Eect of cavitation on superplastic ¯ow of 10% zirconia-dispersed alumina Byung-Nam Kim a * , Keijiro Hiraga a , Yoshio Sakka a , and Byung-Koog Jang b a Mechanical Properties Division, National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan b National Institute for Advanced Interdisciplinary Research, 1-1-4 Higashi, Tsukuba, Ibaraki 305-8562, Japan Received 20 December 2000; accepted 27 February 2001 Keywords: Mechanical properties; Ceramics; Theory and modeling Introduction In most superplastic materials, concurrent cavitation occurs during high-temperature deformation. The size and volume of cavity increases exponentially with increasing tensile strain [1], and failure occurs by interlinkage of the cavities. Cavitation also in- ¯uences the deformation behavior of a material by lowering ¯ow stress. The eective stress within the material is intensi®ed by the reduction of the eective load-bearing) cross-sectional area caused by cavitation. The strain softening which is generally ob- served in stress±strain curves during superplastic deformation, is mainly due to cavi- tation. In the present study, we examine the eect of cavitation on ¯ow stress in Al 2 O 3 dispersed with 10 vol% ZrO 2 . Creep parameters are evaluated by considering dynamic grain growth during deformation, and ideal ¯ow stress for the case of non-cavitation is also predicted. The dependence of ¯ow stress on cavitation is examined and compared with some theoretical and empirical relations proposed. Additionally, we propose a simple model on stress intensi®cation, which takes the shape eect of cavity into ac- count. Scripta Materialia 45 2001) 61±67 www.elsevier.com/locate/scriptamat * Corresponding author. Tel.: +81-298-59-2539; fax: +81-298-59-2501. E-mail address: kim@nrim.go.jp B.-N. Kim). 1359-6462/01/$ - see front matter Ó 2001 Acta Materialia Inc. Elsevier Science Ltd. All rights reserved. PII:S1359-646201)00992-7