Work hardening in ionic crystals

Abstract

The work-hardening characteristics of two ionic materials with different structures and slip systems, CaF₂ and NaCl, are studied and compared. It is found that the work hardening is similar in both, and athermal in origin. Stage I work hardening is due to interactions with blocking obstacles and forest dislocations, and the bowing out at the sessile jogs formed by multiple cross glide. The latter is the principal contribution except at low strain-rates or high temperatures. Stage II work hardening is due to interactions with blocking obstacles, forest dislocations and the debris formed on planes inclined to the principal slip planes. An important contribution is provided by one or both of the last two.