JOM

, Volume 67, Issue 11, pp 2646–2652 | Cite as

Effects of Mo/Si Ratio Inversion on the Oxidation of Nb-Cr-Mo-Si-B Alloys

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Abstract

The effect of inverting the Mo/Si ratio on the oxidation of two boron-containing alloys has been studied in air for temperatures 700–1400°C. The compositions of the alloys in atomic percent are Nb-25Cr-20Mo-15Si-15B, Nb-25Cr-20Mo-15Si-10B, Nb-25Cr-15Mo-20Si-10B, and Nb-25Cr-15Mo-20Si-15B hereafter referred to as 10B, 15B, 2010, and 2015 alloys, respectively. The as-cast microstructure of the alloys contains a mixture of NbCr2 Laves phase, Nb5Si3 silicide, and additionally Nb3Si silicide for the Mo/Si modified alloys. Primary oxides developed for all alloys are CrNbO4, Nb2O5, and SiO2. Improvements in high-temperature oxidation have been seen for the Mo/Si-modified 15B containing alloy under cyclic testing. Samples have shown similar oxidation responses in both long-term static and cyclic oxidation for 168-h exposures up to 1300°C. Characterization of oxide products was done by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy.

Keywords

Oxide Scale Electric Discharge Machine Oxidation Resistance Nb2O5 Cyclic Oxidation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Notes

Acknowledgements

K.S. Thomas would like to thank The University of Texas at El Paso and the PNE project led by Dr. Peter Kim for their financial assistance.

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Copyright information

© The Minerals, Metals & Materials Society 2015

Authors and Affiliations

  1. 1.Department of Metallurgical and Materials EngineeringThe University of Texas at El PasoEl PasoUSA

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