Laser surface alloying of a novel Nb_11.2Cr_22.2 Co_22.2Ni_22.2Cu_22.2/TiN/VC composite coating: A preliminary parametric study

¹ Chemical, Metallurgical and Materials Engineering, Faculty of Engineering and Built Environment, Tshwane University of Technology, P.M.B. X680, Pretoria, South Africa
² Center for Energy and Electric Power, Electrical Engineering, Faculty of Engineering and Built Environment, Tshwane University of Technology, P.M.B. X680, Pretoria, South Africa
³ Photonic Center, Council for Scientific and Industrial Research, Pretoria, South Africa

^* Corresponding author: ayo.alabi@ymail.com

Abstract

A preliminary investigation was conducted to choose process parameters for laser surface alloying of a novel high-entropy alloy-based composite coating on a steel substrate. The chosen ranges for laser power, scanning speed and powder feed rate are 1500 to 2500 W, 0.4 to 0.8 m/min ute and 0.14 to 0.24 g/minute, respectively. The study examined the effect of powder feed rate and scanning speed on the properties of single beads. B eads' geometrical properties were measured, from which dilution percentage and aspect ratio were calculated. The correlation between microstructure and hardness value was also investigated. The highest combination of desired properties was achieved at 1500 W, 0.4 m/minute and 0.14 g/minute parameter settings. The bead deposited at the optimal condition resulted in dilution percentage, aspect ratio, and hardness value of 80.16%, 14.47, and 447.47 ± 6.60 HV0.3, respectively. It hardness profile across deposited layer interface revealed that hardness values decreased across bead-heat affected zone-substrate interface in the order: 447.47 ± 6.60 HV_0.3 > 339 ± 36.93 HV_0.3 >155.3 ± 1.01 HV_0.3. Scanning electron microscopy revealed excellent bead-substrate melt pool mixing, resulting in good interfacial bonding, cracking, and pore-free microstructure.