Response of structural and magnetic properties of ultra-thin FeCo–V foils to high-energy beam welding processes

Abstract

Microstructural evolutions and grain-boundary-character distribution during high-energy-beam welding of ultra-thin FeCo-V foils were studied. Detailed data about the boundaries, coincidence site lattice (CSL) relationships, grain sizes, and microstructural features were acquired from electron-backscatter diffraction (EBSD) maps. Moreover, the evolution of the magnetic properties during high-energy-beam welding was studied using vibrating sample magnetometry (VSM). The fraction of low-angle boundaries was observed to increase in the fusion zones of both electron- and laser-beam-welded foils. The results showed that the fractions of low-Ʃ CSL boundaries (particularly twin boundaries, Ʃ3) in the fusion zones of the welded foils are higher than those in the base metal. Because the strain rates produced during high-energy-beam welding are very high (because of the extremely high cooling rate), grain deformation by a slip mechanism is limited; therefore, deformation by grain twinning is dominant. VSM analysis showed that the magnetic properties of the welded foils, i.e., their remanence, coercive force, and energy product, changed significantly. The formation of large grains with preferred orientation parallel to the easy axis of magnetization was the main reason for the diminished magnetic properties.

Keywords

iron cobalt vanadium alloys / thin foils / electron beam welding / laser beam welding / magnetic materials

References

[1] Major R.V., Samadian V. Physical metallurgy and properties of a new high saturation Co-Fe alloy. J. Mater. Eng., 1989, 11(1): 27.

[2] M.S. Lucas, J.A. Munõz, L. Mauger, C.W. Li, A.O. Sheets, Z. Turgut, J. Horwath, D.L. Abernathy, M.B. Stone, O. Delaire, Y.M. Xiao, and B. Fultz, Effects of chemical composition and B2 order on phonons in bcc Fe–Co alloys, J. Appl. Phys., 108(2010), art. No. 023519.

[3] Sourmail T. Evolution of strength and coercivity during annealing of FeCo based alloys Scripta Mater., 2004, 51(6): 589.

[4] Gilles R., Hofmann M., Johnson F., Gao Y., Mukherji D., Hugenschmidt C., Pikart P. Analysis of antiphase domain growth in ternary FeCo alloys after different cooling rates and annealing treatments using neutron diffraction and positron annihilation. J. Alloys Compd., 2011, 509(2): 195.

[5] Lucas M.S., Bourne W.C., Sheets A.O., Brunke L., Alexander M.D., Shank J.M., Michel E., Semiatin S.L., Horwath J., Turgut Z. Nanocrystalline Hf and Ta containing FeCo based alloys for high frequency applications. Mater. Sci. Eng. B, 2011, 176(14): 1079.

[6] Liu S., Bauser S., Turgut Z., Coate J., Fingers R.T. Fe–Co–V alloy with improved magnetic properties and high-temperature creep resistance. J. Appl. Phys., 2003, 93(10): 7118.

[7] Díaz-Ortiz A., Drautz R., Fähnle M., Dosch H., Sanchez J.M. Structure and magnetism in bcc-based iron-cobalt alloys. Phys. Rev. B, 2006, 73(22): 224208.

[8] Wu L.Z., Chen J., Du Z.Z., Wang J.T. Microstructures of ultra-fine grained FeCoV alloys processed by ECAP plus cold rolling and their evolutions during tempering. Trans. Nonferrous Met. Soc. China, 2010, 20(4): 602.

[9] Couto A.A., Ferreira P.I. Phase Transformations and Properties of Fe-Co Alloys. J. Mater. Eng., 1989, 11(1): 31.

[10] Zhu F.Z., Bi X.F., Zhang S.Q., Gong S.K., Xu H.B. Phase transformation and magnetic properties of annealed Fe52.2Co46V1.8 alloy. Vacuum, 2004, 75(1): 33.

[11] Kawahara K. Effect of additive elements on cold workability in FeCo alloys. J. Mater. Sci., 1983, 18(6): 1709.

[12] Sundar R.S., Deevi S.C. Effect of heat-treatment on the room temperature ductility of an ordered intermetallic Fe–Co–V alloy. Mater. Sci. Eng. A, 2004, 369(1–2): 164.

