ВЛИЯНИЕ ПЛАСТИЧЕСКОЙ ДЕФОРМАЦИИ TiNi ПРОВОЛОКИ НА ТЕРМОКИНЕТИЧЕСКУЮ ЭДС

Abstract

The initiation of thermokinetic EMF in titanium nickelide alloys is possible when shifting both the heating zone along the extended TiNi sample and the locally cooled zone. In this case, heating in the conductor local zone causes the reverse phase transformation (T≥As), and cooling causes the direct phase transformation (T≤Ms). Previously, it was experimentally proved that the value of induced EMF increases when shifting the cooling zone through the locally deformed area, and the EMF increase depends on the deformation of TiNi sample. It should be noted that the physical nature of this phenomenon is not entirely investigated. The paper suggests a physical model, according to which the thermokinetic EMF is initiated in the result of the difference of potentials in the areas with direct and reverse phase transformations occurring when shifting the cooling zones along TiNi alloy. When the cooling area passes the deformed zone, the EMF, caused both by the difference of thermo-EMF ratios of the deformed and non-deformed areas of TiNi sample and thermal effect, arises at the boundaries of deformation zones. Mathematical expressions allowing the calculation of thermokinetic EMF value change when passing a plastically deformed area were obtained. These expressions prove that thermokinetic EMF increases with the plastic deformation increase (the length of the deformed area is 6 cm). The results of calculation of thermokinetic EMF change, when the cooling zone passes through the deformation zone in the TiNi alloys, fit the experimental data and can be used when developing methods of control of the extended TiNi products’ homogeneity.