Phase growth patterns for Al2O3/GdAlO3 eutectics over wide ranges of compositions and solidification

• 作 者: Weidan Ma Jun Zhang Haijun Su Guangrao Fan Min Guo Lin Liu Hengzhi Fu
• 机 构: State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 7100
• 出 处: 材料科学技术（英文版）
• 发表日期: 2021年6期
• 关键词: Directional solidification Competitive growth Flexural strength Laser floating z

Phase selection and growth characteristics ofdirectionally solidified Al2O3/GdAlO3 (GAP) faceted eutectic ceramics are investigated over wide ranges of compositions and solidification rates to explore the eutectic coupled zone.Through the observation of the quenched solid-liquid interface,the competitive growth of primary faceted Al2O3 phase,primary non-faceted GAP phase and Al2O3/GAP eutectic with different morphologies is detected.Microstructure transitions from wholly eutectic to primary Al2O3 (GAP) dendrite plus eutectic and then to wholly eutectic are found in Al2O3-20 mol％ Gd2O3 hypoeutectic (Al2O3-26 mol％ Gd2O3 hypereutectic) ceramics with the increase of solidification rate.The dendrite growth of faceted Al2O3 and non-faceted GAP phases are well predicted by KGT model,which have introduced appropriate dimensionless supersaturation Ω2 to characterize the anisotropic growth of dendrites.Based on the maximum interface temperature criterion,the competitive growth of primary phase and eutectic is analyzed theoretically and the predicted coupled zone of Al2O3/GAP eutectic ceramics is in good agreement with the experimental results.Besides,the influence of microstructure with these different morphologies on the flexural strength of Al2O3/GAP eutectic ceramics is studied.