Effect of Initial Oriented Columnar Grains on the Texture Evolution and Magnetostriction in Fe–Ga Rolled Sheets

Abstract

Abstract:The effects of initial oriented columnar grains on the texture evolution and magnetostriction in (Fe 83 Ga 17 ) 99.9 (NbC) 0.1 rolled sheets were investigated. The recrystallization texture evolution exhibited the heredity of initial orientations, concerning the formation of cube and Goss textures in the primary recrystallized sheet for the columnar-grained sample. Moreover, the growth advantage of Goss grains was more obvious than that of cube grains during the secondary recrystallization process. Because of the combined effect of this and Nb-rich precipitates as inhibitors, a sharp Goss texture and very large Goss grains were achieved in the secondary recrystallized sheet for the columnar-grained sample. For comparison, the secondary recrystallization in the equiaxed-grained sample was not fully developed although there were Nb-rich precipitates as inhibitors. We think this could be ascribed to the large particle size and premature coarsening of precipitates. Magnetostriction of the secondary recrystallized columnar-grained sheet was up to 232 ppm owing to the ideal Goss texture and quite large grain size. As for the equiaxed-grained sample, the magnetostriction was only 163 ppm in the secondary recrystallized sheet.

Secondary Recrystallization Goss Texture Development in a Binary Fe81Ga19 Sheet Induced by Inherent Grain Boundary Mobility

“…While {112}-{111}<110> is the stronger texture at subsurface layer, {111}<112> and {113}<361> are the orientation density peaks at central layer. This primary recrystallization texture is different from the usual observation in grain-oriented silicon steels and Fe-Ga sheets, with strong {111}<112> and weak Goss at the subsurface layer [17][18][19]24,25]. Figure 2 illustrates the microstructure and texture of warm rolled sheets.…”

“…The annealing temperature range and heating rate must be also controlled to make full use of the coherent difference in grain boundary mobility for the AGG of Goss grains in binary Fe-Ga alloy [18,23]. At the temperature range of 950-1000 • C, Goss grains can grow rapidly by virtue of the large fraction of HEGBs (Figure 8), where the AGG of Goss grains generally appears in Fe-Ga alloy [18][19][20][21]23]. Abnormal Goss grains rapidly annex the matrix grains and island grains at the temperature of 1000-1025 • C (Figures 8a and 9a) [38].…”

“…Abnormal Goss grains rapidly annex the matrix grains and island grains at the temperature of 1000-1025 • C (Figures 8a and 9a) [38]. A suitable heating rate can effectively maintain the difference in grain boundary mobility to ensure the development of secondary recrystallization [18][19][20].…”

“…Micron-sized particles of NbC are added in an Fe-Ga alloy sheet to suppress the growth of primary grains, and on this basis, the abnormal grain growth (AGG) of Goss grains is achieved by the surface energy effect from sulfur alloying or H 2 S atmosphere. Na et al [16,17] reported that nearly single-crystal Goss grains with magnetostriction coefficient of 300 ppm were developed in Fe 81 Ga 19 sheets by combining 1-2.5 mol.% NbC micron particles with an H 2 S + Ar atmosphere. Yuan and Liu et al [18][19][20] obtained centimeters-sized Goss grains with a magnetostriction coefficient of 245 ppm at annealing atmosphere containing the sulfur element in Fe-Ga-based sheet added 0.1 mol.% NbC.…”

“…Na et al [16,17] reported that nearly single-crystal Goss grains with magnetostriction coefficient of 300 ppm were developed in Fe 81 Ga 19 sheets by combining 1-2.5 mol.% NbC micron particles with an H 2 S + Ar atmosphere. Yuan and Liu et al [18][19][20] obtained centimeters-sized Goss grains with a magnetostriction coefficient of 245 ppm at annealing atmosphere containing the sulfur element in Fe-Ga-based sheet added 0.1 mol.% NbC. Recently, magnetostriction coefficient of 285 ppm and secondary recrystallization Goss grains were induced by the dispersedly precipitated nanometer-sized sulfides and the well-matched pinning effect by the given primary recrystallization texture characteristic in Fe-Ga thin sheets [21].…”