Oxidation behavior of Zr-10Nb-10Ti and Zr-10Nb-20Ti (compositions are in atomic percent) alloys has been investigated in air between 300 and 700°C. Higher Ti content in the alloy enhances the oxidation resistance. The calculated isotherms by Pandat™ [1,2] show that 20Ti enters a 3 phase (αZr-HCP, βNb-BCC, and βZr-BCC) region at 500°C while 10Ti alloy continues to be a 2 phase (αZr and βNb) alloy until 550°C and then enters the 3 phase (αZr, βNb, and βZr) region. Both alloys have a single phase β Zr solid solution at 700°C which is detrimental for the oxidation resistance. β Nb-phase greatly contributes to the oxidation resistance in these two alloys. The common oxidation products have been identified as TiO2, ZrO2, and Nb 2O5. Formation of substoichimoetric structures has been observed at lower temperatures. Both alloys suffer from pest oxidation at temperatures between 500 and 550°C, respectively (20Ti and 10Ti), up to 700°C. XRD indicates strong peaks for monoclinic structure of ZrO2 at temperatures above 600°C. Vickers micro-hardness measurements for the as-cast alloys and Rockwell Hardness measurements were conducted on the as-cast and after experimental exposure alloys, in order to obtain some sense of the mechanical properties of the alloys. Increased hardness is related to the formation of β Zr phase in the microstructure.
|Advisor:||Varma, Shailendra K.|
|Commitee:||Noveron, Juan C., Trueba, Luis|
|School:||The University of Texas at El Paso|
|Department:||Metal And Mat'l Eng.|
|School Location:||United States -- Texas|
|Source:||MAI 48/04M, Masters Abstracts International|
|Keywords:||Microstructures, Niobium, Oxidation, Titanium, Zirconium|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be