Autonomous filling of creep cavities in Fe-Au alloys studied by synchrotron X-ray nano-tomography. (December 2016)

• Record Type: Journal Article
• Authors: Fang, H.; Versteylen, C.D.; Zhang, S.; Yang, Y.; Cloetens, P.; Ngan-Tillard, D.; Brück, E.; van der Zwaag, S.; van Dijk, N.H.
• Is Part Of: Acta materialia. Volume 121(2016)
• Page Start: 352
• Page End: 364
• Publication Date: 2016-12
• Subjects: Self healing -- Creep -- Fe alloys -- Synchrotron radiation -- X-ray tomography; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2016.09.023
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The autonomous filling of creep-loading induced grain-boundary cavities by gold-rich precipitates at a temperature of 550 °C has been studied as a function of the applied load for Fe-Au alloys using synchrotron X-ray nano-tomography. The alloy serves as a model alloy for future self-healing creep resistant steels. The size, shape and spatial distribution of cavities and precipitates are analyzed quantitatively in 3D at a nanometer resolution scale. The filling ratios for individual cavities are determined and thus a map of the filling ratio evolution is obtained. It is found that the gold-rich precipitates only form at cavity surfaces and thereby repair the creep cavity. The shape of the cavities changes from equiaxed to planar crack like morphologies as the cavities grow. The time evolution of the filling ratio is explained by a simple model considering isolated cavities as well as linked cavities. The model predictions are in good agreement with the measurements. Graphical abstract: