Fractographic examinations of fracture in polycrystalline S2 ice

Fractographic examinations were carried out on the fracture surfaces of both single-edge notched bend (SENB) and wedge-loaded compact tension (WLCT) specimens of S2 freshwater ice. Formvar solutions provided an effective means of making replicas that revealed various patterns of the fracture surfaces. The fracture modes consisted of both cleavage and brittle intergranular fracture, with cleavage fracture dominating. The cleavage planes of the S2 ice were mainly the {0 0 0 1} and {10¯1 1} planes under the experimental conditions for this study. Kinks forming new grain boundaries were found on the fracture surfaces of polycrystalline S2 ice for the first time. Kinking is regarded as a possible mechanism of plastic deformation for polycrystalline ice and to partially account for the high fracture energy of S2 ice found in this study.