Enhancing ultrahigh-strength aluminum alloys via TiC nanoparticle-pinning effect in friction rolling additive manufacturing

Abstract

Friction rolling additive manufacturing (FRAM) is offers an effective approach for producing high-performance aluminum alloy parts. However, achieving ultrahigh-strength aluminum alloys is difficult owing to the softening behavior of materials during solid-phase deposition and abnormal grain growth during heat treatment. In this study, a strategy for improving the microstructure and preparing ultrahigh-strength aluminum alloys using the pinning effect of TiC nanoparticles on grain boundaries is proposed. The results show that compared with 7075‑aluminum alloy, TiC nanoparticles enhanced dynamic recrystallization during friction roll additive manufacturing, thereby reducing the deposited grain size from 3.13 to 2.60 μm and inhibiting the abnormal grain growth during heat treatment, thereby reducing the grain size from 6.05 to 3.53 μm. In addition, the addition of TiC nanoparticles promoted the precipitation and refinement of the η’-MgZn₂ phase during heat treatment. A 7075-TiC alloy prepared using this method exhibited excellent mechanical properties. After heat treatment, the tensile strength (UTS), yield strength (YS), and elongation (EL) were 626 ± 15.0 MPa, 546 ± 5.2 MPa, and 15.5 ± 0.5 %, respectively, achieving a good synergistic effect on strength and plasticity. Precipitation strengthening played a key role in enhancing the mechanical properties of the 7075-TiC alloy.