Dynamic Recrystallization (DRX) as the Mechanism for Sn Whisker Development. Part I: A Model

A model is proposed that attributes whisker growth in metals and alloys to dynamic recrystallization (DRX) and, in particular, DRX at the material surface. Each step in the DRX process was correlated to the development of whiskers. The DRX model depends upon the details of the deformation process(es) responsible for new grain initiation and growth. The dependencies exhibited by DRX as a function of deformation strain rate, temperature, and microstructure correlate with the behaviors of whisker development. Anomalous or ultrafast diffusion mechanisms, either by themselves or associated with the deformation structures, provide the means of mass transport necessary to grow whiskers. In Part II of this study, the strain and rate kinetics data are determined for Sn. Parts I and II, together, provide a critical step towards developing a capability to predict the conditions that are likely to cause whisker growth in engineering applications.