13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- the specimens elongation. For each loading step, the loading frame containing the specimen was removed from the testing machine, at fixed values of deformation. The specimens, under load condition, was analyzed by means of: 1) a light optical microscope, characterized by a wide observation field; all the investigated specimen length was observed in order to identify the crack initiation site. The investigated steps are eng = 0%, 5%, 10%, and 14% (failure); 2) a diffractometer in order to evaluate XRD spectra. XRD measurements were made with a Philips X-PERT diffractometer equipped with a vertical Bragg–Brentano powder goniometer. A step–scan mode was used in the 2θ range from 40° to 90° with a step width of 0.02° and a counting time of 2 s per step. The employed radiation was monochromated CuKα (40 kV – 40 mA). The calculation of theoretical diffractograms and the generation of structure models were performed using the PowderCell software [8]. The investigated steps are at eng = 0% and 5%. a) b) Figure 1. Tensile equipment: a) loading frame, b) tensile machine. a) b) Figure 2. Etched surface: a) etched-deformed and observed, b) deformed, cleaned and re-etched. Specimen Loading Frame Loading Frame LVDT Step Motor
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