[13] Zakharov V.M., Libman M.A., Estrin E.I. On the role of atomic ordering in the formation of a high-coercivity state in iron-cobalt-vanadium alloys. Phys. Met. Metallogr., 2012, 113(1): 43.

[14] Laughton M.A., Warne D.J. Electrical Engineer’s Reference Book, 2002

[15] Sundar R.S., Deevi S.C. Soft magnetic FeCo alloys: alloy development, processing, and properties. Int. Mater. Rev., 2005, 50(3): 157.

[16] Callister ffixJr W.D. Fundamentals of Materials Science and Engineering, 2001, USA, John Wiley & Sons Inc

[17] Chen W., Molian P. Dual-beam laser welding of ultra-thin AA 5052-H19 aluminum. Int. J. Adv. Manuf. Technol., 2008, 39(9–10): 889.

[18] Li X.Z., Hu S.B., Xiao J.Z., Ji L.B. Effects of the heterogeneity in the electron beam welded joint on fatigue crack growth in Ti–6Al–4V alloy. Mater. Sci. Eng. A, 2011, 529, 170.

[19] Yang S., Wang Z.J., Kokawa H., Sato Y.S. Grain boundary engineering of 304 austenitic stainless steel by laser surface melting and annealing. J. Mater. Sci., 2007, 42(3): 847.

[20] Hasani S., Shamanian M., Shafyei A., Behjati P., Szpunar J.A., Fathi-Moghaddam M. Nano/sub-micron crystallization of Fe–Co–7.15V alloy by thermo-mechanical process to improve magnetic properties. Mater. Sci. Eng. B, 2014, 190, 96.

[21] Kou S. Welding Metallurgy, 2003

[22] Akbari Mousavi S.A.A., Niknejad S.T. An Investigation on microstructure and mechanical properties of Nd:YAG laser beam weld of copper beryllium alloy. Metall. Mater. Trans. A, 2009, 40(6): 1469.

[23] Ventrella V.A., Berretta J.R., de Rossi W. Micro Welding of Ni-based Alloy Monel 400 Thin Foil by Pulsed Nd:YAG laser. Phys. Procedia, 2011, 12, 347.

[24] Ventrella V.A., Berretta J.R., de Rossi W. Pulsed Nd:YAG laser seam welding of AISI 316L stainless steel thin foils. J. Mater. Process. Technol., 2010, 210(14): 1838.

[25] Han K., Hirth J.P., Embury J.D. Modeling the formation of twins and stacking faults in the ag-cu system. Acta Mater., 2001, 49(9): 1537.

[26] Baudin T., Etter A.L., Penelle R. Annealing twin formation and recrystallization study of cold-drawn copper wires from EBSD measurements. Mater. Charact., 2007, 58(10): 947.

[27] Badji R., Chauveau T., Bacroix B. Texture, misorientation and mechanical anisotropy in a deformed dual phase stainless steel weld joint. Mater. Sci. Eng. A, 2013, 575, 94.

[28] Chen X.Z., Wang J.J., Fang Y.Y., Madigan B., Xu G.F., Zhou J.Z. Investigation of microstructures and residual stresses in laser peened Incoloy 800H weldments. Opt. Laser Technol., 2014, 557, 159.

[29] Yu R.H., Basu S., Zhang Y., Parvizi-Majidi A., Xiao J.Q. Pinning effect of the grain boundaries on magnetic domain wall in FeCo-based magnetic alloys. J. Appl. Phys., 1999, 85(9): 6655.

[30] Yu R.H., Basu S., Zhang Y., Xiao J.Q. Magnetic domains and coercivity in FeCo soft magnetic alloys. J. Appl. Phys., 1999, 85, 6034.

[31] Porter D.A., Easterling K.E., Sherif M.Y. Phase Transformation in Metals and Alloys, 2009 3 New york, CRC Press

[32] Hall R.C. Magnetic Anisotropy and magnetostriction of ordered and disordered cobalt-iron alloys. J. Appl. Phys., 1960, 31, S157.