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2011-Sustainable Industrial Processing Summit
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| Editors: | Florian K |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2012 |
| Pages: | 646 pages |
| ISBN: | 978-0-9879917-6-8 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Role Of Zr In Oxidation Resistance Of Nanocrystalline Fe-Cr-Ni-Zr Alloys
B V Mahesh1; Raman Singh2; Carl C Koch3;1MONASH UNIVERSITY, Monash University, Australia; 2MONASH UNIVERSITY, Monash Univ (Melbourne), Austria; 3NORTH CAROLINA STATE UNIVERSITY, Raleigh, United States;
Type of Paper: Regular
Id Paper: 393
Topic: 9
Abstract:
This paper investigates the role of nanocrystalline grain size and effect of Zr addition in the oxidation resistance of Fe-based alloys. Nanocrystalline (nc) Fe-xCr-5Ni-2Zr and Fe-xCr-5Ni {x = 2, 4, 7, 10} alloy pellets, with grain size 50-60 nm, have been synthesized by mechanical alloying route. A novel multi-step hot-compaction process has been investigated for the consolidation into close to 100% dense nc pellets that were found to have a high hardness (8 GPa) and reasonable ductility under shear stress condition. The addition of 2% Zr improves the grain size stability upto a temperature as high as 1000oC, which can be attributed to particle pinning as well as reduction in grain boundary energy due to Zr segregation. The high temperature oxidation resistance of these alloys has been studied vis-a-vis conventional mc stainless steel alloy at 500oC for 100 hours. The kinetics of oxidation was found to be parabolic in nature. The oxide layer, as characterized by SIMS depth profiling and FIB/SEM, was found to be 0.8-1.2 μm in thickness, consisting primarily of Cr2O3 in case of both mc and nc Fe-Cr-Ni alloys. However, in case of the Fe-Cr-Ni-Zr alloys, the oxide layer comprised of Cr2O3 as well as Zr2O3 resulting in an improved oxidation resistance of Zr containing alloys.