25 KB161 KB20 KB199219991998Derder, C.Grabke, Hans JürgenHennesen, K.Lindemann, JanineViefhaus, Helmutletnik:32številka:6str. 475-480ISSN:1318-0010COBISSID:91050URN:URN:NBN:SI:doc-J42IHQDSenInštitut za kovinske materiale in tehnologijeŽelezarna JeseniceŽelezarna RavneŽelezarna ŠtoreKovine zlitine tehnologijedifuzijajeklalezenjemikrostrukturasegregacijazlitineEffects of impurities in Alloy 800 on the grain boundary diffusion and high temperature creep| Vpliv nečistoč v zlitin 800 na difuzijo po mejah zrn in na visoko temperaturno lezenje|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 processRaziskali smo difuzijo, segregacije in lezenje, da bi ugotovili vpliv nečistoč na mikrostrukturo, lastnosti lezenja in samodifuzijo v različnih industrijskih Alloy 800 in v laboratorijsko izdelanih Alloy 800 z dodtakom P in S. Difuzija ?$^{59}Fe$? v osnovnem materialu in po mejah zrn v Alloy 800 je bila izmerjena z metodo radioaktivnih preiskav presekov, v temperaturnem področju od 800 do 1000°C. Za zlitino Alloy 800 H je aktivacijska energija difuzije ?$^{59}Fe$? po mejah zrn (209 ?$\pm$?17) kJ/mol. Uporaba Suzuouka aproksimacije je bila potrjena z autoradiogrami. Raztopljeni elementi, posebno P zvišajo aktivacijsko energijo difuzije Fe po mejah zrn s tem, da segregirajo na mejah zrn in zvišajo precipitacijo karbidov na mejah zrn. Isti material staran 100 ur na 800°C je bil uporabaljen za eksperimente lezenja pod konstantno obremenitvijo in pri konstantni temperaturi. Kemijska sestava jamic, nastalih pri lezenju in mej zrn je bila določena s Spektroskopijo na Augerjeve elektrone (AES). Pri zlitini 800 z 0,09 mas% P je bila izmerjena na mejah zrn obogativev s 14 at.% P. Nobene povezave med difuzijo in tvorbo jamic pri lezenju ni bilo mogoče najti. Dodatek P jasno poveča odpornost Zlitine 800 pri protilezenju; kar lahko razložimo s fosfidi v zrnih in s povečano precipitacijo ?$Cr_{23}C_6$? na mejah zrn med procesom lezenjaNadaljuje se kot: Materiali in tehnologijeTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije