Microstructure analysis of Al2O3/Er3Al5O12/ZrO2 DSECs prepared using high-frequency zone melting method

• Published in: Journal of alloys and compounds Vol. 830; p. 154653
• Main Authors: Wang, Shunheng, Liu, Juncheng
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.07.2020; Elsevier BV
• Subjects: Al2O3/Er3Al5O12/ZrO2 eutectic ceramic; Aluminum oxide; Directional solidification; Eutectics; Induction melting; Kinetic undercooling; Liquid-solid interfaces; Melting entropy; Microcracks; Microstructure; Process parameters; Rapid solidification; Solidification mechanism; Supercooling; Zirconium dioxide; Zone melting; Kinetic undercooling; Melting entropy; Solidification mechanism; Microstructure; Al2O3/Er3Al5O12/ZrO2 eutectic ceramic
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.154653

The microstructure of directionally solidified eutectic ceramics (DSECs) is mainly determined by the eutectic growth mode, properties of each phase, and solidification processing parameters. The Al2O3/Er3Al5O12(EAG)/ZrO2 DSECs were prepared using high-frequency induction melting, and their phase components, and microstructures were investigated. The results indicated that the samples were composed only of Al2O3, EAG, and ZrO2 phases. As an solidification rate increased from 5 to 500 mm/h, the microstructure was refined, and the distribution of the eutectic phases changed. This could be explained by the relationship between the undercooling, the growth rate and the melting entropy. The regular microstructure appeared in the samples prepared at low growth rate and it exhibited the form of triangles or squares. A polygonal colony structure was found in the DSECs obtained at 50 mm/h, which was related to the non-uniformed distribution of temperature fields near the solid-liquid interface. Furthermore, both of the internal microcrack and amorphous structure were identified in the rapidly solidified samples prepared at 500 mm/h. •Al2O3/EAG/ZrO2 DSECs were prepared via high-frequency induction zone melting.•There were two regularly arranged crystal phases, triangle or square, at a growth rate of 15 mm/h.•Colony structures was due to the non-uniform distribution of temperature.•High growth rate of 500 mm/h resulted in internal microcracks and amorphous structures.•The effect of the melting entropy on the growth of oxide eutectic was researched.