Effect of the linewidth reduction on the characteristic time spread in C49-C54 phase transition

The kinetics of the C49-C54 phase transformation in TiSi2 narrow strips for width in the 0.5-1.3 mm range was investigated by sheet resistance measure ments. The experimental data follow the Johnson-Mehl-Avrami equation for th e fraction of the transformed material, with an exponent equal to 1 for all of the analyzed linewidths. Nucleation sites saturation occurs and the gro wth is one-dimensional along the length of the strip. The characteristic ti me, as obtained by the fit, increases as 1/W, W being the width of the stri p, and a nucleation density of about 0.05 sites/mu m(2) has been obtained. The distribution of the characteristic times around the average value incre ases with decreasing the linewidth. The amplitude of the dispersion is in q uantitative agreement with the statistical fluctuation of the number of nuc leation sites. (C) 1998 American Institute of Physics. [S0003-6951(98)04152 -7].