[en] Influence of cascade atoms on the preferential emission of isotopes during sputtering has been studied by a static Monte Carlo simulation program, for zero-fluence and low-energy (below 1 keV) Xe ion bombardment of a ⁶³Cu_0.5⁶⁵Cu_0.5 target. Calculations show that the probabilities of the sputtered cascade atoms of ⁶³Cu and ⁶⁵Cu are over 80%. The calculations also show that towards the surface, the momentum flux of the cascade atoms of ⁶³Cu is much more than that of ⁶⁵Cu. The momentum asymmetry in the collision cascade plays a dominating role in preferential emission of the lighter ⁶³Cu atoms in the near-normal direction during low-bombarding-energy ⁶³Cu-⁶⁵Cu sputtering

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[en] Dynamic Monte Carlo simulation is used to explore the B isotope sputtering during 1 keV Kr ion irradiation. It is found that at both zero and high fluences the light isotope is preferentially ejected in the near-normal direction; between them there is a low fluence (1.4 x 10¹⁵ ions/cm²), at which the isotope fractionation is independent of the emission angle in the nearly whole angular range

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[en] This work has applied the embedded atom method (EAM) to calculate concentration distribution of Mg, Ni and Al at a Ni₃Al-5 at.% Mg grain boundary, and the Mg-induced distortion energies at the grain boundary, the bulk and the free surface. The calculated concentration distributions show that Mg segregation is present with Al-depletion and Ni-enrichment at the grain boundary. The cause might be not only that at the same zone, the Mg-induced distortion energy in the site of Al is always negative and lower than that of Ni, but also that the Mg-induced distortion energy in the Al site at the grain boundary is the lowest among those at all zones

[en] Based on the Monte Carlo simulation conjoined with the embedded atom method (EAM) potentials, the double species model is established to study relaxation of impure Ni₃Al grain boundaries. The present double species model suggests that the impure atoms are not only segregating species but also inducing species. The present model also suggests that study of combination of the positive (the impure atoms induce Ni atoms to substitute into Al sites) and the negative (the impure atoms substitute into Ni sites) bulk effects of impure atoms is available, in order to understand dependence of the cohesion of the impure Ni₃Al grain boundary (or the Ni enrichment at the impure Ni₃Al grain boundary) on the bulk concentration of impure atoms. The double species model is clarified in comparison between the Ni₃Al-B and the Ni₃Al-Mg systems

[en] Mechanisms affecting multicomponent material sputtering are complex. Isotope sputtering is the simplest in the multicomponent materials sputtering. Although only mass effect plays a dominant role in the isotope sputtering, there is still an isotope puzzle in sputtering by ion bombardment. The major arguments are as follows: (1) At the zero fluence, is the isotope enrichment ejection-angle-independent or ejection-angle-dependent? (2) Is the isotope angular effect the primary or the secondary sputter effect? (3) How to understand the action of momentum asymmetry in collision cascade on the isotope sputtering?