铁磁应变玻璃及其物理特性

Ferromagnetic strain glass is a glassy phenomenon reported in the defects of doped Ni-Mn-Ga, Fe-Pd, and Fe-Ni-Cr ferromagnetic martensitic alloy systems recently. It is essentially a frozen state with coexisting short-range lattice strain order and long-range magnetic order. The basic structural unit of the ferromagnetic strain glass is the magnetic martensitic nanodomain. The reorientation energy barrier of these nanodomains is insignificant. They grow slowly across a wide temperature region in the parent phase matrix, and the modulus of the parent phase matrix and nanodomains shows an opposite temperature-dependent tendency. These transforming properties lead to the low-field-driven large magnetostriction and Elinvar effect. Therefore, ferromagnetic strain glass alloys have potentially important applications in microactuators or sensors and precision apparatuses. This paper introduces the macroscopic physical properties, microstructural characteristics, and functional effects of ferromagnetic strain glass. Through the phase diagram of the NiX-Mn-Ga (X=Co, Fe) system, the formation of a ferromagnetic strain glass and its relationship with martensitic and premartensitic phases are clarified. Furthermore, the novel transformation behavior, i.e., the spontaneous martensitic transition of ferromagnetic strain glass in the phase boundary region between ferromagnetic martensite and ferromagnetic strain glass, is also introduced. The material design based on ferromagnetic strain glass is expected to bring new opportunities for the performance breakthrough and functionality development of magnetic materials.