Molecular dynamic method was used to investigate the diffusion behavior of helium atom in the LaNiAl alloy system. The results have shown that diffusion coefficient of helium atom increased as the temperature increased from 300 to 1500K, which indicates that helium atom gets more active via thermal desorption. The diffusion coefficient 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 increasing temperature. Compared with metallic La, Ni, Al and Pd, the simulation result implies 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 indicated the correlation between the diffusion behavior of helium atoms and capacity of materials for helium retention. Therefore, it could be considered to be a feasible method for evaluating the helium retention capacity of materials by determining the diffusion properties of interstitial helium atoms.

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