July 17-21, 2016
Three phase Mo-9Si-8B (at.%) alloys are a prominent example for a potential new high temperature structural material. Due to their high melting point and excellent creep resistance. In this study the effect of Zr addition (0…4 at.%) on the microstructure and creep properties of Mo-9Si-8B (at.%) alloys is investigated. Two powder metallurgical processes, hot isostatic pressing (HIP) and spark plasma sintering (SPS), are used to prepare specimens. The resulting microstructures are examined using SEM and TEM analysis. SPS alloys exhibit smaller grain sizes and fewer oxides compared to the HIP alloys, because of the oxygen availability during HIP. The more Zr is present in the alloys, the more and finer the observed particles are. With addition of Zr the formation of SiO2 on the grain boundaries can be prevented completely, due to the formation of ZrO2. High temperature tensile creep tests are carried out under vacuum to determine the influence of the microstructure on creep properties. The creep rates are one order of magnitude lower for the Zr containing alloys. However with a level of 4 at.% Zr the minimum creep rates increase again.
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Uwe Glatzel, Christian Hochmuth, and Rainer Völkl, "Mo-9Si-8B alloys with additons of Zr – microstructure and creep properties" in "Beyond Nickel-Based Superalloys II", Chair: Dr Howard J. Stone, University of Cambridge, United Kingdom Co-Chairs: Prof Bernard P. Bewlay, General Electric Global Research, USA Prof Lesley A. Cornish, University of the Witwatersrand, South Africa Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/superalloys_ii/8