Void formation in electron-irradiated Ni-12 at.% Ti alloys with modulated structures

Abstract

The void formation and swelling behaviour of a Ni-12 at.% Ti alloy has been studied by means of in situ electron-irradiation experiments in a high-voltage electron microscope. The alloy specimens were aged for various times at 873 K to produce different wavelenghs of the modulated structure and then irradiated with 0·5 MeV electrons at a temperature of 873 K. For the solution-treated and quenched specimen, void swelling is relatively large, and begins to decrease with increasing wavelength of the modulated structure. A minimum in swelling is found to occur at an intermediate wavelength of approximately 30 nm, corresponding to the maximum hardness state of the alloy. Coarsening of the modulated structure leads to a slight increase in the swelling.

The characteristic swelling behaviour of the alloy is interpreted in terms of the different climb efficiencies of edge dislocations in different wavelengths of the modulated structures.