Počet záznamů: 1
Initiation of fatigue cracks in ultrafine-grained materials in highcycle fatigue region
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SYSNO ASEP 0434600 Druh ASEP C - Konferenční příspěvek (mezinárodní konf.) Zařazení RIV D - Článek ve sborníku Název Initiation of fatigue cracks in ultrafine-grained materials in highcycle fatigue region Tvůrce(i) Kunz, Ludvík (UFM-A) RID, ORCID
Fintová, S. (CZ)Celkový počet autorů 2 Zdroj.dok. XVII International Colloquium on Mechanical Fatigue of Metals (ICMFM17). - Amsterdam : Elsevier, 2014 / Gulagliano M. ; Vergani L. - ISSN 1877-7058 Rozsah stran s. 2-5 Poč.str. 4 s. Forma vydání Tištěná - P Akce ICMFM 2014 International Colloquium on Mechanical Fatigue of Metals /17./ Datum konání 25.06.2014-27.06.2014 Místo konání Verbania Země IT - Itálie Typ akce WRD Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova Cyclic slip bands ; Fatigue crack initiation ; Fatigue of ultrafine-grained materials ; Localization of cyclic platicity ; Point defects Vědní obor RIV JL - Únava materiálu a lomová mechanika Institucionální podpora UFM-A - RVO:68081723 UT WOS 000396733300001 EID SCOPUS 84904413149 DOI https://doi.org/10.1016/j.proeng.2014.06.213 Anotace Initiation of fatigue cracks in materials with conventional grain (CG) size was investigated very thoroughly in the past. There is an extensive knowledge on the localization of cyclic plasticity and early crack development; however, it cannot be straightforwardly applied to the ultrafine-grained (UFG) structures with the grain size below 1m, because the crack initiation mechanisms are related to dislocation structures, which cannot develop in UFG materials simply from the size reasons. The paper brings results of an experimental investigation of the cyclic strain localization and crack initiation by means of focused ion beam technique (FIB). Two substantially different materials as regards the crystallographic structure, namely UFG Cu and magnesium alloy AZ91 processed by equal channel angular pressing (ECAP) were investigated and the observed characteristic features of crack initiation were discussed. The observations bring evidence that in the high-cycle fatigue (HCF) region point defects generated by dislocation activity do play very important role in the fatigue crack initiation process in UFG Cu. Fatigue cracks initiate in slip bands which form in areas of near-by oriented grains and are characteristic by surface relief, consisting of extrusions and intrusions. Point defects and formation of cavities and voids along the active slip planes governs the HCF crack initiation. No grain coarsening and development of specific dislocation structure was observed in the regions of crack initiation in UFG Cu. The mechanism of the crack initiation in AZ91 alloy processed by ECAP was found to be similar to that known from CG alloy. The cracks initiate in cyclic slip bands which forms in individual grains due to their relatively large grain size. The initiated cracks propagate along the slip planes in a crystallographic way which corresponds to the quasicleavage mechanism often reported for CG Mg alloys. Pracoviště Ústav fyziky materiálu Kontakt Yvonna Šrámková, sramkova@ipm.cz, Tel.: 532 290 485 Rok sběru 2015
Počet záznamů: 1