Volume 7, Issue 2 (February 2010)
Low-Temperature Thermo-Cycling of FINEMET and Metglas Amorphous Alloys: Last Achievements in Theory and Experiments
The novel phenomena of irreversible changes in structure and main physical properties of FINEMET and Metglas amorphous metallic alloys (AMA) after low-temperature treatment (LTT) (so called ΔT effect) are studied theoretically and experimentally. It is shown theoretically that the cooling process in AMA during LTT is achieved at a rate comparable to the rate of quenching from the melt. Arising thermo-elastic stresses cause changes in the structure of the short-range order due to the drift of metalloid atoms, which is supported by sample oscillations with the eigenfrequencies. Such homogenization of the AMA structure leads to changes in the main physical properties. The proposed physical model of the ΔT effect is verified by structural investigations and magnetic and thermo-magnetic studies of metal-metalloid and FINEMET type AMA.