Microstructure formation mechanism of Mo2C/W2C/Mo2C three-layer film on Mo substrate prepared by magnetron sputtering and carburization

This work presents a new concept for preparing ceramic multilayers: carburization of refractory metal multi- layers. Unlike the direct deposition of ceramic multilayers, we prepared a Mo/W multilayer film on a Mo substrate using magnetron sputtering and then carburized the sample to obtain a Mo2C/W2C ceramic multilayer film. The simplest ceramic three-layer film is the main research object of this work. Our study shows that, during the carburization, the carbide layers grew inward with two ceramic/metal carburization frontiers, with the Mo2C/Mo frontier leading the W2C/W frontier. W2C can grow epitaxially on the Mo2C grains without nucleation, forming columnar grains of half Mo2C and half W2C across the interlayer interface. The ceramic three-layer film was nonporous, and there was a significant interdiffusion of Mo and W elements at the interlayer interfaces, and the final film-substrate interface was the Mo2C/Mo interface located inside the initial Mo substrate. The hardness of the ceramic film with a thickness of 5.5-7.5 mu m was about 1500-1600 HV. The peeling of the outermost Mo2C layer started at 42 N, and the peeling of the W2C layer occurred at 90 N, but the inner Mo2C layer was not peeled at 90 N.