Abstract
The microstructure of newly developed hard magnetic Fe42Ni41.3SixB12-xP4Cu0.7 (x = 2 to 8 at%) nanocrystalline alloy ribbons has been studied by transmission electron microscopy (TEM) and electron diffraction. A high-density polycrystalline grains, ∼30 nm in size, were formed in a ribbon after annealing at 673 K for 288 hours. Elemental mapping of the annealed specimen revealed the coexistence of three regions, Fe-rich, Ni-rich, and nearly equiatomic Fe-Ni, with areal fractions of 37%, 40%, and 23 %, respectively. The equiatomic L10-type ordered phase of FeNi was detected in between the Fe and Ni-rich phases. The presence of superlattice reflections in nanobeam electron diffraction patterns confirmed the formation of the hard magnetic L10 phase beyond any doubt. The L10 phase of FeNi was detected in alloys annealed in the temperature range of 673 to 813 K. The present results suggest that the order-disorder transition temperature of L10 FeNi is higher than the previously reported value (593 K). The high diffusion rates of the constituent elements induced by the crystallization of an amorphous phase at relatively low temperature (∼673K) are responsible for the development of atomic ordering in FeNi.
Highlights
The remarkable growth in automobile technologies in recent years demands development of low cost high performance magnets, which are free from rare-earth or noble metals
The purpose of this study is to reveal the microstructure of newly developed hard magnetic Fe42Ni41.3SixB12-xP4Cu0.7 (x = 2 to 8 at%) nanocrystalline alloys produced by crystallization of melt-spun amorphous ribbons using transmission electron microscopy (TEM) and electron diffraction
The intensity profile exhibits a large number of well-defined peaks/reflections, which can be indexed by three phases: body-centered cubic, orthorhombic phase (Fe3B), face-centered cubic, and ordered L10 FeNi
Summary
The remarkable growth in automobile technologies in recent years demands development of low cost high performance magnets, which are free from rare-earth or noble metals. A brief history of the investigation on tetrataenite has been reviewed in the literature.[10,12] the production of the ordered phase is practically difficult since the order-disorder transition temperature of this alloy was reported to be as low as 593 K.2 Mobility of atoms is extremely low below the transition temperature
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
