NMR and Mössbauer study of peculiarities of the structure formation in Fe–Сo alloys

• Published in: Physics of metals and metallography 2017-11, Vol.118 (11), p.1040-1047
• Main Authors: Serikov, V. V., Kleinerman, N. M., Golovnya, O. A.
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Cobalt; Electrical and Magnetic Properties; Ferrous alloys; Hyperfine structure; Magnetic moments; Materials Science; Metallic Materials; NMR; Nuclear magnetic resonance; Phase separation; Short range order
• ISSN: 0031-918X; 1555-6190
• DOI: 10.1134/S0031918X1711014X

Fe–Co alloys with an Fe content of 20–95 at % have been investigated using NMR and Mössbauer spectroscopy. A comparison of the hyperfine fields measured at 59 Со and 57 Fe nuclei on the same samples allowed us to determine that the magnetic moment at an Fe atom in the disordered alloys with Fe concentrations of 20–80 at % varies from 2.8 to 2.4 μ B , as well as to ascertain peculiarities of the formation of an ordered state. The data obtained indicate the existence of regions with a short-range order of the D 0 3 type in alloys with an Fe content of 70–80 at %. In alloys with iron concentrations greater that 80 at %, the phase separation of the structure into regions of elemental iron and short-range-ordered Fe 89 Co 11 regions is observed. The obtained results explain the contradictions in the values of the magnetic moment at the Fe atom and the anomalous dependence of the lattice parameter of the alloy with a Со content less than 20 at %, as well as prove the accuracy of the phase diagram containing regions of three bcc phases, rather than one, as is commonly accepted.