Architecture and magnetism of alnico

Zhou, Lin; Miller, M.K.; Lü, Ping; Ke, Liqin; Skomski, Ralph; Dillon, H.; Xing, Q.; Palasyuk, Andriy; McCartney, Martha R.; Smith, David J.; Constantinides, S.; McCallum, R. W.; Anderson, Iver E.; Antropov, Vladimir; Kramer, M. J.

doi:10.1016/j.actamat.2014.04.044

Cited by 148 publications

(114 citation statements)

References 22 publications

Supporting

Mentioning

109

Contrasting

Order By: Relevance

“…3 shows the range of rod diameters and coercivities typically encountered in laboratory-scale and industrial practice [6,7]. Compared to the Stoner-Wohlfarth predictions (dashed line), the single-rod approximation of Figs.…”

mentioning

confidence: 99%

“…Fourth, it is known experimentally that the rods or "wires" of the magnetic phase undergo crossing and branching [6,7,14]. These features are likely to strongly affect coercivity, and their treatment requires demanding numerical calculations.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

“…The detailed microstructures strongly depend on alloy composition and heat treatment conditions. Details of alnico alloy fabrication and microstructure characterization are reported elsewhere [7,19].…”

mentioning

confidence: 99%

“…Alnico magnets-a family of nanostructured alloys consisting primarily of Fe, Al, Ni, and Co-are an exception, because their magnetic anisotropy and hysteresis originate almost entirely from magnetostatic dipole-dipole interactions [4][5][6][7]. These materials have attracted renewed attention in the context of magnetic materials that are free of rare-earth elements and do not contain other expensive elements, such as Pt [7][8][9][10][11][12][13][14]. The magnetic anisotropy of alnicos reflects their peculiar nanostructure, where highmagnetization rods with an approximate composition of FeCo (α 1 -phase) are embedded in an essentially nonmagnetic Al-Ni-rich matrix (α 2 -phase) [4][5][6][7][14][15][16][17][18].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Simulation of alnico coercivity

Skomski

Hoffmann

et al. 2017

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Micromagnetic simulations of alnico show substantial deviations from Stoner-Wohlfarth behavior due to the unique size and spatial distribution of the rod-like Fe-Co phase formed during spinodal decomposition in an external magnetic field. The maximum coercivity is limited by single-rod effects, especially deviations from ellipsoidal shape, and by interactions between the rods. Both the exchange interaction between connected rods and magnetostatic interaction between rods are considered, and the results of our calculations show good agreement with recent experiments. Unlike systems dominated by magnetocrystalline anisotropy, coercivity in alnico is highly dependent on size, shape, and geometric distribution of the Fe-Co phase, all factors that can be tuned with appropriate chemistry and thermal-magnetic annealing.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Simulation of alnico coercivity

Skomski

Hoffmann

et al. 2017

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

Oxidation and Hot Gas Corrosion of Al–Cr–Fe–Ni‐Based High‐Entropy Alloys with Addition of Co and Mo

et al. 2021

View full text Add to dashboard Cite

Multicomponent, high‐entropy alloys (HEAs) are promising candidates for replacing conventional alloys in high‐temperature applications. Herein, the high‐temperature corrosion of AlCrFeNiX0.5 (X = Co, Mo) is investigated. The samples are tested for their oxidation resistance at temperatures up to 1200 °C for 120 h and their behavior in NaCl/Na2SO4 at 900 °C for 96 h. They are benchmarked against commercial alloys such as FeCrAl. Despite the same contents of Al and Cr, the HEAs form different oxide layers showing very different oxidation resistance. The type of oxide is related to the multiphase microstructure. The samples exhibit different amounts of ordered and unordered body‐centered cubic (bcc) phase. The Co‐containing specimen shows an oxidation resistance that performs similarly well as FeCrAl. Its behavior is ascribed to the formation of an Al2O3 layer, which is very stable at high temperatures. The sample with X = Mo exhibits an additional Mo‐rich sigma phase, thus posing the risk of catastrophic oxidation. However, the Mo‐containing HEA is more resistant in the environment of molten salt. Preoxidation treatment at a lower oxygen partial pressure proves to prolong life span of the Mo‐containing HEA in hot air. Furthermore, a positive impact on oxidation resistance by addition of Y is affirmed.

show abstract

Balancing Scattering Channels: A Panoscopic Approach toward Zero Temperature Coefficient of Resistance Using High‐Entropy Alloys

et al. 2018

View full text Add to dashboard Cite

global positioning system (GPS) devices. [2] Moreover, to further improve sensitivity and for use in controlled heating applications (e.g., in furnaces) by resistance heating, a high electrical resistivity (ρ) is desired. [1,3,4] Designing novel materials with little or no change in ρ over a very wide range of temperatures, however, remains a big challenge, which is indicated by the fact that more than a century after their discovery, Constantan (Cu-Ni) and Manganin (Cu-Mn-Ni) based alloys are still the most widely used materials in these contexts. [1,3,4] A crucial material parameter for the abovementioned applications is the temperature coefficient of resistance (TCR), Δρ/ρ 0 ΔT, which measures the variation of the electrical resistivity within a certain temperature range where ρ 0 , Δρ (= ρ − ρ 0 ) and ΔT (= T − T 0 ) are the resistivity at the lower temperature (typically the resistivity near 0 K, unless stated otherwise), difference in resistivity between the higher and the lower temperatures, and the temperature difference between the high and low temperatures, respectively. [5,6] Metals commonly display positive TCR values, which originate from an increasing probability of electrons to experience thermally induced scattering events. For simple metals, phonons represent the dominating scattering channel already at ambient temperatures exhibiting a linear temperature dependence for T > T D /3, where T D is the Debye temperature. [7,8] At very low temperatures, on the other hand, the resistivity is dominated by scattering from impurities and defects giving rise to the socalled residual resistivity, ρ 0 . In this work we will refer to the resistivity obtained at the lowest measurement temperature ≈2-5 K as the residual resistivity, ρ 0 . For the Manganin reference, we use the ρ 0 and ρ 300K that are obtained by fitting (cf. the Supporting Information). [9] Moreover, in metals with magnetic impurities, scattering from magnons (spin-waves) can reach significant levels at low temperatures. [10] In specific cases, where magnetic atoms are embedded in nonmagnetic host metals, the Kondo effect (temperature dependent scattering of conduction electrons by magnetic impurities at low temperatures) can play a dominant role at temperatures near zero Kelvin. [9] The origin of sign and magnitude of the TCR is still a subject of debate. [5][6][7][8]11] In the 1960s, Ioffe and Regel defined the minimum mean-free path (l min ) of the charge carrier to be ≈a (i.e., the interatomic spacing). [7,8,12] This limit, commonly known as Designing alloys with an accurate temperature-independent electrical response over a wide temperature range, specifically a low temperature coefficient of resistance (TCR), remains a big challenge from a material design point of view. More than a century after their discovery, Constantan (Cu-Ni) and Manganin (Cu-Mn-Ni) alloys remain the top choice for strain gauge applications and high-quality resistors up to 473-573 K. Here, an average TCR is demonstrated that is up to ≈800 times smaller in the tempera...

show abstract

Architecture and magnetism of alnico

Cited by 148 publications

References 22 publications

Simulation of alnico coercivity

Simulation of alnico coercivity

Oxidation and Hot Gas Corrosion of Al–Cr–Fe–Ni‐Based High‐Entropy Alloys with Addition of Co and Mo

Balancing Scattering Channels: A Panoscopic Approach toward Zero Temperature Coefficient of Resistance Using High‐Entropy Alloys

Contact Info

Product

Resources

About