Microscopic phase-field simulation of Cr atom substitution character during formation of Ll₂ and DO₂₂ phases in Ni-Cr-Al alloy

Abstract

The simulations of Cr atom substitution character during the formation of Ll₂ and DO₂₂ phases in Ni-Cr-Al alloy were performed at 873 K based on microscopic phase-field model. It is found that the substitution of Cr is affected by Cr and Al contents and limits of occupation probabilities of Cr atom in Ll₂ phase are present. The precipitate is single Ll₂ phase when the component is less than the limit, Cr atoms substitute the Al sublattices in Ll₂ phase, and both of atoms Al and Cr occupy the β-sites and complex phases Ni₃(Al_1−xCr_x) are formed; Cr atoms enter Ni sites when Al and Cr contents exceed the limit, and substitute β-sites or both of α-and β-sites. The DO₂₂ phase is formed at the boundary of Ll₂ phase.

Keywords

Ni-Cr-Al alloy / microscope phase-field / precipitation / substitution / simulation

References

[1] ChenL. Q., KhachaturyanA. G.. Computer simulation of decomposition reactions accompanied by a congruent ordering of the second kind [J]. Scripta Metall et Mater, 1991, 25(1): 61-66

[2] ChenL. Q., KhachaturyanA. G.. Computer simulation of structural transformations during precipitation of an ordered intermetallic phase [J]. Acta Metall Mater, 1991, 39(11): 2533-2551

[3] ChenL.-qing.. A computer simulation technique for spinodal decomposition and ordering in ternary systems [J]. Scripta Metall et Mater, 1993, 29(5): 683-688

[4] RaableD., XiangJ. Z.Computational materials science [M], 2002, Beijing, Chemistry Industry Press: 223-235

[5] KhachaturyanA. G.Theory of structural transformations in solids [M], 1983, New York, Wiley: 23-40

[6] PoduriR., ChenL. Q.. Computer simulation of atomic ordering and compositional clustering in the pseudobinary Ni₃Al-Ni₃V system [J]. Acta Mater, 1998, 46(3): 1719-1729

[7] ZhangJ. X., ChenL. Q.. Phase-field microelasticity theory and micromagnetic simulations of domain structures in giant magnetostrictive materials [J]. Acta Mater, 2005, 53(5): 2845-2855

[8] SeolD. J., HuS. Y., LiY. L., ShenJ., OhK. H., ChenL. Q.. Computer simulation of spinodal decomposition in constrained films [J]. Acta Mater, 2003, 51(10): 5173-5185

[9] LiuZ. H., LiuH., ZhangX. X., ZhangM., DaiX. F., HuH. F., ChenT. L., WuG. H.. Martensitic transformation and magnetic properties of Heusler alloy Ni-Fe-Ga ribbon [J]. Physics Letters A, 2004, 329(8): 214-220

[10] LuY.-l., ChenZ., LiY.-sheng.. Atomic-scale computer simulation for the coarsening mechanism of the cubic alloy including coherent strain energy [J]. Raremetal Materials and Engineering, 2006, 35(11): 1686-1690

[11] ZhaoY.-h., ZhangY., ChenZ.. Simulation for early precipitation process of Ni₇₅Al₄V₂₁ alloy by microscopic phase-field model [J]. Journal of Beijing University of Aeronautics and Astronautics, 2007, 33(8): 978-981

[12] CermakJ., GazdaA., RothovaV.. Interdiffusion in ternary Ni₃Al/Ni₃Al-X diffusion couples with X=Cr, Fe, Nb and Ti [J]. Intermetallics, 2003, 11(9): 939-946

[13] MekhrabovA. O., AkdenizM. V., ArerM. M.. Atomic ordering characteristics of Ni₃Al intermetallics with substitutional ternary additions [J]. Acta Mater, 1997, 45(3): 1077-1083

[14] OchiaiS., OyaY., SuzukiT.. Alloys behaviour of Ni₃Al, Ni₃Ga, Ni₃Si and Ni₃Ge [J]. Acta Mater, 1984, 32(2): 289-298

[15] MartyA., BessiereM., BleyF.. Determination of long range order in Ni-base ternary alloys by X-ray anomalous diffraction using synchrotron radiation [J]. Acta Matall Mater, 1990, 38(2): 345-350

[16] WuY. P., TsoN. C., SanchenJ. M.. Modeling of ternary site occupation in Ll₂ ordered intermetallics [J]. Acta Mater, 1989, 37(10): 2835-2840

[17] PareigeC., SoissonF., MartinG.. Ordering and phase separation in Ni-Cr-Al: Monte Carlo simulations vs three-dimensional atom probe [J]. Acta Mater, 1999, 47(6): 1889-1899

[18] DuvalS., ChambrlandS., CaronP., BlvetteD.. Phase composition and chemical order in the single crystal Nickel base siperalloy MC2 [J]. Acta Metall Mater, 1994, 42(1): 185-194

[19] ChuZ., ChenZ., WangY.-x., LuY.-li.. Microscopic phase-field simulation of atom substitution behavior in Ni-Cr-Al alloy [J]. Chinese Physics Letters, 2005, 22(8): 1841-1844

[20] BlavetteD., CadaeL., DeconihoutB.. The role of the atom probe in the study of nickel-based superalloys [J]. Materials Characterization, 2000, 44(1/2): 133-157