Microstructure evolution of V-Al-C coatings synthesized from a V2AlC compound target after vacuum annealing treatment

V2AlC belongs to a family of ternary nano-laminate alloys known as the MAX phases, which exhibit a unique combination of metallic and ceramic properties. In this work V-Al-C coatings with deposited (V,Al)2C nano-crystallines and amorphous phase were magnetron sputtered from V2AlC compound target. The subsequent vacuum annealing for 1 h was carried out at 600 °C, 700 °C and 800 °C, respectively. The crystallization of V2AlC MAX phase was detected by annealing at 600 °C. Meanwhile, a small amount of amorphous carbon phase appeared. Further increasing annealing temperature to 700 °C led to a complete transformation from amorphous V-Al-C phase to V2AlC phase, as well as a significant increase in the amorphous carbon content. It was noticed that the crystallinity of V2AlC phase was significantly enhanced and amorphous carbon was almost disappeared after annealing at 800 °C. The coating toughness became better with the increase in the content of V2AlC MAX phase. The optimized mechanical and tribological properties of the annealed V-Al-C coatings were further discussed in terms of the microstructure evolution.