Creep Damage of a Re/Ru-Containing Single Crystal Nickel-Based Superalloy at Elevated Temperature

Abstract:

By means of creep properties measurement, microstructure observation and contrast analysis of dislocation configuration, the creep behavior of a 4.5%Re/3.0%Ru-containing single crystal nickel-based superalloy at elevated temperature is investigated. Results show that the creep life of the alloy at 1040°C/160MPa is measured to be 725h to exhibit a better creep resistance at high temperature. In the primary stage of creep at high temperature, the γ phase in alloy has transformed into the N-type rafted structure along the direction vertical to the stress axis, the deformation mechanism of alloy during steady state creep is dislocations slipping in γ matrix and climbing over the rafted γ phase. In the latter period of creep, the deformation mechanism of alloy is dislocations slipping in γ matrix and shearing into the rafted γ phase. Wherein the dislocations shearing into the γ phase may cross-slip from {111} to {100} planes for forming the K-W locks to restrain the slipping and cross-slipping on {111} plane, which is thought to be the main reason of the alloy having a better creep resistance. As the creep goes on, the alternate slipping of dislocations results in the twisted of the rafted γ phase to promote the initiation and propagation of the cracks along the interfaces of γ/γ phase up to creep fracture, which is thought to be the damage and fracture mechanism of alloy during creep at high temperature.

• Periodical: Key Engineering Materials (Volume 795)
• Pages: 123-129
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.795.123
• Online since: March 2019
• Authors: Guo Qi Zhao, Su Gui Tian*, Shun Ke Zhang, Ning Tian, Li Rong Liu
• Keywords: Creep, Deformation Mechanism, Dislocations Climbing, Single Crystal Nickel-Based Superalloy

References

[1] Nystrom J D, Pollock T M, Murphy W H, et al. Discontinuous cellular precipitation in a high-refractory nickel-base superalloy[J]. Metallurgical & Materials Transactions A, 1997, 28(12): 2443-2452.

DOI: 10.1007/s11661-997-0001-1

[2] Sun X F, Jin T, Zhou Y Z, et al. Research progress of Effects of nickel-base single crystal superalloys heat treatment on composition segregation and enduring properties of single crystal nickel-based superalloy[J]. Materials China, 2012, 31(12): 1-11.

[3] Zhao K, Ma Y H, Lou L H, et al. m phase in a nickel base directionally solidified alloy[J]. Materials Transactions, 2005, 46(1): 54-58.

DOI: 10.2320/matertrans.46.54

[4] Reed R C, Yeh A C, Tin S, et al. Identification of the partitioning characteristics of ruthenium in single crystal superalloys using atom probe tomography[J]. Scripta Materialia, 2004, 51(4): 327-331.

DOI: 10.1016/j.scriptamat.2004.04.019

[5] Yeh A C, Tin S. Effects of Ru on the high-temperature phase stability of Ni-base single-crystal superalloys[J]. Metallurgical & Materials Transactions A, 2006, 37(9): 2621-2631.

DOI: 10.1007/bf02586097

[6] Yeh A C, Sato A, Kobayashi T, et al. On the creep and phase stability of advanced Ni-base single crystal superalloys[J]. Materials Science and Engineering, A, 2008, 490(1): 445-451.

DOI: 10.1016/j.msea.2008.02.008

[7] Sato A, Harada H, Yokokawa T, et al. The effects of ruthenium on the phase stability of ruthenium on the phase stability of fourth generation Ni-based single crystal superalloys[J]. Scripta Materialia, 2006, 54(9): 1679-1684.

DOI: 10.1016/j.scriptamat.2006.01.003

[8] Yeh A C, Tin S. Effects of Ru and Re additions on the high temperature flow stresses of Ni-based single crystal superalloys[J]. Scripta Materialia, 2005, 52(6): 519-524.

DOI: 10.1016/j.scriptamat.2004.10.039

[9] Heckl A, Neumeier S, Göken M, et al. The effect of Re and Ru on γ/γ' microstructure, γ-solid solution strengthening and creep strength in nickel-base superalloys[J]. Materials Science & Engineering A, 2011, 528(9): 3435-3444.

DOI: 10.1016/j.msea.2011.01.023