Thermally and pressure activated phase evolution in Fe–Pt–Nb–B melt spun ribbons

✍ Scribed by A.D. Crisan; R. Nicula; O. Crisan; E. Burkel

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 245 KB
• Volume: 27
• Category: Article
• ISSN: 0928-4931
• DOI: 10.1016/j.msec.2006.06.033

✦ Synopsis

The Fe-Pt-rich alloys has recently attracted a lot of interest for their potential development of the hard magnetic L1 0 (also denoted γ 1 ) FePt phase with high magnetocrystalline anisotropy. An alloy with the nominal composition Fe 65 Pt 25 Nb 2 B 8 has been synthesised by rapid quenching of the melt. The phase evolution in the as-cast ribbons was monitored by energy dispersive X-ray diffraction of the synchrotron radiation. It is shown that the Fe 65 Pt 25 Nb 2 B 8 alloy is completely crystallized in the as-cast state. With increasing temperature a partial disorder-order phase transformation with occurrence of hard magnetic L1 0 phase is observed. This transformation is directly related to thermal and pressure effects in the sample. With applying pressure, the phase transformation between cubic and tetragonal FePt symmetry is more pronounced and is accompanied by a strong uniaxial lattice expansion. The results are extremely promising for the direct formation from the melt of an exchange coupled hard-soft magnetic alloy with initial formation of the tetragonal hard magnetic L1 0 FePt phase.