Sintering behavior, microstructural evolution, and mechanical properties of ultra-fine grained alumina synthesized via in-situ spark plasma sintering

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• 作者：Kang Taek Lee^a ; ^{ktlee@dgist.ac.kr" class="auth_mail" title="E-mail the corresponding author} ; Seung Ii Cha^b ; Kyung Tae Kim^c ; Kyung Ho Lee^d ; Soon Hyung Hong^d ; ^{shhong@kaist.ac.kr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Alumina ; Amorphous ; Ultra-fine grain size ; Spark plasma sintering ; Abnormal grain growth
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：15 February 2016
• 年：2016
• 卷：42
• 期：3
• 页码：4290-4297
• 全文大小：2786 K

文摘

Ultra-fine grained Al₂O₃ was fabricated by in-situ spark plasma sintering (SPS) process directly from amorphous powders. During in-situ sintering, phase transformation from amorphous to stable α-phase was completed by 1100 °C. High relative density over 99% of in-situ sintered Al₂O₃ was obtained in the sintering condition of 1400 °C under 65 MPa pressure without holding time. The grain size of in-situ sintered Al₂O₃ body was much finer (~400 nm) than that of Al₂O₃ sintered from the crystalline α-Al₂O₃ powders. For in-situ sintered Al₂O₃ from amorphous powders, we observed a characteristic microstructural feature of highly elongated grains in the ultra-fine grained matrix due to abnormal grain growth. Moreover, the properties of abnormally grown grains were controllable. Fracture toughness of in-situ sintered Al₂O₃ with the elongated grains was significantly enhanced due to the self-reinforcing effect via the crack deflection and bridging phenomena.