Development of highly wear resistant Cu - Al alloys processed via powder metallurgy

Abstract

Abstract The present work explores the effect of aluminium (Al: 0, 3, 5, 10 & 15 wt%) addition on wear behaviour of copper (Cu). The Cu-Al alloys were fabricated via mechanical alloying and high-pressure hot press. In fact, high-pressure processes are beneficial as they result in obtaining fine microstructure and property enhancement. Depending on the amount of Al, the microstructure of hot pressed samples (Cu with Al up to 5 wt%) consisted of copper-rich solid solution phase (Cu0.92Al0.08) and the presence of both Cu0.78Al0.22 and Cu9Al4 intermetallic phases for Cu containing high amount of Al (≥10 wt%). The relative density of Cu-Al alloys varied between ∼95 and 98% and the hardness of Cu enhanced significantly from 1.32 to 6.16 GPa with Al content. The coefficient of friction (COF) (0.54 to 0.16) and wear rate (18.26 × 10−5 to 0.92 × 10−5 mm3/N-m) of Cu decreased with the addition of Al. A transition in wear mechanisms of Cu was observed with Al. In case of pure copper, adhesion was the major wear mechanism. Adhesion and tribo-oxidation controlled the wear of Cu alloyed with Al (up to 5 wt%). Oxide layer formation influenced the wear of Cu-10Al, while abrasion was the predominant wear mechanism for Cu-15Al. These results clearly indicate the advantage of large amount of Al addition to achieve better wear resistance of Cu.