Tribological behavior of AlSn20Cu alloy manufactured by additive friction stir deposition

Al-Sn alloy is utilized as a bearing material to replace conventional Sn-based alloy in the design of bearing liners due to its higher load-carrying capacity and wear resistance. However, cracks readily initiate in casting Al-Sn alloy near the coarse Sn phase, leading to low mechanical properties and insufficient wear resistance. The present study introduces a new method, additive friction stir deposition (AFSD), to produce AlSn20Cu alloy with fine grains and sub-micron-scale Sn phases, resulting in enhanced mechanical performance and wear resistance. Compared to both casting and cold rolling + annealing AlSn20Cu alloys, the ultimate tensile strength of AFSD AlSn20Cu alloy is improved by 80.56 % and 16.67 % respectively. Additionally, AFSD AlSn20Cu alloy demonstrates a lower coefficient of friction (COF) and lower wear rate without significant subsurface damage. This is attributed to the fine and uniformly distributed Sn phase forming a uniform and dense surface lubrication layer that adapts the friction pair to the boundary lubrication state, preventing the initiation and development of cracks.