Mechanism for the multi-stage precipitation of Fe-Ni based alloy

doi:10.1016/j.jmst.2019.05.064

Abstract

Abstract:

This work lays great emphasis on the distribution evolution of sigma (σ) phase in Fe-Ni based N08028 alloy during aging process, the result of which could provide new insights into phase change and precipitation mechanism. It is found that the σ phase, in any case, tends to separate out with a granular shape at grain boundaries (GBs) primarily, and with the increment of time, it is obliged to precipitate in grain interiors (GIs) with a lamellar structure. The mechanisms for the evolving volume fraction and morphology of σ phase are discussed, and a model appropriate for the multi-stage behavior transforming from intergranular to intragranular precipitation is derived, as well as revealing the thermodynamics and transformation kinetics corresponding to this process. The results reveal that the occurrence of multi-stage precipitation is correlated with the redistribution of solute atoms and with the difference in coupling effect of thermodynamic driving force and kinetic activation energy between the intergranular and intragranular precipitation.

Key words: Precipitation, Intergranular precipitation, Intragranular precipitation, Thermodynamics, Transformation kinetics

Jiang Yan, Zuo Qiang, Liu Feng. Mechanism for the multi-stage precipitation of Fe-Ni based alloy[J]. J. Mater. Sci. Technol., 2019, 35(11): 2582-2590.

Figures/Tables 11

Fig. 1. XRD patterns obtained from specimen solution treated at 1200 °C for 2 h and aged at 900 °C for 16 h (a) and σ peaks obtained from specimens aged for various hours at (b) 1000 °C, (c) 950 °C and (d) 900 °C.

Fig. 2. OM photographs from specimens aged at temperatures of 1000 °C (a), 900 °C and 950 °C (b) for different times.

Fig. 3. SEM images of alloy after solution treatment (a) and the morphology of needle-like σ phases in GIs (b).

Fig. 4. Bright field TEM images of the precipitates at GBs (a) and in GIs (b) and HRTEM images of γ/σ interface locating at GBs (c) and GIs (d), with the electron diffraction pattern and enlarged view from the selected area.

Fig. 5. Schematic diagrams showing the diffusion process of intergranular precipitation (a) and the ellipse used to obtain the assumed morphology of intragranular precipitate (b).

Table 1 Equilibrium phases and corresponding compositions for alloy N08028 at different temperatures calculated with Thermo-calc and the calculated values of ΔGm and ΔGv.

Temperature (oC)	Phase	Fe (wt%)	Ni (wt%)	Cr (wt%)	Mn (wt%)	Mo (wt%)	ΔG_m (J/mol)	ΔG_v (J/m³)
900	γ	36.24	35.31	25.3	0.93	2.22	1313.44	3.19 × 10⁸
900	σ	29.12	14.4	42.72	0.11	13.65	1313.44	3.19 × 10⁸
950	γ	36.02	34.59	25.95	0.91	2.53	1190.08	2.89 × 10⁸
950	σ	29.04	14.82	42.02	0.12	13.99	1190.08	2.89 × 10⁸
1000	γ	35.8	33.92	26.53	0.88	2.86	984.59	2.39 × 10⁸
1000	σ	28.98	15.21	41.35	0.13	14.33	984.59	2.39 × 10⁸

Table 2 Values of parameters used for the current model prediction for precipitation in N08028 alloy.

Parameter	Value	Parameter	Value
k (J/K)	1.38 × 10^-23	D₀ (m²/s)	1 × 10^-4
N_A (mol^-1)	6.02 × 10²³	Q_D (kJ/mol)	277
R (J/(mol K))	8.314	γ_γγ (J/m²)	0.4
h (J s)	6.626 × 10^-34	γ_γσ (J/m²)	0.7
Q_m (J)	4.59 × 10^-19	R_γ (μm)	39.25

Table 3 Measured and fitted values of parameters used for the current model prediction for precipitation at various temperatures (T: temperature).

T (oC)	f₀	f₁₀	f₂₀	k_r	t₀ (s)	N₁	τ₁	N₂	τ₂
1000	1.11 × 10^-1	6.11 × 10^-2	5.02 × 10^-2	1.22 × 10^-2	8.77 × 10³	5.73 × 10²³	2.06 × 10^-14	1.57 × 10²⁶	1.21 × 10^-10
950	1.55 × 10^-1	6.94 × 10^-2	8.57 × 10^-2	1.81 × 10^-2	7.33 × 10³
900	2 × 10^-1	7.41 × 10^-2	1.26 × 10^-1	2.79 × 10^-2	5.81 × 10³

Fig. 6. Comparison of the predicted (line) and experimental (symbols) size (length) of precipitates in GIs at various aging temperatures.

Fig. 7. Comparison of the experimental (symbols) and predicted (line) σ phase fractions during the entire precipitation, f, intergranular precipitation, f1, and intragranular precipitation, f2, at aging temperatures of (a) 1000 °C, (b) 950 °C and (c) 900 °C.

Fig. 8. Evolutions of driving force and activation energy versus aging temperatures (a) and evolutions of total effective activation energy with transition (b).

