YS was analyzed and the analysis revealed that experimental YS is bigger than the theoretical YS.

Automated summary

The present study aimed to develop aluminum metal matrix composites (AA7075) reinforced with varying proportions of Tantalum Carbide (TaC) using rheo stir casting process. The microstructural analysis showed that the addition of TaC induced grain refinement in AA7075 matrix. The mechanical properties, such as microhardness, yield strength, and ultimate tensile strength, increased with the increase in TaC addition. The rheo stir casting process resulted in enhanced densification and particle distribution of AA7075/TaC composites.