Solute drag effects during the dynamic recrystallization of nickel

Solute drag effects during dynamic recrystallization were studied using five different nickel-sulfur alloys. The steady stale stress for dynamic recrystallization, measured using hot compression tests, depends on the sulfur concentration. The experimental results are analyzed using a model that relates the steady state stress to the grain boundary mobility. At the lower temperatures, the mobilities are strongly reduced by a solute drag effect; above a transition temperature, the drag effect becomes negligible. The extent of sulfur segregation at grain boundaries during recrystallization was assessed using cryogenic tensile tests of microsamples removed from the hot compressed specimens. The fracture surfaces exhibit the characteristics of intergranular brittleness when hot compression is carried out within the "grain boundary segregation" temperature range; above the transition temperature, the fracture surfaces are purely ductile. (C) 1999 Acta Metallurgica me. Published by Elsevier Science Ltd. All rights reserved.