A method for enlarging the active surface area of alloy materials in which intermetallic compounds are uniformly dispersed

摘要

PURPOSE:To increase the exposed face of an intermetallic compound in an alloy foil which is used as an electrode for electrolytic capacitor use and to expand an effective surface area by a method wherein an alloy material in which the intermetallic compound has been dispersed and precipitated uniformly is electrolyzed in a nonaqueous solvent-based electrolyte by making use of the metal material as an electrode. CONSTITUTION:An alloy material 1 in which an intermetallic compound 4 has been dispersed and precipitated uniformly is electrolyzed in a nonaqueous solvent-based electrolyte by making use of the metal material 1 as an anode, a metal matrix 2 is etched selectively, and the surface of the intermetallic compound 4 is exposed. Alternatively, the alloy material 1 in which the intermetallic compound 4 has been dispersed and precipitated uniformly is treated in the nonaqueous solvent-based electrolyte, the metal matrix 2 in the peripheral part of the intermetallic compound 4 is etched, an electrolytic treatment is executed by using the nonaqueous solvent-based electrolyte, and the active surface of the intermetallic compound 4 is exposed. For example, an Al-based alloy or the like in which one or more kinds out of Ti, Zr, Ta, Hf, Si, Zn, Nb, Bi, Mg and the like have been added to Al is used for said alloy material 1.