Molecular dynamics was used to investigate the diffusion behavior of helium atoms in the LaNiAl alloy system (table 16). The results showed that the diffusion coefficient of the helium atom increased as the temperature was increased from 300 to 1500K, which indicated that helium atom became more active via thermal desorption. The diffusion coefficients in LaNi5 and LaNi4Al were about 1.5 x 10−5 and 1.1 x 10−6cm2/s at 1300K, respectively, and the diffusion barrier of He were 1.45 and 0.52eV, respectively. The helium diffusion was shown to be enhanced with temperature increasing. Compared with metallic La, Ni, Al and Pd, the simulation result implied that helium atom was more stable and difficult to diffuse in LaNi5 and LaNi4Al alloys, which were the most promising materials for helium retention in experiments. The results reflected the correlation between diffusion behavior of helium atoms and the capacity of materials for helium retention. Therefore, it could be considered as a feasible method to evaluate the helium retention capacity of materials via determining the diffusion properties of interstitial helium atom.

Helium Diffusion Behavior and Its Retention in LaNiAl Alloy from Molecular Dynamic Simulations. Wang, L., Hu, W., Deng, H.: Nuclear Instruments and Methods in Physics Research B, 2011, 269[14], 1689-92