Formation of Synchronous Electrodeposition of Al-Zr and Al-Hf from molten salt

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A Ni aluminide layer containing Zr and Hf was formed on a Ni specimen by the synchronous electrodeposition of Al-Zr and Al-Hf using a molten-salt bath. An electrodeposited layer consisting of Ni_2Al_3 and NiAl_3 layers, for which the ZrAl_3 particles were formed on the surface region, was formed, when the simultaneous electrodeposition of Al and Zr was carried out using the molten NaCl-KCl containing 3.5mol% AlF_3 and 0.05mol% ZrF_4. An electrodeposited layer consisting of Ni_2Al_3 and NiAl_3 layers, for which the HfAl_3 particles were formed on the surface region, was formed, when the simultaneous electrodeposition of Al and Hf was carried out using the molten NaCl-KCl containing 3.5mol% AlF_3 and 0.05mol% HfF_4. The cyclic-oxidation resistance of the Ni specimens covered by the Ni aluminide layer containing the ZrAl_3 and HfAl_3 particles was evaluated in air at 1423K. The sample covered with the Ni aluminide containing the ZrAl_3 and HfAl_3 particles, which was formed using the melt containing 3.5mol%AlF_3-0.05mol%HfF_4 and 3.5 mol%AlF_3-0.05mol%HfF_4, showed a high cyclic-oxidation resistance. On this sample after the oxidation test, an adhesive scale having a spiked shape, which consisted of Al_2O_3 as the outer layer and ZrO_2 or HfO_2 as the inner layer, was formed.