Anisotropic grain growth based on the atomic adsorption model in WC-25 pct Co alloy

Abstract

The process of triangular prism formation and abnormal grain growth of WC was modeled using pseudo-Monte-Carlo simulation based on atomic adsorption and the coalescence mechanism. Grains of WC evolved into a triangular prism shape due to {1010} and {1210} planes of fast growth rate. Coalescence of {1010} and {1100} planes subsequent to the anisotropic evolution was the main reason for the abnormal grain growth. The probability of coalescence computed by the Monte-Carlo method agreed well with a theoretical prediction. Experimental evaluation of the computational model was made in sintered WC-25 wt pct Co alloy. The experimental alloy was made with WC powder of different particle size, 0.8 m and Ϫ325 mesh, respectively, and with two different sintering conditions: solid-phase sintering and liquid-phase sintering. The sample made from the coarse powder (Ϫ325 mesh) showed the same morphological characteristics as those of the original milled state, whereas the sample made from the fine powder (0.8 m) assumed a triangular prism shape quickly during solid-phase sintering. The anisotropic growth process of the latter sample could be explained by using the adsorption and coalescence model.

Review: liquid phase sintering

“…• Ryoo et al [189] used a pseudo-MC simulation based on atomic adsorption and coalescence to model the process of triangular prism formation and abnormal grain growth of WC-25Co during LPS.…”

Consolidation Techniques

“…A variety of approaches are under investigation. For example, Ryoo, Hwang, Kim, and Chung (2000) detailed the use of the Monte Carlo method to track anisotropic grain growth in WC-Co. Unfortunately, most of the simulations are 2D and inherently flawed when compared to 3D microstructures.…”