Viscous Phenomena in Magnetic and Thermal Properties of Fe-Ni-Based Glasses Induced by Cryo-Treatments

The influence of cryo-treatment is investigated according to some magnetic and thermal properties of Fe₄₀Ni₄₀Si₆B₁₄ glassy alloy. Saturation magnetization (M_S), amorphous Curie temperature (T_C ^am) heat capacity (C_p) and the width of crystallization exotherm peak were measured before and after the cryo-treatment. The treatment causes a very stable structural imprint in the investigated properties. Not all property changes are completely irreversible, however. The T_C ^am exhibits a very slow, viscous reconstruction during subsequent isothermal or cyclic heat treatments. The heat capacity of cryo-treated samples increases compared to the nontreated ones. Due to the low temperature treatment the kinetic of crystallization changes also, which is manifested in the shift of half width of crystallization peak. The magnitude of the LN treatment induced effects depends on the whole thermal history of the sample.