Influence of Heat-treatment on Structure and Properties of Electroless Ni-W-P Plating on Aluminium Alloy

The influence of heat-treatment on structure and properties of electroless Ni-W-P deposits on aluminium alloy was investigated using scanning electron microscopy,energy dispersive spectrometer and transmission electron microscopy techniques.The results show that the inter-diffusion between the deposits and substrates is mainly the diffusion of Ni into aluminium alloy during the heat treatment.After specimen heat treated at 525 ℃ for 1 h,the diffusion length of Ni into aluminium alloy is about 10 μm and Ni-Al alloy layers composed of two layers are obtained.The first Ni-Al alloy layer mainly containe Ni2Al3,and the second layer mainly contain NiAl3.Under the dry friction condition,the Ni-W-P deposits heat treated at 525 ℃ for 1 h possessed outstanding wear resistance due to Ni-Al alloy layers obtained.