Papers by Author: André Schneider

Abstract: A Fe3Al based single phase alloy was rolled at 600 °C and 400 °C and the kinetics of recrystallisation in A2 and B2 phase regions was determined in conjunction with the kinetics of the A2-B2 ordering and recovery. At 700°C and 800°C the recrystallisation kinetics depends strongly on the temperature of rolling while at 900°C only a small influence is visible. These results are attributed to the high stored energy in the sample rolled at 400 °C and its high recovery rate at 900 °C, leading to a similar level in stored energy as for the sample rolled at 600 °C in the beginning of annealing. At lower temperatures, in contrast, the difference in stored energy is conserved over longer times in the annealing process. Almost half the apparent activation energy was observed in the ordered state compared to that in the disordered state.

Abstract: It has been shown in literature that the mechanical properties of Fe3Al base alloys are strongly dependent on the heat treatment subsequent to warm rolling. Therefore, the recrystallization behavior of 3 different hot and warm rolled and annealed Fe3Al-based alloys has been investigated. Two of these alloys contain different forms and amounts of second phase particles, while a pure binary alloy was taken as reference. All alloys develop a-(<110>||RD) and g-(<111>||ND) fiber bcc-type rolling and annealing textures, however, the amount of a- and g-fibers vary in dependence of the alloy composition. The current work presents the investigations on the nucleation process during annealing that has been studied by means of high resolution backscatter electron diffraction (EBSD) in the SEM. In particular the occurrence of orientation gradients in the deformed structure and their crystallographic relationship to the formation of new grains was investigated. It was shown, that small particles favor the a-fiber component by hindrance of the growth of new grains. In contrast, large particles lead to particle stimulated nucleation. This weakens the overall texture but does not randomize it since the orientation gradients around particles keep a relationship with the matrix orientation.