|
|
|
| INVESTIGATION OF CoO INOCULANT FOR SURFACE GRAIN REFINEMENT OF CAST NICKEL-BASE SUPERALLOY BLADES |
| Zhao Huitian and Shi Changxu (Institute of Metal Research; Academia Sinica) |
|
Cite this article:
Zhao Huitian and Shi Changxu (Institute of Metal Research; Academia Sinica). INVESTIGATION OF CoO INOCULANT FOR SURFACE GRAIN REFINEMENT OF CAST NICKEL-BASE SUPERALLOY BLADES. Acta Metall Sin, 1981, 17(2): 118-123.
|
|
|
Abstract The CoO inoculant composed of 20% CoO and 80% Al_2O_3 (fused alumina) is an effective nucleator to the cast nickel-base superalloy blades. After calcining CoO and Al_2O_3 powders under 1300℃ for 2h, CoO.Al_2O_3 spinel was formed on the surface of alumina particles. It has been detected by EMPA that metallic Co of fcc crystal structure deposites on the surface due to that the CoO.Al_2O_3 spinel reduced by certain active elements contained in the cast nickel-base superalloys at elevated temperature. This is checked with the relative stabilities of the oxides of Ti, Cr, Al contained in the alloy with CoO. This was also verified by the pure Ni blades for which there was no effect at all. Because of the similarity of the crystal structure and the lattice constants of the metallic Co and the superalloy, the Co particles can act as nucleators refining the grains. In production practice, if SiO_2 is precipitated in local area of inner surface of mould and so the inoculant particles were covered with it, the nucleation effect is markedly reduced. In order to prevent the metallic Co remelting back, lower pouring temperature is preferred; and to enhance the reduction of CoO.Al_2O_3, higher heating temperature of mould is desirable.
|
|
Received: 18 February 1981
|
[1] 依田连平,金属材料,10(1970) ,49．
[2] Feagin, R. C., Dipcoat Nucleation, Proceedings of 12th Conference, 1967, XII-1．
[3] Chales, M., Foundry, 90 (1962) , № 8, 44． |
| No Suggested Reading articles found! |
|
|
Viewed |
|
|
|
Full text
|
|
|
|
|
Abstract
|
|
|
|
|
Cited |
|
|
|
|
| |
Shared |
|
|
|
|
| |
Discussed |
|
|
|
|
