Abstract
Nickel aluminide containing 24 at.-%AI and doped with 0.2 at.-%B was cold rolled to 40% and annealed at 835°C for 1 h to develop grain boundary bulges. The positions of the bulges were monitored as a function of time during isothermal annealing at 835, 850, 875, 900, and 848°C. The initial migration rate increased with increasing temperature. However, the displacement of the bulge increased with a decreasing rate at all temperatures. This was attributed to simultaneous recovery of the strained regions of the material during the boundary migration. Analysis of the results showed that the experimental data agreed well with the developed equations. The activation energy for recovery was 463 kJ mol-1 compared with the activation energy of 317 kJ mol-1 for boundary migration. These values were consistent with the model.
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