Study of C diffusion in WC/W boundaries using Adaptive Kinetic Monte Carlo

• Wear of WC/Co tools during turning of Ti-alloys is a big concern within the tooling industry. The wear is mainly attributed chemical wear in the form of diffusion/dissolution of tool material in the material of the workpiece. The reasons for these processes being so pronounced are in large part due to the low thermal conductivity of Ti which results in very high cutting zone temperatures. Experimental investigations have shown that a layer of BCC W forms on the outermost WC grains in contact with the workpiece. The process by which this layer forms must be through the diffusion of C away from the tool as W is only present in the contact in the form of tool material. The rate of this C diffusion is of importance in understanding the atomic scale processes responsible for the observed wear. In this work Kinetic Monte-Carlo is used to estimate the diffusion rate of C in WC/W interfaces and gain an understanding of the diffusion behaviour within these systems at timescales beyond previous computational investigations. The results show that C diffusion is restricted to the interface region and that it follows the paths set by the bottom surface of the BCC W, within the [10$\bar{1}$0]-I/[100] interface the estimated overall diffusion rate has a barrier of $\Delta E=1.24\pm 0.2$ eV and a pre-factor of $D_0=1.6\times10^{-8} \pm 3.8\times10^{-8}$ m$^{2}$/s estimated from calculations of the Mean Square Displacement at temperatures of 1173 K, 1073 K, 973 K and 873 K.

Ämnesord

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

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