Mechanism of Formation of the High-Coercivity State in Nanostructured Hard Magnetic Fe-Cr-Co and Fe-Ni-Al-Co-Cu Alloys

摘要

The leading process that controls all other processes that form the high-coercivity state in Fe-Cr-Co and Fe-Ni-Al-Co-Cu alloys is assumed to be ordering in either a high-coercivity Fe-Co phase or a low-coer-civity Ni-Al matrix. This ordering proceeds as a first-order phase transformation, which requires a certain degree of supercooling and, thus, a critical cooling rate. The requirement of cooling of precipitation-hardening hard magnetic Fe-Cr-Co and Fe-Ni-Al-Co-Cu alloys at a critical rate in various temperature ranges for both thermomagnetic treatment and the final stages of aging in order to obtain the optimum magnetic hysteretic properties, which is well known from the practice of heat treatment of these alloys, has not yet been grounded in spite of the fact that these alloys have been studied for several decades.