Microstructural changes of amorphous Mo–B–C coatings upon thermal annealing

Several amorphous Mo–B–C coatings with wide range of compositions were subjected to thermal annealing to a final temperature of 1000 °C in UHV conditions. The nature of the induced recrystallization depended mostly on the Mo content in the coating. A higher Mo content resulted in a nanocrystalline Mo2C phase, a lower Mo content in a nanocrystalline Mo2BC phase and Mo content in-between resulted only in a near-amorphous microstructure. In all cases, the hardness and effective elastic modulus increased significantly after annealing up to values of ∼29 GPa and 500 GPa, respectively. The cobalt diffusion from the WC-Co substrates affected the lower parts of coatings forming a MoCoB interface. •Amorphous Mo–B–C coatings were subjected to thermal annealing to 1000 °C.•The recrystallization of the annealed coatings was governed by the Mo content.•The hardness and elastic modulus increased significantly up to 29 GPa and 500 GPa.•The MoCoB interfacial layer was formed between the WC-Co substrate and the coating.