Strain induced premelting at grain boundaries and deformation bands in copper bulk bicrystals

Cracks were formed along grain boundaries and along deformation bands in th e interior of a grain in copper bulk bicrystals which had been compressed a t room temperature, and then annealed in a vacuum at 823 K without unloadin g. It is considered that the cracks along grain boundaries and deformation bands were formed by strain induced premelting; when localized regions with high dislocation density are formed close to grain boundaries or deformati on bands, the regions may melt at temperatures of approximately 0.5T(M) (T- M: the melting point in Kelvin). Premelting cracks along deformation bands were found for the first time in this study. It was found that the developm ent of premelting cracks was closely related to the duration of the compres sive load without a large drop during the heating process. Various experime ntal parameters which affect the formation and development of premelting cr acks are discussed.