Thermal fatigue behaviour of Al-Si coated Inconel 713 LC

The effect of single and two-stage Si modified aluminide coatings on thermal fatigue behaviour of nickel based superalloy Inconel 713LC was examined. Specimens were loaded under test condition of heating to 1100°C followed by cooling to25°C. The experimental results showed that the coatings increased thermal fatigue resistance in both crack initiation and propagation stages. The comparison of the crack growth rates indicated that both coatings imparted resistance to the crack lengthening. However, the effect of single stage coating on the fatigue resistance was superior compared with that of two-stage coating. Through scanning electron microscopy observation, it was found that the width of γ′ denuded zone was the main reason in the control of crack growth in all specimens.