Song Caiyu, Wang Shunheng, Liu Juncheng, Zhai Shuoyan
School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
School of Materials Science and Engineering, Shandong University of Technology, Zibo 255049, China.
Materials (Basel). 2018 Mar 30;11(4):534. doi: 10.3390/ma11040534.
Directionally solidified Al₂O₃/Er₃Al₅O (EAG) eutectic ceramic was prepared via vertical Bridgman method with high-frequency induction heating. The effects of the growth rate on the microstructure and mechanical properties of the solidified ceramic were investigated. The experimental results showed that there were no pores or amorphous phases in the directionally solidified Al₂O₃/EAG eutectic ceramic. Al₂O₃ phase was embedded in the EAG matrix phase, and the two phases were intertwined with each other to form a typical binary eutectic "hieroglyphic" structure. With the increase of growth rate, the phase size and spacing of the solidified Al₂O₃/EAG ceramic both decreased, and the growth rate and phase spacing satisfied the ² ≈ 60 formula of Jackson-Hunt theory. The cross section microstructure of the solidified ceramic always exhibited an irregular eutectic growth, while the longitudinal section microstructure presented a directional growth. The mechanical properties of the solidified ceramic gradually increased with the increase of growth rate, and the maximum hardness and fracture toughness could reach 21.57 GPa and 2.98 MPa·m respectively. It was considered that the crack deflection and branching could enhance the toughness of the solidified ceramic effectively.
采用高频感应加热的垂直布里奇曼法制备了定向凝固Al₂O₃/Er₃Al₅O（EAG）共晶陶瓷。研究了生长速率对凝固陶瓷微观结构和力学性能的影响。实验结果表明，定向凝固Al₂O₃/EAG共晶陶瓷中无气孔或非晶相。Al₂O₃相嵌入EAG基体相中，两相相互交织形成典型的二元共晶“象形文字”结构。随着生长速率的增加，凝固Al₂O₃/EAG陶瓷的相尺寸和间距均减小，生长速率与相间距满足杰克逊-亨特理论的²≈60公式。凝固陶瓷的横截面微观结构始终呈现不规则共晶生长，而纵截面微观结构呈现定向生长。凝固陶瓷的力学性能随着生长速率的增加而逐渐提高，最大硬度和断裂韧性分别可达21.57 GPa和2.98 MPa·m。认为裂纹偏转和分支可有效提高凝固陶瓷的韧性。
