Dry wear of NiAl3-reinforced mechanically alloyed aluminium with different microstructure

The tribological behaviour of mechanically alloyed (MA) aluminium-base materials reinforced by 2 vol.% NiAl3, either as large lamellae (MA Al-Ni S) or as homogeneously dispersed rounded particles (MA Al-Ni S2) has been studied. The results are compared with that of nickel-free MA aluminium (MA Al S), taken as reference. All materials were prepared by mechanical milling of Al powder, eventually with the addition of 1 wt% Ni powder, followed by consolidation techniques of cold compaction and sintering. Tribological tests were carried out using the pin-on-disc configuration under variable normal load and temperature. MA Al-Ni S2 shows the highest wear reduction with respect to MA Al-Ni S at the highest load studied. At low load and high temperature, MA Al-Ni S2 shows the highest wear rate, probably due to severe abrasion of the steel counterpart. Friction values and wear mechanisms are discussed from SEM observations and EDS analysis of wear tracks, wear debris morphology and transfer tribolayers.