Effect of nano-TiC/TiB2 and final thermo-mechanical treatment on microstructure and properties of 7185 alloy

Abstract

In this study, a new generation of ultra-high strength 7185 aluminum alloy and nano-sized TiC+TiB2 particles reinforced 7185 alloy matrix composites (PRAMCs) were prepared, and its thermos-mechanical treatment (TMT) was studied. The electron probe microanalyzer, electron back scattered diffraction, and transmission electron microscope are used to study microstructure evolution. Tensile tests are used to investigate the mechanical properties of composite materials. The results showed that the grain can be refined significantly by adding particles. The grain size of the quenched state is very fine. The strength and plasticity of the alloy are significantly improved. After the final TMT, many dislocations were introduced, and the precipitation phase and dislocation intertwined with each other during the aging process. This increased the dislocation density and promoted the precipitation process. Thus, the strength and corrosion resistance are improved, but the plasticity is reduced. The yield strength, tensile strength, and elongation of the PRAMCs designed in this study after final TMT are 483.6MPa, 520.4MPa, and 9.1%, respectively. The inter-granular corrosion layer depth is 47.2 μm. The the grade of exfoliation corrosion for 6h and 24h is PC, and EA, respectively. This study can provide strategies for the performance optimization of PRAMCs.