Influence of substrate bias and temperature on the microstructure and mechanical properties of AlCrSiWN composite coatings prepared by chromizing-nitriding-magnetron sputtering hybrid process

In this study, AlCrSiWN composite coatings were deposited on AISI 316L stainless steel using a hybrid process combining chromizing, nitriding, and magnetron sputtering. The influence of substrate temperature (400 °C, 450 °C, 500 °C) and bias voltage (−50 V, −120 V, −170 V) on the microstructure and mechanical properties was systematically investigated. The results show that both parameters strongly interact. The optimal conditions are 450 °C and −120 V to −170 V, yielding a dense, defect-free coating with a uniform columnar structure and sharp interface with the chromized-nitrided diffusion layer. At 450 °C, the highest hardness reaches 39.0 GPa and adhesion exceeds 30 N. Lower temperatures limit densification, while higher temperatures cause grain coarsening and thermal softening. XRD reveals that all coatings exhibit a predominantly face-centered cubic (FCC) solid-solution structure. XPS analysis, with binding energies calibrated by the Fermi edge, confirms the presence of metal–nitride bonds, indicating the formation of a multicomponent (Cr,Al,Si,W)N solid solution. TEM/SAED confirms the presence of a minor amorphous Si–N phase. The designed multilayer architecture is also confirmed. This work provides essential experimental evidence and theoretical guidance for developing high-performance coatings with promising mechanical properties for potential applications.