Order - disorder transformation in Ni-V alloys under electron irradiation

The ordering transformations in nickel-rich Ni-V alloys were investigated in situ in a high voltage electron microscope in the temperature range from 300 K to 773 K. The progress of ordering/disordering was monitored from diffraction patterns taken after different periods of time. The {1 1/2 0} ordering instability was noticed during irradiation of ordered Ni3V alloy at 300 K. The increase/decrease in superlattice intensity corresponding to long range ordered phases (Ni3V and Ni2V) in Ni-29 at.% V alloy has been attributed to the net effect of the simultaneous operation of different competing processes such as radiation induced disordering, radiation induced ordering and thermal diffusion assisted ordering.