2004 Volume 45 Issue 5 Pages 1731-1737
The creep behavior of NiAl-9Mo eutectic alloy has been studied in an effort to understand the characteristic that the alloy exhibits of the low stress exponent of 4.75 and the high apparent activation energy of 410 kJ/mol during the steady-state creep of under the test conditions. The material exhibits threshold behavior with a threshold stress of 17.9 MPa. TEM observation reveals that the creep deformation is mainly governed by dislocation climb in NiAl matrix phase. Large recoverable strain is observed after unloading under the transient creep and increases with the increase of stress or temperature. It exhibits an activation energy 232 kJ/mol, suggesting the processes is controlled by the flow behavior of the matrix phase. The apparent creep activation energy under constant stress is a combination of the creep flow activation energy of the matrix and the activation energy for the damage process at the phase interface.