Magnetostrictive loss reduction through stress relief annealing in an FeNi-based metal amorphous nanocomposite

• Published in: Journal of materials research Vol. 36; no. 14
• Main Authors: Byerly, Kevin, Krimer, Yuval, Phatak, Charudatta, Theisen, Eric, McHenry, Michael E.
• Format: Journal Article
• Language: English
• Published: United States Materials Research Society 22-06-2021
• Subjects: Amorphous; Annealing; Crystallization; Magnetic properties; MATERIALS SCIENCE
• ISSN: 0884-2914; 2044-5326

FeNi-based metal amorphous nanocomposite alloys are emerging soft magnetic materials with promise for high-speed motor applications. Here we demonstrate a technique to optimize magnetic properties in toroidal cores wound from strain annealed (Fe70Ni30)80Nb4Si2B14 amorphous metal ribbon (AMR). In-line strain annealing (SA) of the AMR yields a strip permeability that monotonically decreases with increasing SA tensions. After winding into toroidal cores, dramatic changes in magnetic properties are observed and determined to be of magnetostrictive origin. A procedure to re-anneal wound toroidal cores to reduce hysteresis and reverse magnetostrictive effects is developed inclusive of casting curvature effects. Here, we investigate re-annealing temperatures between 300 – 470 °C for cores produced from each SA condition. Magnetic core loss, WL, coercivity, Hc, squareness ratio, Kr, and permeability, µr, are measured as a function of (stress relief) re-annealing temperature to optimally achieve W1T,400Hz = 0.51 W/kg, Hc = 2.42 A/m, Kr = 0.22, and µr = 35,300.