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Application of focused ion beam (FIB) microscopy to the study of crack profiles
Author(s) -
Hong Wang,
Revie,
Phaneuf,
Qing Li
Publication year - 1999
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1046/j.1460-2695.1999.00159.x
Subject(s) - focused ion beam , materials science , scanning electron microscope , ion beam , microscopy , beam (structure) , grain boundary , composite material , optics , ion , microstructure , chemistry , physics , organic chemistry
Focused ion beam (FIB) microscopy is used to form an image similar to that formed in a conventional scanning electron microscope (SEM), but with greatly enhanced grain contrast due to the use of a primary ion beam as opposed to a beam of primary electrons as found in the SEM. In addition, by increasing the current of the positively charged gallium ion beam, it can be used as a precision, essentially stress‐free milling machine on a scale of tens of nanometres to several hundred microns. In this paper, the application of FIB microscopy to the study of crack profiles is reported. Samples of a Grade 448 (X‐65) pipeline steel were cyclically loaded in a dilute simulated groundwater solution of near neutral pH. Cracks that initiated on these samples were imaged in plan view and were locally cross‐sectioned using a high‐current focused gallium ion beam at different locations along the cracks. Samples were then tilted in situ to permit imaging of the crack profile, the grain structures around the crack tip and accurate measurement of the crack depth using the same ion beam at lower currents. The transgranular crack path and other microstructural features associated with crack development were clearly illustrated, and crack aspect ratio (depth/length) could be obtained. The capability of the FIB for enhanced imaging of grain structures, combined with its precision‐sectioning capability, make it a novel new tool for the study of cracks.