Initial oxidation behavior of a single crystal superalloy during stress at 1150\u2009\xb0C

Jinyao Ma,Jin Wang,Yuefei Zhang,Ze Zhang,Wenxiang Jiang

doi:10.1038/s41598-020-59968-3

Jinyao Ma, Jin Wang + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-59968-3

Copy DOI

Abstract

Revealing the initial oxidation behavior of single crystal superalloys is significant for a better understanding of the oxidation mechanism of turbine blades during service condition. The purpose of current research was to observe the initial oxidation of a single crystal superalloy. In-situ oxidation experiment during only thermal exposure and thermal-stress pattern were carried out. The mechanism of nucleation and growth of oxide scale was discussed. Results showed that the oxide on the interface of γ/γ′ phase was constituted of Al2O3 precipitates and formed by external diffusion of Al atoms or ions. Loading stress enhanced the diffusion of Al atom causing high oxidation rate. A logarithmic model was proposed and fitted well with the oxidation process.

Highlights

Nickel-based single crystal superalloys have been widely used in turbine blades and other hot-end components of modern aeroengines due to their excellent creep and mechanical properties[1,2]
Though there are extensive researches focusing on oxidation behavior of superalloy during intermediate and high temperature[10,11,12], the initial oxidation process has not been observed clearly considering the rapid formation of adherent oxide scale
Through in-situ environmental transmission electron microscopy (ETEM), initial oxidation at only thermal exposure was observed by Ding[13], and gave the proof that oxygen diffusion path is more inclined to be the interface rather than matrix channels[14]

Summary

Introduction

Nickel-based single crystal superalloys have been widely used in turbine blades and other hot-end components of modern aeroengines due to their excellent creep and mechanical properties[1,2]. To improve turbine efficiency, increasing turbine entry temperature is challenging superalloy’s operational limits[3] Such high temperature causes the rotating components (turbine discs and blades) to bear high centrifugal stresses[4]. Except for high temperature and heavily stress, oxidation and hot corrosion unavoidably degrade the performance of turbine blades during service condition[5,6]. Microstructure evolution during oxidation of a nickel-based single crystal superalloy during only thermal exposure and thermal-stress pattern was studied by carrying out in-situ experiments in scanning electron microscope (SEM) at 1150 °C and 1150 °C/330 MPa under an oxygen partial pressure of 2 × 10−9 atm.

Methods

Discussion

Conclusion