Characterisation and tribological evaluation of a nickel surface alloyed aluminium-based material

Electron beam nickel surface alloying of LM13, a near eutectic Al–Si-based material, was carried out. The alloying resulted in the formation of a surface layer with about 25 wt.% nickel in the form of hard nickel aluminide (NiAl3) dendrites. The overall hardness of the layer was about 340 HV. The sliding wear and friction properties of the treated material was then measured by means of a pin on disc wear testing machine, using a steel ball (hardened in excess of 750 HV) as the counterface. The results showed significant increase in the wear life of LM13 after surface alloying. The alloying also changed the mode of wear from a predominantly adhesive mode, in the case of unalloyed LM13, to a mainly abrasive wear mode. Nickel alloying also reduced the coefficient of friction, which could otherwise be higher because of the strong adhesion of aluminium to steel.