Soft magnetic FeCo alloys: alloy development, processing, and properties

TLDR

FeCo intermetallic alloys combine high saturation magnetisation, high Curie temperature, low magnetocrystalline anisotropy, and good strength, making them ideal for high‑flux applications, but their high cost limits widespread use, prompting renewed interest in high‑temperature soft magnetic materials. This review summarizes phase transformations, processing, mechanical, magnetic and electrical properties of binary, ternary and complex FeCo alloys, and highlights research areas needed to elucidate alloying and processing effects on high‑temperature mechanical, electrical, and magnetic properties. Earlier studies are summarized with emphasis on phase transformations, processing, mechanical, magnetic and electrical properties of FeCo alloys, and current interest in nanocrystalline and thin‑film FeCo compositions is also reviewed.

Abstract

FeCo intermetallic alloys are well known to possess a unique combination of high saturation magnetisation, high Curie temperature, low magnetocrystalline anisotropy and good strength. They are ideally suited for applications requiring high flux densities. Intense research and development efforts over the years resulted in significant improvements in mechanical properties and better understanding of phase transformations in FeCo alloys. However, the high cost of the alloys has prevented their widespread applications. Emerging needs for soft magnetic materials to operate at high temperatures have caused renewed interest in FeCo alloys. The earlier studies are summarised in this review with special emphasis on phase transformations, processing, mechanical, magnetic and electrical properties of binary, ternary and more complex FeCo alloys. Current interest in developing nanocrystalline and thin films based on FeCo compositions is also summarised. The research areas that need to be addressed are also emphasised to clearly elucidate the effects of alloying additions and processing on the electrical and magnetic properties and on the high temperature mechanical properties of these alloys.