Microstructure and mechanical properties of Al-Mg-Ti-B coatings prepared by high power impulse magnetron sputtering (HIPIMS) at room temperature

In this work, Al-Mg-Ti-B coatings were synthesized at room temperature via high power impulse magnetron sputtering (HIPIMS). The as-deposited Al-Mg-Ti-B coatings exhibited a dense and X-ray amorphous microstructure. It was demonstrated that the chemical composition and mechanical properties of Al-Mg-Ti-B coatings were significantly altered by applying different negative bias voltages during the HIPIMS process. The XPS results showed that oxygen concentration in the coatings was reduced from ~ 22 at.% to ~ 8 at.% and the number of oxygen-boron bonds dropped with an increasing bias voltage, which contributed significantly to the improved mechanical properties. Nano-indentation results showed that the nano-hardness and elastic modulus of the HIPIMS Al-Mg-Ti-B coatings were as high as 37 GPa and 348 GPa, respectively.