Microstructure and Properties of Laser Cladding WC Reinforced Ni-Based Alloy Cladding Layer on AlSi7Mg Aluminum Alloy Surface

Single-track and multi-track WC reinforced Ni-based alloy cladding layers were prepared on surface of AlSi7Mg aluminum alloy by laser cladding. The microstructure, phase composition, dilution ratio and microhardness of the cladding layers were investigated. The results show that when the laser scanning speed increased from 3.3 mm·s^-1 to 6.0 mm·s^-1, pores and cracks in the single-track laser cladding layer became less. At the scanning speed of 4.6 mm·s^-1, spot diameter of 1.0 mm and overlap of 20%, the WC particles in the multi-track cladding layer mainly distributed at interface between the cladding zone and transition zone, and the cracks and pores were located at the overlap and the bottom of the cladding layer, respectively. The dilution ratios of the first-track cladding layer and the last-track (the fifth-track) cladding layer were 10% higher than those of the second-track to fourth-track cladding layers. Intermediate phases, such as AlNi, Al₃Ni, M₇C₃ and M₂₃C₃, were formed in the WC reinforced Ni-based alloy cladding layers. The average dilution ratio of the layers was about 45% and the microhardness was about 1 100 HV.