1700 L. γ+hcp+γ'+μ Al content, CAl (mass%)

Transcription

1 1700 L 1500 γ Temperature, T (K) γ+μ γ+ γ'+μ γ+ γ'+μ+σ 900 γ+hcp+γ'+μ γ+ γ'+hcp+μ Al content, CAl (mass%) Supplementary Figure 1 Equilibrium phase diagram. The calculated equilibrium phase diagram for the alloy Co-35Ni-17.5Cr-8Mo-3Nb-1.6Fe-0.8Ti-xAl, indicating the possible formation of single phase above 1200 K and precipitations of γ' phase and phase below 1200 K at an Al concentration of 2%. 1

2 3000 Intensity in a.u Experimental Fitted γ γ' Supplementary Figure 2 X-ray diffraction analysis. Typical example of peak fitting of the two hidden peaks of γ and γ' phases using the least square fitting for the alloy Co- 35Ni-17.5Cr-8Mo-3Nb-1.6Fe-0.8Ti-2Al. The alloy was swaged by 20% and aged at 1073 K for 3 h (S20AG). 2

3 Supplementary Table 1 Six groups of samples prepared at various treatment conditions. Group Num. Abbreviation Treatment (1) ST Solution treatment (2) AG ST-1073 K 3 h (3) S20 ST-Swage20% (4) S20AG ST-Swage20%-1073 K 3 h (5) S66 ST-Swage66% (6) S66AG ST-Swage66%-1073 K 3 h 3

4 Supplementary Table 2 Lattice misfit for the alloys prepared at different working and aging conditions. Alloy 2θ (311) a Misfit (%) AG S20AG S66AG S20AG h γ γ' γ γ' γ γ' γ γ'

5 Supplementary Discussion Calculated phase diagram Phase diagram was calculated using the Thermal-Calc software. The nickel-base alloy Ni17 thermodynamic database was applied. Supplementary Fig. 1 shows calculated phase diagram of the alloy Co-35Ni-17.5Cr-8Mo-3Nb-1.6Fe-0.8Ti-xAl (mass%). The Al concentration is adopted to be 2%. From this figure, the single γ phase can be obtained at above 1200 K. Apart from the γ phase, the γ' and phase (Co7Mo6, rhombohedral lattice belonging to the 5 D3 d R3m space group) can also be obtained. However, the phase cannot be observed frequently in the present alloy at the present aging conditions. Lattice mismatch Calculations of lattice mismatch between the γ matrix and γ' phase were carried out based on the X-ray diffraction pattern, which was obtained using the PANalytical X'Pert MPD diffractometer with the Cu-Kα radiation. The 2θ of diffraction peak of each phase was calculated from the hidden peaks using the least square fitting in view of the crystal structure (Fig. S2). The lattice parameter a of each phase in an alloy of various states was calculated using the following equation, (1) where a is the lattice parameter, d is the interplanar spacing in FCC crystal, and h, k, l are the Miller indices. The interplanar spacing d can be calculated by 5

6 , (2) where θ is the measured angle using X-ray diffraction, and is the wavelength of Cu-Kα ( nm). The mismatch can be calculated using the following equation 2( a a a γ' a ) γ' where is lattice mismatch, and αγ and αγ' are the lattice constants of the γ and γ' phase, respectively. Table 2 lists the calculated lattice mismatch of the alloys prepared at various conditions, confirming the extremely low lattice mismatch. (3) Working and heat treatment conditions of superalloys TMW-4 alloy Ni-26.2Co-14.9Cr-2.8Mo-1.1W-1.9Al-6.1Ti (mass%) was fabricated by hot rolling (75%) at 1373 K, followed by the solution treatment at 1373 K for 4 h. The alloy was then aged at 923 K for 24 h, followed by air cooling. Next, it was aged at 1033 K for 12 h, followed by air cooling 1. Inconel 718 alloy Fe-50Ni-17Cr-0.35Al-2.8Mo- 0.65Ti was solution treated at 1227 K and aged at 991 K and 894 K 2. The nickel-base Rene88DT alloy Ni-15.7Cr-12.9Co-3.98Mo-3.98W-3.84Ti-2.21Al-0.72Nb was prepared by powder metallurgy and solution treated at 1450 K, followed by aging at 1033 K for 8 h 3. U720Li alloy Ni-14.4Co-16Cr-4.93Ti-2.97Mo-2.49Al-1.21W was solution treated at 1363 K for 4 h followed by oil quenching. It was then aged at 923 K for 24 h, followed by air cooling, and aged again at 1033 K for 16 h, followed by air cooling 4. Co-W-Al alloy Co-46.3Ni-15.9W-3.6Al-2.9Ta-8.2Cr was hot forged at 1473 K, followed by water quenching. It then underwent solution treatment at 1473 K for 1 h by water quenching. 6

7 Next, it was aged at 1023~1173 K for 48 h, followed by air cooling 5. AM 350 alloy Fe Cr-4.45Ni-2.95Mo-0.37Si-1.02Mg-0.094C was annealed at 1283 K, followed by a rapid cooling. It was then aged at 1005 K for 1.5 h, followed by air cooling. The alloy was next aged again at 713 K for 2 h, followed by air cooling 6. The as-casted Inconel 713C alloy Ni-12.5Cr-2.2(Co+Ta)-4.2Mo-6.1Al-0.8Ti was heat treated at 1352 K for 1 h 7. Waspaloy alloy Ni-13.5Co-19Cr-4.3Mo-1.5Al-3Ti-2Fe was solution treated at 1373 K for 2 h, followed by oil cooling. It was then aged at 1003 K for 6 h, followed by air cooling 2. L605 alloy Co-9Ni-19Cr-14W-1Mg-0.05C was solution treated at a temperature ranging from 1450 to 1505 K, followed by either rapid air cooling or water quenching 8. SPRON 510 alloy Co-32.9Ni-20.1Cr-10.1Mo-1.04Nb-1.79Fe-0.44Ti was solution treated at 1323 K for 12 h, followed by water quenching 9. 7

8 Supplementary References 1. Gu, Y. et al. New ni-co-base disk superalloys with higher strength and creep resistance. Scr. Mater. 55, (2006). 2. Kennedy, R. L. ALLVAC 718PLUS TM, superalloy for the next forty years, Superalloys 718, 625, 706 and Various Derivatives 2005, E. A. Loria, Ed. TMS, 2005, pp Huron, E. S. Serrated yielding in a nickel-base superalloy, Superalloys 1992, S. D. Antolovich et al., Eds., TMS, 1992, pp Gopinath, K. et al. Tensile properties of ni-based superalloy 720Li: Temperature and strain rate effects. Metall. Mater. Trans. A. 39, (2008). 5. Osaki, M. et al. Influeces of Cr and Ta on high temperature properties of γ' strengthened Co-W-Al alloys. Denki-seiko. 83, (2012). 6. Kahlbaugh, F. C. Properties and heat treatment of am 350 steel (Tech. Rep. NOR , Northrop aircraft inc., El Segundo, 1959). 7. Schirra, J. J. et al. Mechanical property and microstructural characterization of vacuum die cast superalloy materials, Superalloys 2004, K. A. Green et al., Eds., TMS, 2004, pp Shingledecker, J. P. et al. Tensile and Creep-Rupture Evaluation of a New Heat of Haynes Alloy 25, ORNL/TM-2006/609, 2007, pp Kartika, I. et al. Deformation and microstructure evolution in Co-Ni-Cr-Mo superalloy during hot working. Metall. Mater. Trans. A. 40, (2009). 8