| LI Yong-quan,DU Xiao-juan,JIANG Liang,ZHANG Xiao-li,WEI Jie.Effects of Active Element Y on Formation of Silicide Co-deposition Coatings on High Nb-TiAl Alloy[J],45(10):28-33 |
| Effects of Active Element Y on Formation of Silicide Co-deposition Coatings on High Nb-TiAl Alloy |
| Received:April 18, 2016 Revised:October 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.10.005 |
| KeyWord:TiAlNb9 alloy Si-Y co-deposition coating microstructure active element Y |
| Author | Institution |
| LI Yong-quan |
School of Material Science & Engineering, Beifang University of Nationalities, Yinchuan , China |
| DU Xiao-juan |
Measuring Physical and Chemical Center, Special Energy Group of Xi'an Qinghua, Xi'an , China |
| JIANG Liang |
School of Material Science & Engineering, Beifang University of Nationalities, Yinchuan , China |
| ZHANG Xiao-li |
School of Material Science & Engineering, Beifang University of Nationalities, Yinchuan , China |
| WEI Jie |
School of Material Science & Engineering, Beifang University of Nationalities, Yinchuan , China |
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| Abstract: |
| The work aims to improve high temperature oxidation resistance of Nb-TiAl alloy. In this paper, Y modified silicide coating was prepared on high Nb-TiAl surface by taking NaF as catalyst and diffusing and co-penetrating Si-Y for 5 h under 1080 ℃. Effects of Y2O3 content in permeating agent on co-deposition coating and its phase composition were analyzed by virtue of XRD, SEM and EDS. All Si-Y coatings prepared with different contents of Y2O3 were provided with a multi-layer composite structure. Thickness of the coatings firstly increased and then decreased with the addition of Y element in the pack. All inlayers of the coatings were mainly composed of a γ-TiAl phase. The outer layers of the coatings prepared at 1080 ℃ for 5 h with the pack mixture containing 2% or 3% Y2O3 were mainly composed of (Ti，Nb)Si2 phase, and the middle layer was divided into upper and lower layers composing of (Ti, X)5Si4 and (Ti, X)5Si3 respectively. Moreover, a superficial layer consisting of Al-rich (Ti,Nb)5Si4 and (Ti,Nb)5Si3 was detected in the coating prepared with 2% Y2O3. However, the constituent phase turned to (Ti, Nb)5Si4 in the out layer and (Ti, X)5Si3 in the middle layer of the co-deposition coating when the pack mixture contained 0%, 1% or 5% Y2O3. The coating growth can be catalyzed obviously when the content of Y2O3 in the pack mixtures ranges between 2%~3%. However, excess addition of rare earth element will restrain the adsorption and diffusion of Si element, and thus a number of holes will appear on Si-Y co-deposition coating and the layer structure will change. |
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