Influence of high current pulsed electron beam on microstructure and properties of Ni–W alloy coatings

Abstract

Ni–W alloy coating layers were successfully materialized through an innovative surface alloying approach, high-current pulsed electron beam (HCPEB) irradiation. Two levels of HCPEB irradiation, 10 and 20 pulses, were applied to tungsten powders coated on nickel substrate. In the case of 10 pulses HCPEB irradiated sample, surface defects were formed on the Ni–W alloy surface layer. As the number of HCPEB pulse increased to 20, the surface became much smoother as compared to that of 10 pulses irradiated one. During irradiation, W particles were dissolved into the Ni substrate, and the newly formed Ni–W alloy layer was mainly composed of two major phases, NiW and Ni. After HCPEB irradiation, the microhardness was significantly increased, and the coefficient of friction (COF) and wear rate were reduced, which is attributed to the ultrafine W particles formed in the Ni substrate. Moreover, the corrosion property was enhanced after HCPEB irradiation.