Grain growth in Zr-Fe thin films during in situ ion irradiation in a TEM

In situ ion-beam irradiation was used to study irradiation induced grain growth in co-sputter-deposited Zr/xFe (0% ≤ x ≤ 4.5%) nanocrystalline thin films. Samples were irradiated with 500 keV Kr ions to fluences in excess of 10¹⁶ ions/cm² (on the order of 80-100 dpa), at irradiation temperatures ranging from 20 K to 573 K. The average grain size increased monotonically with ion fluence until it reached a saturation value which depends both on temperature and on the presence of Fe. Similarly to thermal grain growth, the ion irradiation induced grain growth curves could be best fitted with curves of the type: Ln-L0n=KΦ. Grain growth at 20 K is similar to that which occurs at 298 K. Above 298 K, the rate of grain growth increases with irradiation temperature.