Depth profile of oxide volume fractions of Zircaloy-2 in high-temperature steam: An in-situ synchrotron radiation study

Abstract

a b s t r a c tTo study the steam oxidation behavior of Zircaloy-2, a high-energy synchrotron X-ray diffraction technique was applied to perform an in-situ oxidation measurement. The depth profiles of oxide volume fractions were obtained at both 600 and 800°C. Multiple layers, including ZrO 2 scale, (a + b) Zr matrix with ZrO 2 incursions, and (a + b) Zr matrix, were mapped according to the volume fraction of each phase. The volume fractions of these phases were observed to change gradually with different distances to the surface, without a sharp edge distinguishing each of the layers. The ZrO 2 consisted of tetragonal and monoclinic crystal structures, which were observed to coexist with different ratios of volume fractions in depth. The higher amount of tetragonal ZrO 2 observed in the very inner region of the oxidizing Zircaloy sample indicates that the tetragonal crystal structure is the ab initio phase type, in which new oxide molecules form at the metal-oxide interface.

In situ synchrotron tensile investigations on 14YWT, MA957, and 9-Cr ODS alloys

“…showed the highest tensile strength and fracture toughness, and the lowest fracture toughness transition temperature in both irradiated and unirradiated conditions [15]. High-energy synchrotron X-ray has been extensively used to characterize microstructural development during in-situ mechanical or thermal tests for a variety of materials [17][18][19][20][21][22][23][24][25][26][27][28].…”

Sample environment for in situ synchrotron corrosion studies of materials in extreme environments

“…Corrosion of zirconium alloy fuel cladding in water or steam and the associated hydrogen pickup is a limiting factor for increasing fuel burn-up in current and future reactors. [1][2][3][4][5][6][7][8][9][10][11][12] The hydrogen pickup associated with the corrosion process can embrittle the cladding by hydride formation. The corrosion of zirconium alloys occurs at the metal/oxide interface.…”

“…20 High synchrotron X-ray energy and brightness, coupled with advanced sample environments, present an exceptional opportunity to understand the fundamental interfacial processes involved in the degradation of materials in extreme environments. 3,6,11,12 In our work, we demonstrate the capabilities of an in situ sample environment that we developed to monitor oxidation at zirconium alloy-steam interfaces under corrosive conditions using in situ synchrotron X-ray diffraction (XRD). The in situ sample environment provides the capability of precisely controlling the temperature during oxidation using a LabVIEW-based platform.…”