ANALYSIS OF THERMAL CYCLING STABILITY FOR A TiNi TWO-WAY SHAPE MEMORY ALLOY BY POSITRON ANNIHILATION SPECTROSCOPY

The S-lineshape measurements of Doppler-broadening of positron annihilation, which are strongly dependent on thermal cycling time, were performed for a Ti-51at.-%Ni alloy having two-way shape memory effect. As the S-parameter increased to about 80% of the maximum value, the property of the two-way shape memory effect in the alloy may be stabilized. Both microscopic and macroscopic measurements are identical. This result seems to be available not only for establishing an effective and convenient method to analyze the stability of two-way shape memory effect, but also for evaluating such microscopic positron annihilation spectroscopy as a measure of metallic material research.