Unveiling the effect of vacuum heat treatment on HVOF-sprayed high entropy cantor alloy coatings: Microstructure, diffusion behavior and mechanical property

Abstract

This study explored the effect of vacuum heat treatment on the microstructure and mechanical properties of High-Velocity Oxygen Fuel (HVOF) sprayed Cantor alloy (CoCrFeNiMn) coating. The heat treatment improved the microstructure of the coatings by decreasing the size of the pores. Enhanced diffusion distance at the interface was observed with higher heat treatment temperatures, promoting thorough bonding between the coating and substrate. Besides, recrystallization at high temperatures led to a reduction in grain size and improved uniformity. At 900 °C, the density of geometrically necessary dislocations decreased, while microhardness increased, indicating improved coating integrity and durability. The grain boundary strengthening played a dominant role in the coating heat treated at 900 °C compared to the dislocation strengthening. Therefore, optimizing the heat treatment process for HVOF-sprayed Cantor alloy coatings is essential for reduced defects, achieving sufficient diffusion at the interface, and enhanced coating mechanical properties.

Keywords

• HVOF
• CoCrFeMnNi
• HEA coating
• Vacuum heat treatment
• Microstructure