Figures index

From

On the Role of Boride in the Structural Integrity of a Turbine Disc Superalloy’s Solid State Weld

K.M. Oluwasegun, J.O Olawale, M.D. Shittu, O.O. Ige, P.O. Atanda, O.O. Ajide, L.O. Osoba

American Journal of Materials Engineering and Technology. 2017, 5(1), 14-23 doi:10.12691/materials-5-1-3
  • Figure 1. (a) SEM image of alloy ‘X’ showing γ' precipitates and grain boundary borides (insert arrows in ‘a’) (b) representative image J output for area fraction (%) quantification of boride in ‘a’ (c) TEM BF image of M3B2 boride (d) TEM EDX of M3B2 boride with strong Mo and Cr peaks.
  • Figure 2. SADPs taken from a boride particle along three zone axes; used to confirm the crystal structure (bct) and lattice parameter of the boride. (b) A schematic Kikuchi pattern along the three zone axes in ‘a’.
  • Figure 3. Thermo-Calc for (a) the nominal composition of the parent alloy, showing phase fraction vs temperature (Note that the predicted phases labelled 3, 6, 7, 8 and 9 were not observed in this work) (b) the composition of M3B2 boride. It predicts the onset of melting of the boride to be about 1200°C (insert black arrow)
  • Figure 4. (a) SEM micrographs showing liquated boride along a grain boundary (GB) (b) a micrograph showing liquation products on the same GB from both boride and γ' precipitates (c) SEM EDX from the liquated boride
  • Figure 5. (a) STEM BF image of a liquated M3B2 particle and a Hf-rich oxide (b) STEM EDX maps of the liquated phase in ‘a’.
  • Figure 6. (a) SADP from the liquated boride shown in Figure 5. The bold angle is the total tilt angle while the unbold is the calculated angle. (b) Schematic Kikuchi pattern along the zones in ‘a’
  • Figure 7. (a) SEM image of MC carbide within the CLZ (b) TEM DF image of a different intergranular MC carbide within the heat affected zone with insert SADP (c) SEM EDX spectrum of the MC carbide in ‘a’. MC carbides in this region of the weld are clearly unaffected by the heat of welding
  • Figure 8. (a) STEM BF image of a liquated M3B2 particle associated with unaffected MC carbide and hafnium oxide (b) STEM EDX maps of the liquated phase in ‘a’
  • Figure 9. B-Cr-Mo phase diagram showing the effect of boron on increasing the melting temperature range of an M2B boride [25]
  • Figure 10. Stress and temperature profile during Gleeble on-heating ductility test of nickel-based superalloy with insert microstructure observed adjacent to the fractured surface. The arrows on the plot illustrate the correspondence between the temperature where liquation of the precipitates occurs and the abrupt drop in stress level