Characteristics of TiNi Shape Memory Foils Fabricated by Double Cathodes Electrochemical Polishing

Ti₅₀Ni₅₀ shape memory foil with 25 μm in thickness and having two smooth surfaces can be fabricated by an electrochemical polishing technique. This technique, using double cathode plates, may shorten the polishing time and alleviate the over-etched pitting effect. The grains on the surface of the hot-rolled sheet are elongated along the rolling direction, and those in the center of the electrochemically polished foil are equal-axial with an average grain size of approximately 8.5 μm. Both transformation temperature and enthalpy of the electrochemically polished foils decrease with the decreasing specimen’s thickness. The fabricated Ti₅₀Ni₅₀ foils possess the advantages of a more uniform chemical composition throughout the specimen, larger grain size, larger foil area, and greater thickness than those of sputtered TiNi thin films and melt-spun TiNi ribbons.