THERMOKINETIC EFM IN NIKELIDE TITANIUM DURING REVERSE PHASE TRANSFORMATION

Thermokinetic EMF in the Ti-50at.% Ni alloy has been investigated. It is showed that the movement of the heating zone in the wire samples causes thermokinetic EMF of about 0.22 mV, which is constant in magnitude and direction. The change in the movement of the heating zone causes the change in polarity of thermokinetic EMF due to the thermoelastic phase transformations in the heating zone and the contact potential difference between the regions of the TiNi material which are in different phase states. The temperature cycling of the sample leads to a decrease in thermokinetic EMF value upon unsteady heating. EMF value is reduced to 0mV after 70 thermal cycles due to the change in characteristic temperatures and the formation of R-phase which has higher electrical resistance. It is known that with increased temperature up to 240°C in the heating zone of the sample during thermal cycling makes it possible to restore thermokinetic EMF value to a maximum of 0.22 mV. Different thermokinetic EMF values along elongated TiNi products can be purposely set for the sample which is subjected to different thermal effects during thermal cycling.