Magnetostrictive Iron-Based Bulk Metallic Glasses for Force Sensors

Iron-based bulk metallic glasses have been known for several attractive properties, such as high mechanical strength and magnetic softness. They also exhibit sensitivity of magnetic properties to stress, which is the result of magnetoelastic coupling. In this paper, these combined features were exploited to build a simple, but effective magnetoelastic force sensor. It was found that when rods made of glassy (Fe,Co,Ni)-Nb-Si-B alloys, used as cores in a transformer, are subjected to compressive stress, voltage on secondary winding changes with the application of force. When proper measurement conditions are met, the dependence of output voltage versus force is nearly linear. Furthermore, rods with 2 mm in diameter are able to withstand forces reaching 8 kN, which gives an opportunity to design small-sized, high-load magnetoelastic force sensors.