Caractérisation de la texture de recristallisation primaire et de la spécialité des joints de grains de tôles de Fe-3%Si par diffraction des electrons rétrodiffusés

Abstract

The EBSP (electron backscattering pattern) technique has been used to verify and to complete a study by Rouag [Th6se de Doctorat d'Etat (1988), Univ. de Paris Sud, Orsay, France] concerning the influence of crystallographic texture and grain boundaries during abnormal growth of Goss grains in Fe-3%Si sheets, grade Hi-B. 1000 individual orientations have been measured at three levels: at the surface, at a fifth of the thickness from the surface and at the middle of the sheet. This technique allows the calculation of a true orientation distribution function (ODF), which is not possible using X-ray (or neutron) diffraction. Indeed, for X-ray diffraction, only the even part of the ODF can be determined. For the even part of the ODF, the results obtained by EBSPs are in good agreement with those obtained by X-ray diffraction and show the importance of the contribution of the odd part (about 20% of the true ODF). Then the minimal value of the orientation number is determined to assess an ODF statistic. This short study shows that it is useful to determine a minimum of 1000 measurements at each level. From these 3000 measurements, the nature of the grain boundaries is determined showing a good agreement with results obtained in the literature. In particular, it appears that the percentage of coincidence site lattice (CSL) boundaries, which is about 10%, does not depend on the sampling position. Moreover, another short study of the influence of orientation number on the nature of grain boundaries shows that a good representation is obtained if about 750 measurements are taken into account.

High-Temperature Annealing Effect of Si in Group-V Ambient Prior to Heteroepitaxy of InAs in Metal–Organic Vapor Phase Epitaxy

“…The fraction of Goss grains is very weak (10 −1 %) [5,20], therefore it is unlikely that a Goss grain is among the near neighbours. [21].…”

Microtexture Characterization by EBSP in Iron and Titanium Alloys

“…Comparison between X ray diffraction and EBSP. amsurface, b---fifth, fifth of the sheet thickness from the surface and at the center, Rouag (1988), Penelle et al (1992), Baudin et al (1992).…”

“…(1988), Randle et al (1989), Rouag et al (1989), Penelle et al (1992). At a global scale, it is possible to calculate from a statistical point of view the respective percentages of special and general grain boundaries, Baudin et al (1992). This technique also allows one to solve the problem of the odd part F(g) and to calculate the total texture function F(g).…”

“…Finally, knowing the parameters of position, of orientation, of misorientation and of shape of the grains it will be possible to establish correlations between these different functions. However a first step consists in estimating the number of orientations required to obtain reliable results Wright et al (1990), Baudin et al (1992), especially concerning the O.D.F. calculation.…”

Determination of the total texture function from individual orientations modelled by a Lorentzian distribution

“…A first study has been made to compare the textures measured by X-ray diffraction and by electron 0021-8898/93/020207-07506.00 backscattering diffraction (Dingley, 1988) on three Fe-3%Si samples at the surface, at one fifth of the thickness from the surface and at the centre of a primary recrystallized sheet (Rouag, 1988;Penelle, Baudin, Paillard & Mora, 1991;Baudin, Paillard & Penelle, 1992). One fifth of the thickness was chosen because it has been shown that, during the final annealing of secondary recrystallization, which is performed in a hydrogen atmosphere, Goss grains expand in the subsurface between one fourth and one fifth of the sheet thickness from the surface.…”