Wear of aluminium-base materials processed by mechanical milling in air or ammonia

Abstract The tribological behaviour of mechanically alloyed (MA) aluminium-base materials has been studied as a function of processing methods. In particular, a new sintered MA aluminium material, milled under an ammonia atmosphere (MA Al-NH 3 ) and consolidated by a single cycle of cold compaction and sintering, is compared with conventional MA aluminium (MA Al-air), milled in confined air and consolidated by a double cycle of compaction and sintering. The wear behaviour of the aluminium-base materials has been studied in a pin-on-disk tribometer, sliding against AISI 52100 steel pins. Dry wear tests have been carried out under variable load and temperature, to show that milling conditions, specifically milling atmosphere, have a strong influence both on mechanical properties and wear resistance. The higher wear resistance of MA Al-NH 3 with respect to MA Al-air increases with the severity of the contact conditions. Wear mechanisms are discussed from SEM observation of wear tracks, wear debris morphology and transfer tribolayers.