Investigation on the High-Temperature Oxidation Resistance of Ni-(3~10) Ta and Ni-(3~10) Y Alloys

Hang Duan,Tiesong Lin,Yan Liu,Hui Zhang,Zhengren Huang

doi:10.3390/met9010097

Abstract

Ni-(3~10) Ta and Ni-(3~10) Y alloys were fabricated by vacuum arc melting. The oxidation resistance of the alloys was studied by cyclic and isothermal oxidation tests at 800 °C in static air. The present work focused on the investigation of the effects of the alloying elements (Ta and Y) on the oxidation behavior of Ni-based alloys. The oxidation behavior of alloys was evaluated by mass gain, composition, as well as the microstructure of oxidized products. The experimental results indicated that Ta at a low content (3 wt %) had a positive role in enhancing oxidation resistance by decreasing the oxygen vacancy concentration of the oxide layer to prevent the inward diffusion of oxygen during oxidation, and the mass gain decreased from 2.9 mg·cm−2 to 1.7 mg·cm−2 (800 °C/200 h), while Y (3~10 wt %) degraded the oxidation resistance. However, it is worth mentioning that the pinning effect of Y2O3 increased the adhesion between the substrate and oxide layer by changing the growing patterns of the oxide layer from a plane growth to fibrous growth. Among the results, the bonding of the substrate and oxide layer was best in the Ni-3Y alloys.

Highlights

Ni-based alloys have remarkable mechanical properties and excellent oxidation resistance at high temperatures
Cr in Ni-based alloys can result in Cr volatilization and deposition on the cathode, which can significantly degrade solid oxide fuel cell (SOFC) performance [7,8]
Interconnects must work at high temperatures without a decline in electrical properties and oxidation resistance

Summary

Introduction

Ni-based alloys have remarkable mechanical properties and excellent oxidation resistance at high temperatures. These alloys are used extensively for high-temperature industrial applications, such as aerospace systems, gas turbine blades, and interconnects of solid oxide fuel cell (SOFC) [1,2,3]. In these applications, with the working temperature of SOFC decreasing to an intermediate temperature (600–800 ◦ C), metallic materials (Fe-based, Ni-based, and Cr-based alloys) as interconnects become feasible [4,5,6]. Interconnects must work at high temperatures without a decline in electrical properties and oxidation resistance

Methods

Results

Conclusion