Manufacturing of Bulk Al-12Zn-3.7Mg-1Cu Alloy with TiC Nanoparticles

Abstract

Aluminum alloys are significant in various applications, and the desire is strong to develop higher strength with balanced other properties out of high Zn and Mg contents in aluminum. However, high contents of Zn and Mg will make the matrix brittle and incompatible for mass manufacturing. As nanoparticles could effectively and dynamically control the brittle secondary phases, it opens a new route to design and manufacture high-Zn and high-Mg aluminum alloys. Here, we demonstrate the feasibility of nanomanufacturing of Al-12Zn-3.7Mg-1Cu alloy system with the help from TiC nanoparticles for potential ultrahigh-strength light-weight alloys. By applying the “hot rolling-natural aging” and “solution treatment-natural aging” processing routes, Al-12Zn-3.7Mg-1Cu alloy with TiC nanoparticles can achieve higher microhardness via natural aging and better machinability when compared with the pure Al-12Zn-3.7Mg-1Cu alloy. Microstructure and thermodynamic studies reveal that the reasons for the peak hardness difference of Al-12Zn-3.7Mg-1Cu alloy and Al-12Zn-3.7Mg-1Cu/1.5 vol.% TiC nanocomposites are due to the free energy difference by solution treatment temperature and the strain energy sustained by the residual secondary phases. The enhanced mechanical properties in Al-12Zn-3.7Mg-1Cu alloy with TiC nanoparticles at the peak-microhardness state after “solution treatment-natural aging” processing route prove the feasibility of the abovementioned nano-treating manufacturing method.