Annealing behaviour of amorphous Fe80B20 on continuous heating |
| |
Authors: | O T Inal C V Robino L Keller F G Yost M M Karnowsky |
| |
Affiliation: | (1) Department of Metallurgical and Materials Engineering, New Mexico Institute of Mining and Technology, 87801 Socorro, New Mexico, USA;(2) Sandia National Laboratories, 87185 Albuquerque, New Mexico, USA |
| |
Abstract: | Resistance measurements during direct heating of Fe80B20 amorphous alloys indicate phase changes occur at 395, 500, 720 and 840° C. Samples heated to these temperatures, and maintained for five minutes in a neutral atmosphere, show that a hardness maximum occurs at the crystallization temperature of 395° C and that annealing at 500° C produces a material with the same hardness. Above 500° C the microhardness is seen to drop below that of the amorphous alloy. Saturation magnetization measurements show a steady increase following each anneal, up to a temperature of 720° C, and the rate of increase is seen to drop in the range of 720 to 840° C. X-ray diffraction studies show that only a small fraction of the matrix is crystallized following the anneal at 395° C and the transformed phases are -Fe and Fe3B. Following annealing at 500° C, an increased proportion of -Fe and Fe3B are observed with complete crystallinity while samples heattreated at 720° C are seen to consist of a three-phase mixture of -Fe, Fe23B6 and Fe2B. Annealing at 840° C is seen to produce an equilibrium phase mixture of -Fe and Fe2B phases. Only in the sample annealed at 395° C is a fraction of the amorphous phase seen to persist, indicating that a 5 min anneal is not sufficient, at this temperature, to induce complete crystallization. These structural features are corroborated by field ion microscope analyses, made at liquid nitrogen temperature in a medium of pure neon, and scanning electron microscopy, and are also consistent with our earlier study involving the isothermal annealing, for various times, of Fe80B20 alloy at 780° C. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|