HEATING RATE DEPENDENCE OF 2 GLASS TRANSITIONS AND PHASE-SEPARATION FOR A LA55AL25NI20 AMORPHOUS ALLOY

The heating rate dependence of two relaxation systems for two glass transitions for a La55Al25Ni20 amorphous alloy was examined through the changes in storage, E', and loss, E'', moduli. The appearance of the higher temperature relaxation in E'(T) shifts to higher temperatures with increasing heating rate. The higher temperature relaxation peak in E''(T) shifts to higher temperatures though the lower temperature peak slightly shifts to lower temperatures with increasing heating rate. Under the transmission electron microscopic observation. the amorphous phase shows a phase separation during heating. The effect of the heating rate on the phase separation causes the change in E'(T) and E''(T) behavior with the heating rate. The glass transition temperature obtained by calorimetric measurement also shifts to higher temperatures with increasing heating rate reflected by the higher temperature relaxation.