Magnetic properties of amorphous and nanocrystalline Fe−Ni−Mo−B alloys

Andrejco, R.; Varga, R.; Marko, P.; Vojtaník, P.

doi:10.1007/s10582-002-0026-z

Cited by 3 publications

(5 citation statements)

References 6 publications

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“…10 One can see that the values of minimum switching field H sw was reached at T a = 620 K / 1 h. Annealing above 620 K, the crystalline ␥-͑Fe, Ni͒ phase appears. In the case of nanocrystalline materials, the coercivity depends on the exchange interaction of the crystalline grains.…”

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confidence: 91%

“…Moreover, the saturation magnetostriction of FeNiMoB alloys increases by annealing at higher than optimal temperature. 10,11 Hence, the magnetoelastic anisotropy increases and the switching field does the same too.…”

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confidence: 98%

“…9 Annealing of such samples at T a = 700 K has been shown to be the optimum annealing temperature to obtain nanocrystalline Fe 40 Ni 38 Mo 4 B 16 alloy with optimized soft magnetic properties ͑lowest magnetostriction, lowest coercive field, and highest initial susceptibility͒. 10,11 Since ␥-͑Fe, Ni͒ phase is ferromagnetic contrary to the paramagnetic ␥-Fe phase, it is a promising candidate for preparation of soft magnetic nanocrystalline microwires. We demonstrate that Fe 40 Ni 38 Mo 4 B 16 alloy composition can be considered to prepare soft magnetic nanocrystalline microwires with positive magnetostriction.…”

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confidence: 99%

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Nanocrystalline glass-coated FeNiMoB microwires

Komova

Varga

et al. 2008

Applied Physics Letters

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The evolution of the structure of glass-coated Fe 40 Ni 38 Mo 4 B 16 amorphous microwire with thermal treatments and its interplay with magnetism has been studied. As shown by x-ray diffraction, a primary crystallization process resulted into formation of ␥-͑Fe, Ni͒ nanocrystallites embedded in a residual amorphous matrix. The evolution of the saturation magnetization and the switching field after different thermal treatment was studied. Amorphous glass-coated microwires based on FeNi exhibit magnetic bistability even in the nanocrystalline state. This is explained by the high magnetoelastic anisotropy, which is also responsible for magnetic hardening after annealing at the temperatures above 670 K. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2969057͔Amorphous and nanocrystalline ferromagnetic microwires covered by a glass coating are very attractive material for applications, mainly as sensing elements in various sensors ͑i.e., magnetic field, coding, etc.͒, due to their outstanding magnetic characteristics, small dimensions and reliability on electrical, mechanical, and corrosive external effects ͑as a result of the Pyrex coating͒.1 These microwires, prepared by quenching and drawing technique, consist of a magnetic nucleus ͑with diameter from 1 -30 m͒ coated by a Pyrexlike glass ͑thickness of 2 -20 m͒. Due to their amorphous nature, magnetoelastic and shape anisotropy contributions govern their magnetic properties. As a result of abovementioned anisotropies, the domain structure of microwires with positive magnetostriction consists of single axial domain and their magnetization process is characteristic of the bistable behavior. 1,2The nanocrystalline microwires have been subject of different studies starting from Finemet based microwires, 3-7 as well as the Nanoperm based ones.8 Such nanocrystalline microwires are usually prepared by heat treatment. However, the microwires undergo strong stresses during the annealing due to the different thermal expansion coefficients of the metallic nucleus and the glass coating. As a result, a ␥-Fe phase appears in annealed glass-coated Finemet microwires instead of desired ␣-͑Fe, Si͒ phase.6,7 When the annealing is performed under high pressure, the formation of ␥-Fe phase is energetically more favorable due to its higher pack density, However, the ␥-Fe phase is nonmagnetic and deteriorates the good soft magnetic properties of nanocrystalline microwires. 6,7 It has been recently shown that partial crystallization of Fe 40 Ni 38 Mo 4 B 16 ribbon leads to the formation of nanocrystalline materials with ␥-͑Fe, Ni͒ nanocrystals having diameter of 10 nm.9 Annealing of such samples at T a = 700 K has been shown to be the optimum annealing temperature to obtain nanocrystalline Fe 40 Ni 38 Mo 4 B 16 alloy with optimized soft magnetic properties ͑lowest magnetostriction, lowest coercive field, and highest initial susceptibility͒. 10,11Since ␥-͑Fe, Ni͒ phase is ferromagnetic contrary to the paramagnetic ␥-Fe phase, it is a promising candidate for preparation of soft magne...

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Nanocrystalline glass-coated FeNiMoB microwires

Komova

Varga

et al. 2008

Applied Physics Letters

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“…Annealing at 675 K leads to the optimum nanocrystalline state of metallic nucleus [3] with lower magnetostriction [8]. This results in the decrease of the switching eld amplitude to the value of the as-cast microwire.…”

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confidence: 99%

“…Annealing at 700 K leads to the steep decrease of magnetostriction [8] that results in a decrease of the switching eld. In contrary to the previous states, the switching eld increases with temperature ( Fig.…”

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confidence: 99%

Temperature Dependence of the Switching Field in Nanocrystalline FeNiMoB Microwires

2014

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We have studied temperature dependencies of the switching eld in as-cast and nanocrystalline glass-coated Fe40Ni38Mo4B18 microwires. The switching eld shows complex temperature dependence in the as-cast state reecting the complex stress distribution induced during annealing. The temperature dependence of the switching eld depends strongly on the stage of nanocrystallization being negative for low temperatures of annealing and positive for annealing at 700 K.

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