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  • Effects of impurities in Alloy 800 on the grain boundary diffusion and high temperature creep = Vpliv nečistoč v zlitini 800 na difuzijo po mejah zrn in na visoko temperaturno lezenje
    Lindemann, Janine ...
    Industrial Alloy 800 in different specifications and melts of Alloy 800 with addition od P and S were investigated using diffusion, segregation and creep measurements to reveal the influence of the ... impurities and to find relations between microstructures, creep properties and self-diffusivity. Using the radioactive tracer sectioning method the bulk and grain boundary diffusion of ▫$^{59}Fe$▫ was determined in Alloy 800 in the temperature range 800 to 1000°C. In Alloy 800H the activation energy of grain boundary diffusion of ▫$^{59}Fe$▫ is (209▫$\pm$▫17) kJ/mol. The use of the approximation of Suzuoka was confirmed by autoradiographs. Dissolved elements especially P increased the activation energy on the grain boundary diffusion of Fe by their segregation to the grain boundaries and by increasing carbide precipitation at the grain boundaries. The same materials - aged at 800°C for 100 h - were usedfor creep experiments under constant load and constant temperature. The chemical composition of the creep cavities and grain boundaries were analysed by Auger electron spectroscopy (AES). For Alloy 800 + 0.09 wt-% P an enrichment of about 14 at-% P was observed at the grain boundaries. No correlation of creep cavity formation and diffusivity could be found. The addition of P clearly enhances the creep strength of Alloy 800; this can be explained by phosphides in the grains and by enhanced precipitation of ▫$Cr_{23}C_6$▫ on the grain boundaries during the creep process.
    Vrsta gradiva - članek, sestavni del ; neleposlovje za odrasle
    Leto - 1998
    Jezik - angleški
    COBISS.SI-ID - 91050