Effect of light elements impurity atoms on grain boundary diffusion in FCC metals: a molecular dynamics simulation

Effect of carbon and oxygen impurity atoms on diffusion along the tilt grain boundaries with <100> and <111> misorientation axis in metals with FCC lattice was studied by mean of molecular dynamics method. Ni, Ag, and Al were considered as metals. Interactions of metal atoms with each other were described by many-particle Clery-Rosato potentials constructed within the framework of tight binding model. To describe interactions of atoms of light elements impurities with metal atoms and atoms of impurities with each other, Morse pair potentials were used. According to obtained results, impurities in most cases lead to an increase in self-diffusion coefficient along the grain boundaries, which is caused by deformation of crystal lattice near the impurity atoms. Therefore, additional distortions and free volume are formed along the boundaries. It is more expressed for carbon impurities. Moreover, with an increase in concentration of carbon in the metal, an increase in coefficient of grain-boundary self-diffusion was observed first, and then a decrease followed. This behavior is explained by formation of aggregates of carbon atoms at grain boundary, which leads to partial blocking of the boundary. Oxygen atoms had smaller effect on diffusion along the grain boundaries, which is apparently explained by absence of a tendency to form aggregates and lesser deformation of crystal lattice around impurity. The greatest effect of impurities on self-diffusion along the grain boundaries among the examined metals was observed for nickel. Nickel has the smallest lattice parameter, impurity atoms deform its lattice around itself more than aluminum and silver, and therefore they create relatively more lattice distortions in it and additional free volume along the grain boundaries, which lead to an increase in diffusion permeability. Diffusion coefficients along the high-angle boundaries with misorientation angle of 30° turned out to be approximately two times higher than along low-angle boundaries with a misorientation angle of 7°. Diffusion along the <100> grain boundaries flowed more intensively than along the <111> boundaries.

molecular dynamics, metal, impurity, grain boundary, tilt boundary, diffusion

1. Veiga R.G.A., Goldenstein H., Perez M., Becquart C.S. Monte Carlo and molecular dynamics simulations of screw dislocation locking by Cottrell atmospheres in low carbon Fe–C alloys. Scripta Materialia. 2015, vol. 108, pp. 19–22.

2. Kar’kina L.E., Kar’kin I.N., Yakovleva I.L., Zubkova T.A. Computer simulation of carbon diffusion near b/2[010](001) dislocation in cementite. Physics of Metals and Metallography. 2013, vol. 114, no. 2, pp. 155–161.

3. Atrens A. Dependence of the pinning point dislocation interaction energy on the dislocation structure in zirconium oxygen alloys. Scripta Metallurgica. 1974, vol. 8, no. 4, pp. 401–412.

4. Sursaeva V., Zieba P. Diffusion impurity drag of twin grain boundaries and triple junctions motion in zinc. Defect and Diffusion Forum. 2005, vol. 237-240, pp. 578–583.

5. Iwasaki T., Sasaki N., Yasukawa A., Chiba N. Molecular dynamics study of impurity effects on grain boundary grooving. Japan Society of Mechanical Engineers. Part A. 1997, vol. 40, no. 1, pp. 15–22.

6. Goldschmidt H.J. Interstitial Alloys. London: Butterworths, 1967, 640 p.

7. Pauling L. The Nature of the Chemical Bond. 3 rd ed. Ithaca: Cornell University Press, 1960, 664 p.

8. Cleri F., Rosato V.V. Tight-binding potentials for transition metals and alloys. Physical Review B. 1993, vol. 48, pp. 22−33.

9. Zorya I.V., Poletaev G.M., Starostenkov M.D. Impurity atoms of light elements in metal crystals: molecular dynamics simulation. Fundamental’nye problemy sovremennogo materialovedeniya. 2018, vol. 15, no. 4, pp. 526–532. (In Russ.).

