No abstract

We employed a recently developed semi-empirical Zr potential to determine the diffusivities in the hcp and bcc Zr via molecular dynamics simulation. The point defect concentration was determined directly from MD simulation rather than from theoretical methods using T=0 calculations. We found that the diffusion proceeds via the interstitial mechanism in the hcp Zr and both the vacancy and interstitial mechanisms give contribution in diffusivity in the bcc Zr. The agreement with the experimental data is excellent for the hcp Zr and for the bcc Zr it is rather good at high temperatures but there is a considerable disagreement at low temperatures.

No abstract

An improved diffusion model of pore annihilation during hot isostatic pressing of single crystals of nickel-base superalloys is proposed. The model considers dissolution of pores by emission of vacancies and their diffusion sink to low-angle boundaries. The calculation, which takes into account pore size distribution, predicts the kinetics of pore annihilation similar to experimental one.