Acta Metallurgica Sinica (English Letters) ›› 2011, Vol. 24 ›› Issue (3): 195-204.DOI: 10.11890/1006-7191-113-195

• 研究论文 • 上一篇    下一篇

Highe-strain-rate Superplasticity in Oxide Ceramics: a Trial of Mirostructural Design Based on Creep-cavitation Mechanisms

Keijiro Hiraga   

  1. Nano Ceramics Center,National National Institute for Materials Science,1-2-1, Sengen, Tsukuba-shi, Ibaraki 305-0047, Japan
  • 收稿日期:2010-12-01 修回日期:2011-05-04 出版日期:2011-06-25 发布日期:2011-06-13
  • 通讯作者: Keijiro Hiraga

High-strain-rate superplasticity in oxide ceramics: a trial of microstructural design based on creep-cavitation mechanisms

Keijiro HIRAGA, Byung-Nam KIM, Koji MORITA, Hidehiro YOSHIDA, Yoshio SAKKA, Masaaki TABUCHI   

  1. National Institute for Materials Science,1-2-1, Sengen, Tsukuba-shi, Ibaraki 305-0047, Japan
  • Received:2010-12-01 Revised:2011-05-04 Online:2011-06-25 Published:2011-06-13
  • Contact: Keijiro HIRAGA

Abstract: From existing knowledge about high-temperature cavitation mechanisms, necessary conditions were discussed for the suppression of cavitation failure during superplastic deformation in ceramic materials. The discussion, where special attention was placed on the relaxation of stress concentrations during grain-boundary sliding and cavity nucleation and growth, leaded to a conclusion that cavitation failure could be retarded by the simultaneous controlling of the initial grain size, the number of residual defects, diffusivity, dynamic grain growth and the homogeneity of microstructure. On the basis of this conclusion, high-strain-rate superplasticity (defined as superplasticity at a strain rate higher than 0.01 s-1  could be intentionally attained in some oxide ceramic materials. This was shown in tetragonal zirconia and composites consisting of zirconia, α-alumina and a spinel phase.

Key words: Grain-boundary sliding, Accommodation, Stress concentration, Diffusional relaxation, Cavity nucleation, Cavity growth, Dynamic grain growth