References

[1]	L. Wang, F. Liu, J.J. Cheng, Q. Zuo, C.F. Chen, J. Alloys. Compd., 623(2015), 69-78.
[2]	L. Zhang, J.A. Szpunar, R. Basu, J. Dong, M. Zhang, J. Alloys. Compd., 616(2014), 235-242.
[3]	J.L. del Abra-Arzola, M.A. García-Rentería, V.L. Cruz-Hernández, J. García-Guerra, V.H. Martínez-Landeros, L.A. Falcón-Franco, F.F. Curiel-López, Wear, 400-401(2018), 43-51.
[4]	E.M. Carnicom, T. Kong, T. Klimczuk, R.J. Cava, Solid State Commun.,284-286(2018), 96-101.
[5]	T.H. Lee, C.S. Oh, C.G. Lee, S.J. Kim, S. Takaki, Scripta Mater., 50(2004), 1325-1328.
[6]	L. Niewolak, L. Garcia-Fresnillo, G.H. Meier, W.J. Quadakkers, J. Alloys. Compd., 638(2015), 405-418.
[7]	D.M.E. Villanueva, F.C.P. Junior, R.L. Plaut, A.F. Padilha, Mater. Sci. Technol., 22(2006), 1098-1104.
[8]	C. Gennari, L. Pezzato, E. Piva, R. Gobbo, I. Calliari, Mater. Sci. Eng. A, 729(2018), 149-156.
[9]	T.H. Lee, S.J. Kim, Y.C. Jung, Metall. Mater. Trans. A, 31(2000), 1713-1723.
[10]	S. Fukumoto, Y. Oikawa, S. Tsuge, S. Nomoto, ISIJ Int., 50(2010), 445-449.
[11]	Q. Zuo, F. Liu, L. Wang, C. Chen, Z. Zhang, Mater. Sci. Technol., 31(2014), 1288-1297.
[12]	T.H. Chen, J.R. Yang, Mater. Sci. Eng. A, 311(2001), 28-41.
[13]	C.C. Hsieh, W. Wu, ISRN Metall., 2012 (2012), 361-381.
[14]	A.A. Popov, A.S. Bannikova, S.V. Belikov, Phys. Met. Metallogr., 108(2009), 586-592.
[15]	J.C. Spadotto, J. Dille, M. Watanabe, I.G. Solórzano, Mater. Charact., 140(2018), 113-121.
[16]	P.M. Cheng, G.J. Zhang, J.Y. Zhang, G. Liu, J. Sun, Mater. Sci. Eng. A, 640(2015), 320-329.
[17]	M.H. Lewis, Acta Metall., 14(1966), 1421-1428.
[18]	S. Zhang, Z. Jiang, H. Li, B. Zhang, S. Fan, Z. Li, H. Feng, H. Zhu, Mater. Charact., 137(2018), 244-255.
[19]	J. Barcik, Met. Trans. A, 14(1983), 635-641.
[20]	J.R. Tolchard, A. S?mme, J.K. Solberg, K.G. Solheim, Mater. Charact., 99(2015), 238-242.
[21]	M.L. Saucedo-Mu?oz, V.M. Lopez-Hirata, E.O. Avila-Davila, Dulce, V. Melo-Maximo, Mater. Charact., 60(2009), 829-833.
[22]	Q. Zuo, F. Liu, L. Wang, C. Chen, Metall. Mater. Trans. A, 44(2013), 3014-3027.
[23]	F. Long, Y.S. Yoo, C.Y. Jo, S.M. Seo, H.W. Jeong, Y.S. Song, T. Jin, Z.Q. Hu, J. Alloys. Compd., 478(2009), 181-187.
[24]	W. Qin, N.A.P.K. Kumar, J.A. Szpunar, J. Kozinski, Acta Mater., 59(2011), 7010-7021.
[25]	T. Sourmail, H.K.D.H. Bhadeshia, Calphad, 27(2003), 169-175.
[26]	D.A. Porter, K.E. Easterling, Phase Transformations in Metals and Alloys, third ed., CRC Press, Boca Raton, 2009.
[27]	S.H. Nedjad, M.N. Ahmadabadi, T. Furuhara, Mater. Sci. Eng. A, 490(2008), 105-112.
[28]	T. Koutsoukis, A. Redja?mia, G. Fourlaris, Mater. Sci. Eng. A, 561(2013), 477-485.
[29]	W. Xu, D.S. Martin, P.E.J. R.D. del Castillo, S. van der Zwaag, Mater. Sci. Eng. A, 467(2007), 24-32.
[30]	P. Bruna, D. Crespo, R. González-Cinca, E. Pineda, J. Appl. Phys., 100(2006), 054907.
[31]	F. Liu, F. Sommer, C. Bos, E.J. Mittemeijer, Int. Mater. Rev., 52(2007), 193-212.
[32]	T. Pradell, D. Crespo, N. Clavaguera, M.T.Clavaguera-Mora, J. Phys. Condens. Matter, 10(1998), 3833-3844.
[33]	T. Sourmail, H.K.D.H. Bhadeshia, Calphad, 27(2003), 169-175.
[34]	H.B. Aaron, D. Fainstein, G.R. Kotler, J. Appl. Phys., 41(1970), 4404-4410.
[35]	F. Liu, F. Sommer, E.J. Mittemeijer, Chongqing Environ., 39(1999), 1621-1634.
[36]	S. Crusius, U. Knoop, G. Inden, L. Hoglund, J. Agren, Z. Metallkd., 83(1992), 729-738.
[37]	H.I. Aaronson, M. Enomoto, J.K. Lee, Mechanisms of Diffusional Phase Transformations in Metals and Alloys, CRC Press, Boca Raton, 2010.
[38]	K. Fan, F. Liu, X.N. Liu, Y.X. Zhang, G.C. Yang, Y.H. Zhou, Acta Mater., 56(2008), 4309-4318.
[39]	A.T. Dinsdale, Calphad, 15(1991), 317-425.
[40]	N. Dupin, B. Sundman, Scand. J. Metall., 30 (2010), 184-192.
[41]	K.L. Yam, Welding Metallurgy and Weldability of Nickel-Base Alloys, John Wiley & Sons, Hoboken, New Jersey, 2009.