Effect of 10 at.% Nb Addition on Sintering and High Temperature Oxidation of W0.5Cr0.5 Alloy

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The effect of 10 at.% Nb on the sintering and high temperature oxidation behavior of W0.5Cr0.5 alloy was investigated. Elemental powder blends were made nanostructured by high energy mechanical milling, compacted and finally sintered under reduced atmosphere at 1790°C. The sintered samples were subjected to cyclic isothermal oxidation tests at 800°C to 1200°C in air. The experimental results shows superior sinterability and oxidation protection of W0.5Cr0.5 alloy compared to pure W. Characterization of the oxide scales shows porous external W-rich oxide (WO3) formation which is not ideally suitable for oxidation resistance. On the other hand, W-Cr alloy with 10 at.% Nb shows the remarkable sinter densification (~98%) and oxidation resistance up to 1200°C. The oxide scale of the ternary alloy shows formation of stable Cr2O3, Nb2O5 oxides and/or complex Cr-Nb oxide (CrNbO4), and there was no evidence of WO3 formation in this case.

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308-313

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January 2012

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© 2012 Trans Tech Publications Ltd. All Rights Reserved

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[1] W. F. Smith, Structure and properties of engineering alloys, second ed., McGraw-Hill, New York, 1993, pp.580-586.

Google Scholar

[2] E. Lassner, W.D. Schubert, Tungsten Properties, Chemistry, Technology of The Elements, Alloy and Chemical Compound, Kluwer Academic / Plenum Publishers, New York, 1998, pp.28-42.

Google Scholar

[3] W. W. Webb, J. T. Norton, C. Wagner, Oxidation of tungsten, J. Electrochem. Soc. 103 (1956) 107-111.

Google Scholar

[4] J. W. Semmel, High Temperature Materials, John Wiley Sons, Inc, New York, 1959, pp.510-519.

Google Scholar

[5] R. Malewar, K. S. Kumar, B. S. Murty, S. K. Pabi, On sinterability of nanostructured W produced by high-energy ball milling, J. Mat. Res., 22 (2007) 1200-1207.

DOI: 10.1557/jmr.2007.0166

Google Scholar

[6] D. S. Evans, Oxidation of alloys W-Cr-Pd, High Temperature Materials, 6th Plansee Seminar, Metallwerk-Plansee, Austria, 1968. p.42.

Google Scholar

[7] F. H. Stott, G. C. Wood, J. Stringer, J, The influence of alloying elements on the development and maintenance of protective scales, Oxi. Met., 44 (1995)113-145.

DOI: 10.1007/bf01046725

Google Scholar

[8] Suklyun Hong, C. L. Fu., Phase stability and elastic moduli of Cr2Nb by first-principles calculations, Intermetallics, 7 (1999) 5-9.

DOI: 10.1016/s0966-9795(98)00005-3

Google Scholar