Effect of Si content on the microstructure and mechanical properties of Mo-Al-Si-N coatings

► Mo-Al-Si-N coatings were synthesized using dc magnetron sputtering. ► Mo-Al-Si-N coatings were consisted of nanocrystalline Mo-Al-N and amorphous Si3N4. ► The hardness reaches a maximum of 36 GPa at the silicon content of 8.3 at.%. ► Mo-Al-Si-N coatings are in compressive stress state, with maximum value of 1.8 GPa.