Microstructure and Wear Properties of Ni-based Composite Coatings on Aluminum Alloy Prepared by Laser Cladding

The microstructure and wear properties of Ni-based composite coatings on aluminum alloy prepared by laser cladding were investigated by SEM, EDS, microhardness tester and friction tester. The results show that there are relatively few holes and cracks in the layer when the scanning speed is 5 mm/s. Many massive and continuous network Ni-Al intermetallic compounds form on the top of the cladding layer, and (Ni, Cr, Fe)xCy intermetallic compounds form at the middle of the cladding layer. The microstructure of the bottom cladding layer consists of the columnar α-Al dendrite with obvious growth direction. The middle and top of the cladding layer maintain a high microhardness value. The maximum microhardness of the middle of layer is 8200 MPa, which is more than 5 times larger than that of the bottom cladding layer. The microhardness decreases sharply at the end of the middle of layer. The friction coefficients of the layer have a fluctuation under different loads, and decrease with increasing the load. The formation and distribution of Ni-Al and (Ni, Cr, Fe)xCy intermetallic on the top and middle of the cladding layer are the primary reason for the improvement of the microhardness and wear of the layer. Copyright © 2020, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.