Studie lokalizace cyklické plastické deformace pomocí FIB techniky

Study of cyclic strain localization and fatigue crack initiation using FIB technique

článek v časopise - ostatní, Jost

en

Focused ion beam (FIB) technique together with other advanced microscopic techniques was applied to study the early microstructural changes leading to fatigue crack initiation in cyclically strained polycrystals (nickel, 316L steel). Dislocation structures of persistent slip bands (PSBs) and surrounding matrix were investigated in detail using electron channeling contrast imaging (ECCI) technique (concurrently in the FIB cross-section and on the specimen surface) and simultaneously with the surface relief topography using transmission electron microscopy (TEM) of thin surface foils prepared by in situ lift-out technique. True shape of extrusions and intrusions and the path of initiated fatigue cracks were assessed in three dimensions by FIB micro-tomography. The role of twin boundary in cyclic strain localization and fatigue crack initiation is discussed. Principal advantages and some limitations of FIB technique in fatigue crack initiation studies in polycrystals are highlighted.

Technika fokusovaného iontového svazku (FIB) spolu s dalšimi pokročilými technikami byla použita při studiu změn v mikrostruktuře vedoucích k iniciaci únavových trhlin oceli 316L. Dislokační struktury perzistetních skluzových pásu a okolní matrice byly pozorovány pomocí metody ECCI a zároven pozorováním folie v transmisním mikroskopu připravené z perzistetntního pásu pomocí techniky FIB. Skutečný tvar extruze a intruze and tvar iniciuící trhliny byl odhalen pomocí FIB mikrotomografie. Role dvojčatové hranice je diskutována.

Focused ion beam (FIB) technique together with other advanced microscopic techniques was applied to study the early microstructural changes leading to fatigue crack initiation in cyclically strained polycrystals (nickel, 316L steel). Dislocation structures of persistent slip bands (PSBs) and surrounding matrix were investigated in detail using electron channeling contrast imaging (ECCI) technique (concurrently in the FIB cross-section and on the specimen surface) and simultaneously with the surface relief topography using transmission electron microscopy (TEM) of thin surface foils prepared by in situ lift-out technique. True shape of extrusions and intrusions and the path of initiated fatigue cracks were assessed in three dimensions by FIB micro-tomography. The role of twin boundary in cyclic strain localization and fatigue crack initiation is discussed. Principal advantages and some limitations of FIB technique in fatigue crack initiation studies in polycrystals are highlighted.

Iniciace únavové trhliny, perzistentní skluzový pás, extruze, intruze, niklová austenitická ocel, fokusovaný iontový svazek

Fatigue crack initiation, Persistent slip band (PSB), Extrusion, Intrusion, Nickel Austenitic steel, Focused ion beam (FIB)

2012

01.02.2012

0142-1123

39

1

44–53

8