Observations on the Zirconium Hydride Precipitation and Distribution in Zircaloy-4

Abstract

Hydride precipitation and distribution in hot-rolled and annealed Zircaloy-4 plate samples artificially induced by gaseous hydrogen charging were studied primarily by neutron tomography, scanning electron microscopy (SEM), and SEM-based electron backscattered diffraction techniques. The precipitated hydride platelet (δ-ZrH1.66) at a hydrogen pressure of 20 atm was found following the {111}δ-ZrH1.66//(0001) α-Zr with the surrounding α-Zr matrix. The microstructural characterization indicated that hydrides with a relatively uniform distribution were precipitated on the rolling-transverse section of the plate, whereas, on the normaltransverse section, a hydride concentration gradient was present with a dense hydride layer near the surface. Further, the neutron tomography investigations clearly identified the nonuniform spatial distribution of hydrides. Thin hydride layers preferentially formed on the sample surface, and the concentrated hydrides precipitating at the edges/corner of the sample were observed. The causes for the localized hydride accumulation were also discussed. Disciplines Engineering | Science and Technology Studies Publication DetailsWang, Z., Garbe, U., Li, H., Harrison, R. P., Kaestner, A. & Lehmann, E. (2014 Hydride precipitation and distribution in hot-rolled and annealed Zircaloy-4 plate samples artificially induced by gaseous hydrogen charging were studied primarily by neutron tomography, scanning electron microscopy (SEM), and SEM-based electron backscattered diffraction techniques. The precipitated hydride platelet (d-ZrH 1.66 ) at a hydrogen pressure of 20 atm was found following the {111} d-ZrH1.66 //(0001) a-Zr with the surrounding a-Zr matrix. The microstructural characterization indicated that hydrides with a relatively uniform distribution were precipitated on the rolling-transverse section of the plate, whereas, on the normal-transverse section, a hydride concentration gradient was present with a dense hydride layer near the surface. Further, the neutron tomography investigations clearly identified the nonuniform spatial distribution of hydrides. Thin hydride layers preferentially formed on the sample surface, and the concentrated hydrides precipitating at the edges/ corner of the sample were observed. The causes for the localized hydride accumulation were also discussed.

IDENTIFIKASI BAHAN KELONGSONG PADUAN ZrNbMoGe HASIL UJI HIDRIDASI 400ï‚°C - 1 JAM MENGGUNAKAN TEKNIK DIFRAKSI = IDENTIFICATION ON ZrNbMoGe ALLOY OF 400ï‚°C-1 HOUR HYDRIDATION TEST FOR CLADDING MATERIALS BY USING DIFFRACTION TECHNIQUE

“…Knowledge of hydrogen concentration is needed when assessing the response of zirconium alloys to hydrogen. The hydrogen concentration is critical to the tests; too much hydrogen may cause hydrides to be present at the peak temperature reached before the lower test temperature is attained, while too little hydrogen may provide insufficient hydrogen for hydride precipitation during testing and give a false, low crack velocity 3) .…”

Quantitative analysis of hydrogen uptake, diffusion and distribution in nuclear fuel rod claddings made of zirconium alloys

“…The strong difference between the total neutron cross sections of hydrogen and zirconium provides the possibility of ex-and in-situ investigations of this system by means of neutron imaging [1][2][3][4][5][6][7][8]. The dependence of the total macroscopic neutron cross section on the hydrogen concentration can be determined by means of calibration specimens with known hydrogen concentration.…”

H2 PERMEATION BEHAVIOR OF Cr2AlC AND Ti2AlC MAX PHASE COATED ZIRCALOY-4 BY NEUTRON RADIOGRAPHY

“…Hydrogen uptake in zirconium alloy can be studied quantitatively by means of neutron imaging as shown by various groups [5][6][7][8]. First neutron radiography investigations of the hydrogen permeability through Ti 2 AlC and Cr 2 AlC MAX phase coatings on Zry-4 are described in this paper.…”