采用三维有限元方法计算了不同形状因子的γ强化相在基体为γ相的Ni基高温合金中引起的弹性应变能密度,进而建立了以形状因子为变量的弹性应变能密度表达式。通过最小化γ′强化相引起的弹性应变能和界面能之和,得到了γ′强化相的平衡形状与其特征半径之间的函数关系。本文的分析很好地解释了文献报道的Ni基高温合金中γ′强化相形状演变的实验规律,结果表明:通过三维有限元法结合强化相粒子形状近似法计算模型,可以给出复杂情况下强化相粒子引起的弹性应变能密度的表达式,并有效地应用于材料共格相变的热力学研究。
The expression for elastic energy due to coherent precipitates plays an important role in the thermodynamic calculation of phase transformations in precipitation strengthening materials for which elastic energy must be considered. However, in most cases, it was quite difficult to obtain analytic expressions for elastic strain energy in materials with anisotropic and/or inhomogeneous elasticity. The three- dimensional finite element method was a suitable straight forward technique in obtaining the expressions for elastic energy in materials with anisotropic and inhomogeneous elasticity. When the elastic energy due to coherent precipitates with different values of shape parameters were obtained by the finite element method, the approximate expression for the elastic energy can be conveniently established by means of data-fitting. As an example,the shape transitions of coherent γ′ precipitates from a sphere to a cube observed in Ni-base superalloys with γ matrix were investigated. The equilibrium shape of the γ′ precipitates was obtained by minimizing the sum of the elastic strain energy and interface energy. The calculation results are in good agreement with the theoretical and experimental data available.
参考文献
[1] | Voorhees P W;McFadden G B;Johnson W C .On the morphological development of second-phase particles in elastically-stressed solids[J].Acta Metallurgica Et Materialia,1992,40(11):2979-2992. |
[2] | Fujii T;Tamura T;Kato M et al.Size-dependent equilibrium shape of Co-Cr particles in Cu[J].Microscopy and Microanalysis,2002,8:1434-1435. |
[3] | Maheshwari A;Ardell AJ .Morphological evolution of coherent misfitting precipitates in anisotropic elastic media[J].Physical Review Letters,1993,70(15):2305-2308. |
[4] | Susnmu Onaka;Noriko Kobayashi;Toshiyuki Fujii .Simplified energy analysis on the equilibrium shape of coherent gamma' precipitates in gamma matrix with a superspherical shape approximation[J].Intermetallics,2002(4):343-346. |
[5] | CahnJ W;Larche F .A simple model for coherent equilibrium[J].Acta Metallurgica,1984,32(11):1915-1923. |
[6] | LeeJ K;Tao W .Coherent phase equilibria:Effect of composition-dependent elastic strain[J].Acta Metallurgica Et Materialia,1994,42(02):569-577. |
[7] | Chen, S.;Li, C.;Du, Z.;Guo, C.;Niu, C..Overall composition dependences of coherent equilibria[J].Calphad: Computer Coupling of Phase Diagrams and Thermochemistry,2012:65-71. |
[8] | M. FAEHRMANN;P. FRATZL;O. PARIS;E. FAEHRMANN;WILLIAM C. JOHNSON .INFLUENCE OF COHERENCY STRESS ON MICROSTRUCTURAL EVOLUTION IN MODEL Ni-Al-Mo ALLOYS[J].Acta Metallurgica et Materialia,1995(3):1007-1022. |
[9] | Kindrachuk V;Wanderka N;BanhartJ .Y' / 'Y "co-precipitation in Inconel 706 alloy:A 3 D finite element study[J].Materials Science and Engineering A:Structural Materials Properties Microstructure and Processing,2006,417(1-2):82-89. |
[10] | MacSleyneJ;Uchic M D;SimmonsJ P et al.Three-dimensional analysis of secondary 'Y' precipitates in Rene-88 DT and UMF-20 superalloys[J].Acta Materialia,2009,57(20):6251-6267. |
[11] | J.S. Van Sluytman;T.M. Pollock .Optimal precipitate shapes in nickel-base y-y' alloys[J].Acta materialia,2012(4):1771-1783. |
[12] | Mura T.Micromechanics of Defects in Solids[M].Martinus Nijhoff,Dordrecht,1987 |
[13] | Susumu Onaka;Noriko Kobayashi;Toshiyuki Fujii .Energy analysis with a superspherical shape approximation on the spherical to cubical shape transitions of coherent precipitates in cubic materials[J].Materials Science & Engineering, A. Structural Materials: Properties, Misrostructure and Processing,2003(1/2):42-49. |
[14] | Susumu Onaka .Averaged Eshelby tensor and elastic strain energy of a superspherical inclusion with uniform eigenstrains[J].Philosophical Magazine Letters,2001(4):265-272. |
[15] | Jaklic A;Leonardis A;Solina F .Computational Imaging and Vision[J].Kluwer Academic Dordrecht,2000,20:13-39. |
[16] | Toshiyuki Fujii;Susumu Onaka;Masaharu Kato .Shape-dependent strain energy of an inhomogeneous coherent inclusion with general tetragonal misfit strains[J].Scripta materialia,1996(10):1529-1535. |
[17] | Bacon DJ;Barnett D M;Scattergood R O .Anisotropic continuum theory of lattice defects[J].Progress in Materials Science,1979,23:51-262. |
[18] | Karma A B;Ardell AJ;Wagner C NJ .Lattice misfits in four binary Ni-base 'Y/'Y' alloys at ambient and elevated temperatures[J].Metallurgical and Materials Transactions A:Physical Metallurgy and Materials Science,1996,27(10):2888-2896. |
[19] | FRANK R.N. NABARRO .Rafting in Superalloys[J].Metallurgical and Materials Transactions, A. Physical Metallurgy and Materials Science,1996(3):513-530. |
- 下载量()
- 访问量()
- 您的评分:
-
10%
-
20%
-
30%
-
40%
-
50%