10. Poletaev G.M., Starostenkov M.D. Mutual diffusion at the interface in a two-dimensional Ni-Al system. Technical Physics Letters. 2003, vol. 29, no. 6, pp. 454–455.

11. Rakitin R.Yu., Poletaev G.M., Aksenov M.S., Starostenkov M.D. Mechanisms of grain-boundary diffusion in two-dimensional metals. Technical Physics Letters. 2005, vol. 31. no. 8, pp. 650–652.

12. Poletaev G.M., Starostenkov M.D. Dynamic collective displacements of atoms in metals and their role in the vacancy mechanism of diffusion. Physics of the Solid State. 2009, vol. 51, no. 4, pp. 727–732.

13. Ruda M., Farkas D., Garcia G. Atomistic simulations in the Fe–C system. Computational Materials Science. 2009, vol. 45, pp. 550–560.

14. Vashishta P., Kalia R.K., Nakano A., Rino J.P. Interaction potentials for alumina and molecular dynamics simulations of amorphous and liquid alumina. Journal of Applied Physics. 2008, vol. 103, no. 8, pp. 083504.

15. Palumbo G., Aust K.T. A coincident axial direction (CAD) approach to the structure of triple junctions in polycrystalline materials. Scripta Metallurgica et Materialia. 1990, vol. 24, pp. 1771–1776.

16. Ovid’ko I.A., Sheinerman A.G. Diffusion percolation along triple junctions in nanocrystalline materials. Reviews on Advanced Materials Science. 2004, vol. 6, no. 1, pp. 41–47.

17. Zhou Y., Erb U., Aust K.T., Palumbo G. The effects of triple junctions and grain boundaries on hardness and Young’s modulus in nanostructured Ni–P. Scripta Materialia. 2003, vol. 49, no. 1, pp. 825–830.

18. Prokoshkina D., Esin V.A., Wilde G., Divinski S.V. Grain boundary width, energy and self-diffusion in nickel: Effect of material purity. Acta Materialia. 2013, vol. 61, no. 14, pp. 5188–5197.

19. Poletaev G.M., Zorya I.V., Starostenkov M.D., Rakitin R.Yu., Tabakov P.Ya. Molecular dynamics simulation of the migration of tilt grain boundaries in Ni and Ni 3 Al. Journal of Experimental and Theoretical Physics. 2019, vol. 128, no. 1, pp. 88–93.

20. Yue-Lin L., Shuo J., Ying Zh. Interaction between impurity nitrogen and tungsten: a first-principles investigation. Chinese Physics B. 2012, vol. 21, no. 1, pp. 016105.

21. Amara H., Roussel J.-M., Bichara C., Gaspard J.-P., Ducastelle F. Tight-binding potential for atomistic simulations of carbon interacting with transition metals: Application to the Ni-C system. Physical Review B. 2009, vol. 79, no. 1, pp. 014109.

22. Siegel D.J., Hamilton J.C. First-principles study of the solubility, diffusion, and clustering of C in Ni. Physical Review B. 2003, vol. 68, pp. 094105.

23. Zhu Y.-A., Dai Y.-C., Chen D., Yuan W.-K. First-principles study of carbon diffusion in bulk nickel during the growth of fishbone-type carbon nanofibers. Carbon. 2007, vol. 45, no. 1, pp. 21–27.

24. Aguiar-Hualde J.M., Magnin Y., Amara H., Bichara C. Probing the role of carbon solubility in transition metal catalyzing single-walled carbon nanotubes growth. Carbon. 2017, vol. 120, pp. 226–232.

25. Lee B.-J. A modified embedded-atom method interatomic potential for the Fe–C system. Acta Materialia. 2006, vol. 54, no. 3, pp. 701–711.

26. Vykhodets V.B., Kurennykh T.E., Lakhtin A.S., Fishman A.Ya. Diffusion of light elements in BCC, FCC and HCP metals. Solid State Phenomena. 2008, vol. 138, pp. 119–132.