Chen Ru-Cheng(陈汝承) a) , Yang Li(杨 莉) ab) † , Dai Yun-Ya(代云雅) a) , Zhu Zi-Qiang(朱自强) a) , Peng Shu-Ming(彭述明) c) , Long Xing-Gui(龙兴贵) c) , Gao Fei(高 飞) b) † , and Zu Xiao-Tao(祖小涛) a)

The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr(Fe, Cr) 2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr(Fe, Cr) 2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr(Fe, Cr) 2 . The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.

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We develop an isotropic empirical potential for molecular hydrogen (H2) and deuterium (D2) by fitting to solidstate data, which is appropriate for classical molecular dynamics (CMD) approach. Based on the prior isotropic intermolecular potential used in self-consistent phonon approximation, a zero-point energy term and an embedded energy term are introduced to describe the H2–H2 and D2–D2 interactions in CMD simulations. The structure, cohesive energy and elastic properties of solid H2 (D2) are used as the fitting database. The present method is tested by calculating the melting point of solid H2, and the pressure and bulk elastic modulus as a function of volume. The developed potentials well reproduce many properties of solid H2 and D2.