Evaluating the effect of Mn composition on chemical partitioning in Co(78−x)Fe2MnxB14Si2Nb4 magnetic amorphous nanocomposites

Influence of Mn Doping on Local Spin Moments and Stacking Fault Energies in Co(Mn) Alloys

“…The opposite behavior, however, is expected for nanocrystalline Co, which is predicted to undergo deformation via phase transformation from HCP to FCC, as the energy required for a phase transformation is lower than that required to generate twins [15]. Consequently, as the Co 78−x Fe 2 Mn x B 1 4Si 2 Nb 4 alloys have been shown to possess very small grains of the order of only a few nanometers [7], this work will focus on understanding stacking fault behavior in Co and Mn-doped Co in the FCC phase. It should be noted that Mn dopants in FCC Fe are reported by Limmer et al to stabilize the local HCP phase [16], so there is potential for a similar behavior to arise in our calculations.…”

“…Advanced soft magnetic materials used in motors, transformers, and filter inductors can enable low-carbon-footprint transportation systems [1][2][3][4][5]. Of interest for this work, among others, are complex metal-amorphous nanocomposite Co-based alloys that include other constituent elements, such as Fe, Mn, B, Si, and Nb [6][7][8]. The alloys begin as an amorphous ribbon, which is annealed to produce fine nanocrystallites embedded within an amorphous matrix.…”

“…An initial analysis of Co 78−x Fe 2 Mn x B 1 4Si 2 Nb 4 alloys, where 0.5 ≤ x ≤ 6, via transmission electron microscopy and ferromagnetic resonance showed evidence that the nanocrystallites were formed in both the hexagonal close-packed (HCP) and face-centered cubic (FCC) crystallographic phases [6], despite the tendency of bulk Co to be stable in the HCP phase at room temperature [10]. Further experimental work with this type of material has focused on certain magnetic and crystallographic behaviors, particularly as concentrations of the alloying elements change [6][7][8]. This work will focus on the theoretical analysis of the structural behavior of the Co-rich nanocrystallites.…”

“…This work will focus on the theoretical analysis of the structural behavior of the Co-rich nanocrystallites. As many of the constituent elements remain in the amorphous phase and are not part of the nanocrystallite system, specific attention will be paid to a Co 1−x Mn x binary alloy system to determine the influence, if any, of Mn doping on the stability of the two primary crystallographic phases of Co. We have chosen to focus on Mn as the dopant due to experimental observations made by Koenig et al [7] and Nakarmi et al [8]. Additionally, the magnetic behavior of Mn as a dopant in Co is sensitive to composition, as noted by Stepanyuk et al [11].…”