The influence of varied modulation ratios on crystallization and mechanical properties of nanoscale TiB2/Al2O3 multilayers

Abstract

TiB2/Al2O3 multilayers with constant modulation periods and various modulation ratios ranging from 1:1 to 11:1 were synthesized on silicon wafer substrates by magnetron sputtering system. The amorphous structures of the TiB2/Al2O3 multilayers were characterized. The effect of modulation ratio on the microstructure and mechanical properties of the multilayers was investigated. The results revealed that crystallization of amorphous sublayer, performance of hardness, elastic modulus and residual stress of the multilayers largely depended on variations of modulation ratios. The hardness and elastic modulus of TiB2/Al2O3 multilayers were up to the maximum value (30.6 GPa and 460.1 GPa) at modulation ratio of 7:1. Moreover, the practical adhesion had been also remarkably improved. Further analysis suggested that crystallization of amorphous sublayer (individual layer) was the primary cause for mechanical performance improvement of the multilayers. This work proved that the modulation ratio was a key role in controlling the growth orientation of crystals of nanoscale TiB2/Al2O3 multilayers at room temperature.