Influence of melt temperature on the Invar effect in (Fe71.2B24Y4.8)96Nb4 bulk metallic glass

• DOI: 10.1007/s10853-014-8392-z
• Publication Date: 2014-06-27T13:24:20Z
• Authors: Q. Hu; H. C. Sheng; M. W. Fu; X. R. Zeng
• Keywords: Invar; Atmospheric temperature range

The influence of melt temperature on the glass formation, physical properties and local structure of (Fe71.2B24Y4.8)96Nb4 bulk metallic glass (BMG) was investigated through X-ray diffractometry, differential scanning calorimetry, thermal dilatation, and Mossbauer spectra tests. Amorphous alloys were formed by fast cooling of the melt from the temperature range of 1573–1773 K. BMG cast from 1623 K has lower Curie temperature and larger spontaneous volume magnetostriction, i.e., stronger Invar effect. The abnormality, which can not be eliminated by annealing, is attributed to the higher amount of Fe–Fe pairs indicated by the hyperfine field distribution. This special local structure is inherited from the melt, which has a liquid–liquid change manifested by an exothermic step region at the temperature range of 1615–1650 K. Through a slow-cooling process, the melt in the liquid–liquid change is frozen to a crystalline structure contained Y2Fe17 phase with a high intensity signal. These findings help explain the correlation between the liquid–liquid change and the structure of cooling products.