Phase growth patterns for Al2O3/GdAlO3 eutectics over wide ranges of compositions and solidification rates
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2021年第6期
论文作者：Weidan Ma Jun Zhang Haijun Su Guangrao Fan Min Guo Lin Liu Hengzhi Fu
摘 要：Phase selection and growth characteristics of directionally solidified Al2 O3/GdAlO3（GAP） faceted eutectic ce ramics are investigated over wide ranges of compositions and solidification rates to explore the eutectic coupled zone.Through the obse rvation of the quenched solid-liquid interface,the competitive growth of primary faceted Al2 O3 phase,prima ry non-faceted GAP phase and Al2 O3/GAP eutectic with diffe rent morphologies is detected.Microstructure transitions from wholly eutectic to primary Al2 O3（GAP） dendrite plus eutectic and then to wholly eutectic are found in Al2 O3-2 O mol% Gd2 O3 hypoeutectic（Al2 O3-26 mol%Gd2 O3 hypereutectic） ceramics with the increase of solidification rate.The dendrite growth of faceted Al2 O3 and non-faceted GAP phases are well predicted by KGT model,which have introduced appro p riate dimensionless supersaturation Ω 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 Al2 O3/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 Al2 O3/GAP eutectic ceramics is studied.
Weidan Ma，Jun Zhang，Haijun Su，Guangrao Fan，Min Guo，Lin Liu，Hengzhi Fu
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University
摘 要：Phase selection and growth characteristics of directionally solidified Al2 O3/GdAlO3（GAP） faceted eutectic ce ramics are investigated over wide ranges of compositions and solidification rates to explore the eutectic coupled zone.Through the obse rvation of the quenched solid-liquid interface,the competitive growth of primary faceted Al2 O3 phase,prima ry non-faceted GAP phase and Al2 O3/GAP eutectic with diffe rent morphologies is detected.Microstructure transitions from wholly eutectic to primary Al2 O3（GAP） dendrite plus eutectic and then to wholly eutectic are found in Al2 O3-2 O mol% Gd2 O3 hypoeutectic（Al2 O3-26 mol%Gd2 O3 hypereutectic） ceramics with the increase of solidification rate.The dendrite growth of faceted Al2 O3 and non-faceted GAP phases are well predicted by KGT model,which have introduced appro p riate dimensionless supersaturation Ω 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 Al2 O3/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 Al2 O3/GAP eutectic ceramics is studied.
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