Densification and grain growth kinetics of boron carbide powder during ultrahigh temperature spark plasma sintering
(1. Science and Technology on High Strength Structural Materials Laboratory, State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Zhejiang Libo Industrial Co., Ltd., Shaoxing 312000, China;
3. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;
4. Hunan Institute of Engineering, Xiangtan 411100, China)
2. Zhejiang Libo Industrial Co., Ltd., Shaoxing 312000, China;
3. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;
4. Hunan Institute of Engineering, Xiangtan 411100, China)
Abstract: Dense B4C material was fabricated using spark plasma sintering (SPS), and the densification mechanisms and grain growth kinetics were revealed. The density, hardness, transverse flexure strength and toughness of samples were investigated and the model predictions were confirmed by SEM and TEM experimental observations. Results show that SPSed B4C exhibits two sintering periods: a densification period (1800-2000 °C) and a grain growth period (2100-2200 °C). Based on steady-state creep model, densification proceeds by grain boundary sliding and then dislocation-climb-controlled mechanism. Grain growth mechanism is controlled by grain boundary diffusion at 2100 °C, and then governed by volume or liquid-phase diffusion at 2200 °C.
Key words: boron carbide; spark plasma sintering; densification mechanism; grain growth mechanism; grain boundary; diffusion