Effect of TiB₂ on the wear resistance of cast Al-Zn-Mg-Cu alloys

The influence of TiB₂ on the microstructure, hardness, and wear resistance of Al-Zn-Mg-Cu/TiB₂ composites was systematically investigated in this study. Multi-scale characterization techniques were used to analyze the distribution of TiB₂ particles, their interfacial structure, and their interactions with precipitates. The results indicated that the incorporation of an appropriate amount of TiB₂ particles significantly refined the resulting grain structure. The agglomerated TiB₂ particles formed a distinctive network-like architecture, which effectively transferred and dispersed applied loads, leading to a multi-scale synergistic strengthening effect. A composite with 2.5 wt. % TiB₂ exhibited approximately 17.2 % and 31.2 % improvements in modulus and hardness, respectively, compared to a reference Al-Zn-Mg-Cu alloy. A composite with 4 wt. % TiB₂ demonstrated optimal wear resistance, with a wear reduction of about 47.3 % relative to the Al-Zn-Mg-Cu alloy. It was found that the dominant wear mechanism transitioned from a mixed wear mode to mild adhesive and abrasive wear. From the perspectives of microstructure and crystallography, this work elucidated the synergistic mechanism by which TiB₂ content influenced the strengthening and wear behavior of aluminum composites, providing a theoretical foundation for the design and fabrication of high-performance wear-resistant aluminum matrix composites.