STRAIN-INDUCED BRAIN BOUNDARY MIGRATION IN BORON-DOPED NI76AL24

Nickel aluminide containing 24 at.-%Al and doped with 0.2 at.-%B was c old rolled to 40% and annealed at 835 degrees C for 1 h to develop gra in boundary bulges. The positions of the bulges were monitored as a fu nction of time during isothermal annealing at 835, 850, 875, 900, and 848 degrees C. The initial migration rate increased with increasing te mperature. However, the displacement of the bulge increased with a dec reasing rate at all temperatures. This was attributed to simultaneous recovery of the strained regions of the material during the boundary m igration. Analysis of the results showed that the experimental data ag reed well with the developed equations. The activation energy for reco very 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.