Diffusion calculations with two atomic models in h.c.p Zr-Nb diluted alloys

V. P. RAMUNNI; A. M. F. RIVAS

Roma

Congreso; 3rd Global Congress & Expo on Materials Science & Engineering-GCEMSE-2018, ROMA.; 2018

p { margin-bottom: 0.1in; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Liberation Serif", "Times New Roman", serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback"; font-size: 12pt; }p.ctl { font-family: "FreeSans"; font-size: 12pt; }In this work we perform a comparison of atomic diffusionmulti-frequency models for h.c.p. lattices. Specifically, in dilutedh.c.p. Zr-Nb alloy, we calculate, the tracer self- and impuritydiffusion coefficients, with Ghate´s eight frequencies model [1] andwith the 13 frequencies model recently developed by Allnatt etal. [2]. For the latter we investigate the tight-binding limitand the 5-frequency limit of the model. Our exhaustive calculations have been performed using, for bothmodels, classical molecular static techniques (MS), as well as,quantum ab-initio calculations within both LDA and GGAapproximations. Our ab-initio calculations show that a, so called,5-frequency model, without pairs dissociation nor anisotropy in thejump frequencies, that only needs three frequencies, is sufficientto obtain solvent and solute anisotropic diffusion coefficients thatare in agreement with experimental data. keyword:Diffusion, modeling, numerical calculations, vacancy mechanism,diluted Alloys, h.c.p. Zr-Nb.Bibliography[1]P. Ghate, Phys. Rev. 133, A1167 (1964).[2]A. R. Allnatt, I. V. Belova and G. E. Murch, Phil. Mag. 94:22,2487-2504 (2014).