M. Tacikowski et al., THE EFFECT OF CARBON AND SULFUR ON THE CHARACTER OF THE GRAIN-BOUNDARY POPULATION IN ALPHA-IRON, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 205(1-2), 1996, pp. 133-138
The grain boundary misorientations and CSL frequencies of a population
of about 250 boundaries in ultra high purity alpha-iron doped with sm
all quantities of carbon and sulphur have been determined by a SEM mic
rodiffraction BKD (Backscattered Kikuchi Diffraction) technique. The a
im is to examine the effect of these elements on the character of the
grain boundary population (CGBP). Samples containing about 75 wt, ppm
of sulphur and/or 150 (200) wt. ppm carbon were recrystallized at 725
degrees C after cold hydrostatic extrusion to epsilon = 1.1 It was fou
nd that the addition of sulphur and carbon modifies the CGBP of alpha-
iron. Sulphur clearly increases the density of low angle grain boundar
ies (LANGB), but only in the pure Fe-S binary alloy. The fractions of
the LANGB and coincidence site lattice grain boundaries (CSLGB) in the
Fe-C-S alloy are rather similar to those of Fe-C and thus the CGBP co
uld be controlled by carbon. As a consequence, the lowest fraction of
high energy random grain boundaries (RANGB) appears in the Fe-S alloy
at about two-thirds of the total population. The effect of carbon and
sulphur on the CGBP is interpreted in terms of grain boundary selectio
n as a consequence of an impurity-specific dragging effect or a precip
itation pinning effect on the migration of boundaries during recrystal
lization and subsequent grain growth.