Transformational Plasticity in Bi2O3

Transformational plasticity associated with the monoclinic-to-cubic phase transition at 730°C in Bi2O3 was observed and characterized. This phenomenon is explained in terms of Greenwood and Johnson's model of internal stress-induced deformation, proceeding, in this instance, by a time-dependent, grain-size-sensitive creep mechanism, probably grain-boundary sliding. Criteria are proposed for choosing other prospective transformationally plastic ceramics; they are met by Bi2WO6, which also exhibits extensive transformation plasticity.