Prediction of good glass forming ability in amorphous soft magnetic alloys by thermocalc simulation with experimental validation

Alloys in a (Fe70Ni30)(80)(B-Si-Nb)(20) system, with good glass forming ability (GFA), were identified using Thermocalc software to simulate liquidus temperatures (T's) and solidification ranges (areas between the liquidus and solidus in a binary phase diagram,a line at fixed T). A region with excellent GFA was identified at 14-18% B and 0-7% Si with the balance Nb, showing minima in liquidus and solidification range. A region with a solidification range minimum, but no corresponding liquidus minimum was identified at 3-8% B and 5-10% Si but had lower GFA. A shallow liquidus minimum, with no minimum in solidification range, at 3-5% B and 1-3% Si had the lowest GFA and did not produce amorphous material. Measured GFA was ranked using parameters T-rg, Delta T-xg, and gamma(m), defined herein. Only the reduced glass transition temperature, T-rg, was predictive for the alloys. Differential Scanning Calorimetry (DSC) data showed liquidus T's to agree. Curie temperatures, T-c's were observed to increase with B/Nb ratio. Simulations of liquidus and solidification range for alloys with 18 and 15% glass formers do not show regions with minima in both, indicating good GFA is not expected. (C) 2019 Elsevier B.V. All rights reserved.