Microstructure, Mechanical Properties and first Principles Calculations of Mo/VC Multilayers

Abstract

In the present work, Mo/VC multilayers with constant period (10 nm) and different modulation ratios (from 6:4 to 9:1) were deposited by dc magnetron sputtering. We investigated the microstructure and mechanical properties of Mo/VC multilayers. XRD and TEM results indicated that Mo was a bcc structure and VC was a NaCl B1 (fcc) structure. An HRTEM image revealed the coherent interfaces between the Mo and VC layers. Hardness and toughness were studied using the Nanoindent and Microindent methods, respectively. It was found that the multilayers hardness remained as high as ~22 GPa, while the toughness increased from 2.91 to 4.70 MPa·m1/2 and the modulation ratio varied from 6:4 to 9:1. The enhancement of both hardness and toughness is attributed to the interfaces and the lamellated structure. The first-principles method was also used to determine the most stable interface model and the formation mechanism of the interface between the Mo and VC layers.