Effect of Si addition on the creep performance of a Ni-based superalloy

Abstract

In this research, the effect of two different per centages of silicon, i.e. 0.08 and 0.3 wt-%, on microstructure and stress rupture life of a Ni-based superalloy was investigated. The results showed that the fraction of eutectic increased from 1.86 to 3.55% with increasing Si content and a higher fraction of eutectic was found on grain boundaries in high Si-bearing alloy. Upon stress rupture at 975°C/225 MPa, cracking initiates and propagates along Laves phases in 0.3 wt-% Si alloy, causing shorter lifetime comparing to that of 0.08 wt-% Si. The microscopic examination uncovered that Si prefers to segregate towards liquid and γ phase, which can explain different rupture lifetimes of two groups of Si-bearing alloys.

KEYWORDS:

• Ni-based superalloy
• Si content
• Laves phase
• eutectic
• stress rupture

Acknowledgements

The authors acknowledge the financial support from the National Key Research and Development Program of China (2018YFB0704100). Z. H. appreciates the project supported by State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China. And this work was supported by the Opening Project of State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilisation.

Disclosure statement

The authors declare no potential conflict of interest.

Additional information

Funding

This work was supported by the Opening Project supported by the State Key Laboratory of Nickel and Cobalt Resources Comprehensive Utilization (Jinchuan group, China); National Key Research and Development Program of China: [Grant Number 2018YFB0704100]; State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China.