Secondary M6C Precipitation in Ni-20Cr-18W-1Mo Superalloy
Jingqing Zhang1, Rui Hu2, Jian Wang3, Jinshan Li4
1Jingqing Zhang, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, China.
2Rui Hu, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, China.
3Jian Wang, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, China.
4Jinshan Li, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, China.
Manuscript received on 10 November 2013 | Revised Manuscript received on 18 November 2013 | Manuscript Published on 30 November 2013 | PP: 48-51 | Volume-3 Issue-6, November 2013 | Retrieval Number: F1342113613/13©BEIESP
Open Access | Editorial and Publishing Policies | Cite | Mendeley | Indexing and Abstracting
© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: The carbide precipitation behavior in Ni-20Cr-18W-1Mo superalloy solution treated at 1280 oC and then aged at 800 and 1000 oC has been investigated using SEM, EDS and TEM in the present work. Since the content of W and Mo is high enough (>6-8 wt.%) and the value of proportion (Cr at.% /(Cr+Mo+0.7W) at.% ) is 0.8206, satisfying the condition for the formation of secondary M6C, it is granular and W-rich M6C as secondary phase instead of lamellar and Cr-rich M23C6 that precipitates at grain boundaries when the aging temperature is not lower than 1000 oC. The precipitation of secondary M6C is suggested through a direct reaction between the metal elements and carbon atoms mechanism, in which the decomposition of primary M6C carbide provides the necessary elements. M is mainly W element with modest level of Ni, Cr and Mo. The result provides a foundation for improving the mechanical property of the alloy.
Keywords: Ni-20Cr-18W-1Mo Superalloy, Carbide, Secondary M6C, Grain Boundary.
Scope of the Article: Mechanical Design