Effect of the Electrodeposition Temperature on the Cyclic-Oxidation Resistance of Ni Aluminide Containing Zr Formed by Molten-Salt Electrodeposition

Abstract

The effect of the Al electrodeposition temperature on the cyclic oxidation resistance of Ni aluminide containing Zr formed by molten salt electrodeposition was investigated. Zr and Al were deposited by molten salt electrolysis. For the sample treated with the Al deposition at 1073 K, a layer consisting of Ni2Al3 was uniformly formed. On the other hand, for the sample treated by Zr deposition, followed by Al deposition at 1073 K, a layer consisting of Ni2Al3 and a Ni aluminide layer containing Zr on the Ni2Al3 layer were formed. Furthermore, when the Al electrodeposition temperature was changed, the concentration of Zr in the Ni aluminide layer containing Zr changed. When the Al electrodeposition was carried out at 1153 and 1173 K, the Zr was scarcely observed in the surface region of the Ni aluminide layer. The cyclic oxidation test showed that for the sample treated with only the Al deposition and the sample treated with the Zr deposition, followed by Al deposition at 1073 K, a mass reduction due to scale exfoliation took place, whereas for the samples treated with the Zr deposition, followed by Al deposition at 1153 and 1173 K, no mass reduction was observed. For these samples, after the cyclic oxidation test, a scale consisting of � -Al2O3 adhering to the substrate was formed. Consequently, it was found that the cyclic oxidation resistance of Ni was improved by Zr deposition, followed by Al deposition at 1153 and 1173 K. [doi:10.2320/matertrans.MRA2008293]