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| EFFECT OF ALLOYING ELEMENTS TO HOT CORROSION BEHAVIOR OF NOVEL Co-Al-W SUPERALLOY |
| XU Yangtao1,2, XIA Tiandong1,2, YAN Jianqiang1,2 |
1. State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050
2. Key Laboratory of Non-ferrous Metal Alloys, Ministry of Education，Lanzhou University of Technology，Lanzhou 730050 |
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Abstract Co-Al-W alloy is a kind of novel Co-based superalloy strengthened by ternary compound γ'-Co3(Al,W) phase with the precipitation strengthening on γ-Co matrix. The paper studies the kinetic of hot corrosion of Co-Al-W superalloy at 800℃ in 75% Na2SO4+25\% NaCl molten salt and the effect on hot corrosion behavior of Co-Al-W alloy with alloying elements of Mo, Nb, Ta and Ti. The results show that the alloy of 2Mo, 2Nb, 2Ta and 2Ti have the superior anti-hot corrosion ability compared to 9.8W alloy. The anti-hot corrosion ability of Co-Al-W alloy with alloying elements Ta and Nb are inferior to Co-Al-W alloy adding Mo and Ti elements. The hot corrosion oxide scale with alloying elements of Mo, Nb, Ta and Ti is still made up of three layers, that is the external corrosion layer consists of Co oxide CoO and Co3O4, the intermediate mixed oxides layer composed of complex oxide and nonuniform oxide layer of alloying elements, Co, Al, W and an internal attacked layer with different compounds of Co, Al and O. With the increasing of corrosion times, the intermediate mixed oxides layer becomes thicker, the thickness of internal and external layer almost has no change, but compactness of internal layer is gradually increased.
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Received: 19 October 2009
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