Trapping stiffness measurement with brownian motion analysis method at low sampling frequency

The Fe61Co7Zr9.5Mo5W2B15.5 bulk metallic glass (BMG) has the best glass forming-ability (GFA), high thermal stability, and the highest strength (the compressive strength sigma = 3800 MPa) among known Fe-based alloys. Unfortunately, this BMG does not have the same good soft magnetic properties as other Fe-based BMGs do. We report here that a small amount of Ni addition (microalloying) can significantly enhance the soft magnetic properties of the alloy without deteriorating its high GFA. The saturation magnetization is increased threefold, while the coercivity is decreased about 40-fold, with only 3 at.% Ni addition. The improvement is interpreted to result from the enhancement of the magnetic exchange interaction as the Ni content increases. The results indicate that it is possible to adjust the magnetic properties of Fe-based BMGs by a minor change in the content of some component. BMGs with good soft magnetic property, ultrahigh mechanical strength, good GFA and high thermal stability show some promise for future applications.