Molecular dynamics simulation of the effect of dislocations on the martensitic transformations in a two-dimensional model

J. A. Baimova,M. P. Kashchenko,S. V. Dmitriev,V. G. Pushin,R. I. Babicheva,D. V. Gunderov

doi:10.22226/2410-3535-2017-4-442-446

Abstract

MD simulation of direct and reverse MT in the framework of the 2D model of an ordered alloy shows that dislocations can be considered as the nucleation centers of martensite during direct MT. In the absence of dislocations, martensite nucleates homogeneously at lower temperatures. The reverse MT occurs in the presence of twinned martensite and domain walls in the system, which means that even in the absence of dislocations, the structure of the alloy is not ideal. During the reverse MT, the perfect dislocations split into partial dislocations. It should be noted that for selected model parameters MT is associated with large lattices deformations, therefore, temperature hysteresis is also large, which is not typical for SM alloys. However, the consideration of the Acta Mater. 95, 37 (2015). effects of SM and superelasticity is not prohibited in frame of 14. C. Ni, H. Ding, XJ.. Jin. J. Alloys Compd. 546, 1 (2013). this model, since the degree of coherence of the martensite 15. S. Kazanc, FA. . Celik, S. Ozgen. J. Phys. Chem. Solids. 74, and austenite lattices is quite high. One of the important 1836 (2013). problems for futher investigations is the studying of the MT 16. T. Suzuki, M. Shimno, K. Otsuka, X. Ren, A. Saxena. as the detonation process [36]. J. Alloys Compd. 577S, S113 (2013). 17. B. Wang, E. Sak-Saracino, N. Gunkelmann, Aknowledgements. S.V. D. acknowledges support from the H.M. Urbassek. Comp. Mater. Sci. 82, 399 (2014). Russian Foundation for Basic Research, grant No. 16-58-48001 18. C. Tatar, S. Kazanc. Current Applied Physics. 12, 98 IND_omi (design of the research, discussion of the results). (2012). J.A. B and V.G. P. are grateful for the financial support from 19. A.R. Kuznetsov, Yu.N. Gornostyrev, M.I. Katsnelson, the Russian Science Foundation, grant No. 15-12-10014 A. V. Trefilov. Mater. Sci Eng. A309–311068 (2001). (numerical simulations and writing the paper). R.I. B. thanks 20. I.N. Kar’kin, Yu.N. Gornostyrev, L.E. Kar’kina. Phys. financial support from the Russian Science Foundation, grant Solid State. 52, 431 (2010). No. 17-79-10410 (numerical simulations). The work of D. V. G. 21. Y. N. Gornostyrev, IN. . Kar’kin, LE. . Kar’kina. Phys. Solid was supported by the Saint-Petersburg State University, State. 53, 1388 (2011). research grant No. 6.65.43.2017 (discussion of the results). 22. J.A. Baimova, R.I. Babicheva, A.V. Lukyanov, V.G. Pushin,

Highlights

Martensitic transformation (MT) is a cooperative effect, which indicates the existence of a governing process
It should be noted that the inequality KMS > KAS reflects the presence of wide overlapping temperature ranges for the realization of direct and reverse MT, which can be explained by large values of the elastic strain related with MT
molecular dynamics (MD) simulation of direct and reverse MT in the framework of the 2D model of an ordered alloy shows that dislocations can be considered as the nucleation centers of martensite during direct MT

Summary

Introduction

Martensitic transformation (MT) is a cooperative effect, which indicates the existence of a governing process. MT has the features of the phase transition of the first order, presence of which is determined by the deviation of the starting temperature of MT, ТMS, from the temperature of phase equilibrium, Т0. For a large deviation of ТMS from Т0, the description of all the peculiarities of MT is presented in the frames of the heterogeneous nucleation and controlling wave process. For small deviations of TMS from T0, MT is close to phase transitions of the second order, and coexistence of heterogeneous and homogeneous nucleation processes is possible. Using the ideas about the role of DNC and controlling wave process in calculating the morphological features of MT in alloys with SM effect [9, 10], including specific twinning variants [11], leads to good agreement with the experiment. The simplest version is to analyze the formation of transformation twins, while it is desirable to compare cases of homogeneous and heterogeneous nucleation

Objectives

Results

Conclusion