Influence of Annealing on Microstructure and Tribological Properties of AlCoCrFeNiTi High Entropy Alloy Based Coating

Abstract

The primary focus of the study is to explore the influence of annealing on the various properties like phase formation, microstructure evolution and wear analysis of equiatomic AlCoCrFeNiTi high entropy alloy (HEA) coatings developed by atmospheric plasma spray technique. Post deposition, annealing was performed at three different temperatures of 700 °C, 900 °C and 1200 °C, respectively, for a time period of 180 min. X-ray diffraction (XRD) studies revealed that AlCoCrFeNiTi HEA coating comprises two BCC solid solution phases. The deposited samples were characterized using scanning electron microscopy (FESEM), surface profilometer, chemical analysis using x-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). The dilution level study revealed the strong metallurgical bonding between coating and substrate. Microhardness of the AlCrCoFeNiTi was found to be marginally decreased by increasing the annealing temperature due to coarsening of grains and the deposited coating microhardness was found to be 768.48 ± 16 HV0.2. Wear test analysis performed using the ball-on disc test revealed that, there is a significant decrease in wear resistance after heat treatment at 1200 °C. Beyond 900 °C, annealing decreased the microhardness and wear resistance due to coarsening of grains. The wear volume rate of the unannealed as-deposited coating was found to be 2.8 × 10–7 mm3 N−1m−1 and the coating annealed at 700 °C, 900 °C, and 1200 °C had a wear volume rate of about 2.89 × 10–7mm3N−1m−1, 2.87 × 10–7mm3N−1m−1, 7.29 × 10–7mm3N−1m−1, respectively. Graphical Abstract: [Figure not available: see fulltext.]. © 2022, The Author(s) under exclusive licence to The Korean Institute of Metals and Materials.