In-situ Particulate-Reinforced Al Matrix Composites: Effect of the Synergistic Mechanism of ZrB2 and Al3Zr on Tribological Behavior

Abstract To investigate the key factors that cause ZrB 2 /AA6111 and (ZrB 2 +Al 3 Zr)/AA6111 aluminum matrix composites (AMCs) made via in situ reaction to behave differently in terms of friction and wear. Room-temperature dry sliding tribological behavior of AA6111 Al alloys, ZrB 2 /AA6111, and (ZrB 2 +Al 3 Zr)/AA6111 AMCs against silicon nitride (Si 3 N 4 ) counterparts were investigated. The study showed that AA6111/Al alloy had the highest wear rate and the most unstable coefficient of friction (COF), indicating the worst abrasion resistance. (ZrB 2 +Al 3 Zr)/AA6111 AMCs exhibit a lower wear rate and higher COF than ZrB 2 /AA6111 AMCs. The result proved that the Al 3 Zr particles prepared by the in-situ reaction are strongly bonded (lattice misfit δ =2.7%) to the Al matrix and are not easily stripped from the substrate. ZrB 2 /AA6111 AMCs exhibited a lower COF attributed to the tribochemical reaction inducing the formation of more boric acid (H 3 BO 3 ) films with a graphite-like structure having a lubricating effect.