The effects of modulation period, modulation ratio, and deposition temperature on microstructure and mechanical properties of ZrB₂/W multilayers

Abstract

Monolithic ZrB₂, W coatings and ZrB₂/W multilayers with different modulation periods and modulation ratios were synthesized by ion beam assisted deposition at room temperature and 400°C. X-ray diffraction (XRD), scanning electron microscopy (SEM), surface profiler, and nanoindention were employed to investigate the influences of the deposition temperature and the modulation period on the growth, textures, interface structure, and mechanical properties of the multilayers. The results indicated that the multilayer with modulation period of 13 nm synthesized at room temperature possessed a higher hardness of 23.8 GPa. Deposition temperature gave a significant contribution to mechanical property enhancement. The 400°C-deposition temperature led to a maximum hardness and elastic modulus value of 32.1 and 399.1 GPa for ZrB₂/W multilayer with a modulation period of 6.7 nm. Its critical load increased to 42.8 mN and residual stress decreased to −0.7 GPa. A higher deposition temperature can cause an increase in interfacial atomic mixture and mobility of surface species, which induceds an increase in areal atomic density and dislocation pinning. These results as well as small nanoscale grain sizes should be related to hardness increase.