Effect of Cooling Rate on the Transformation Temperatures of Ni₅₀Ti₃₆Hf₁₄ Melt-Spun Ribbons

Abstract

Solidification structures and shape memory characteristics of Ni50Ti36Hf14(at.%) alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the velocity of cooling wheel from 20 to 40 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate on solidification structures and martensitic transformation behaviors is discussed. When the ribbon is produced at a wheel velocity of 40 m/s in melt spinning, the degree of supercooling becomes high because of its thinner thickness.