Study on the Pre-Oxidation and Resulting Oxidation Mechanism and Kinetics of Mo-9Si-8B Alloy.

Cheng Wang,Xiangrong Li,Xiangyu Ding,Zhenping Guo,Xin Li,Bin Li,Qiuliang Li,Zhuoyue Li

doi:10.3390/ma14185309

Abstract

Molybdenum silicon boron alloy is regarded as the next generation of superalloy that is expected to replace nickel-based superalloys. However, the high-temperature oxidation resistance of Mo-Si-B alloy has always been an issue worth studying. In this study, Mo-9Si-8B alloy was prepared via a plasma oscillatory pressure sintering process and pre-oxidized at 1300 °C while maintaining a certain balance of mechanical and oxidation properties. The influence of the oxide protective layer on its performance at high temperature of 1150 °C was explored, the micro-mechanism of its performance and its failure mode of the hinge-locking mechanism was illustrated, and finally, its oxidation kinetics was inferred. In conclusion, pre-oxidized Mo-9Si-8B (at.%) alloy did play a role in delaying the oxidation process during the initial period of cyclic oxidation. However, with the increase of cyclic oxidation time, the improvement of high-temperature oxidation resistance was limited.

Highlights

For existing nickel-based superalloys, they could be used at around 900 ◦ C without the coating and cooling system
Even with the addition of the coating and cooling system, the nickel-based alloy could only work at about 1150 ◦ C [1], which had reached its maximum limit and resulted in a huge reduction in the efficiency of the turbine engine
The specific strength and oxidation resistance of Nb-Si alloy above 1300 ◦ C were obviously weaker than that of Mo-Si alloy [1,2,3,4]

Summary

Introduction

For existing nickel-based superalloys, they could be used at around 900 ◦ C without the coating and cooling system. Even with the addition of the coating and cooling system, the nickel-based alloy could only work at about 1150 ◦ C [1], which had reached its maximum limit and resulted in a huge reduction in the efficiency of the turbine engine. The specific strength of the Si-C ceramic matrix composites was low, and its intrinsic brittleness was too large It was not suitable for load-bearing parts of complex shapes in high-temperature circumstances, and it was difficult to connect ceramic matrix composites with metal materials [3]. The Mo-Si-B alloy exhibited outstanding mechanical properties, high-temperature oxidation resistance, good creep resistance, and high melting point. It is hard for the Mo-Si-B alloy to keep both the mechanical properties and Materials 2021, 14, 5309 the mechanical properties and high‐temperature oxidation resistance excellent. While maintaining certainoxidation mechanical properties, it is stillWhile a problem to continue to maintain and high-temperature resistance excellent

Methods

Results

Conclusion