ELECTRON,ION AND PHOTON EMISSION FROM FRESH SURFACES OF METAL ACCOMPANYING DEFORMATION AND FRACTURE

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We examined the use of chemisorptive emission (electron emission accompanying the adsorption of a reactive gas on a metal surface) and atomic force microscopy as measures of plastic deformation during fracture along a metallic Mg/glass interface. Localized ductile deformation in the metallic phase enhances the fracture energy, exposes metallic Mg to the reactive O_2 atmosphere, and produces intense emission. The number of electrons emitted following fracture in low-pressure oxygen atmospheres is strongly correlated with the total energy expended during failure (peel energy). The presence of localized ductile deformation is verified by atomic force microscopy (AFM) : voids are observed on surfaces yielding significant emissions and enhanced fracture energies. These voids are not observed on samples yielding the lowest peel energies and emission intensities, i.e., where the contribution of deformation to the peel energy is negligible. The potential for chemisorptive electron emission (CS … More E) as a probe of deformation along interfaces involving Mg, Ti, and Al is promising.Electronic speckle pattem inteferometry (ESPI) has been applied to the measurement of deformation, strain, and thermal expansion during the cooling down and warming up processes between room temperature and low temperatures (minimum -20K). Samples are several commercial available metallic (SUS, Al, and Ti) and non-metallic (FRP, Alunina, Teflon, and SiO_2) materials. The ESPI method offers a non-contact and temperature-independent method to measure the displacement of materials subject to large temperature changes, as long as the correlations of the speckle patterns are kept. This metod presents an essential advantage over the conventional ones in that the information remains recorded on the video tape recorder for further analysis. The mechanical behavior of structural materials due to the thermal deformation are successfully measured during the cooling down or warming up processes, and applicability of ESPI methods to the low temperature engineering are experimentally confirmed. Less