Structural and magnetic properties of nanocrystalline Fe–Co–Si alloy powders produced by mechanical alloying

Shyni, P.; Perumal, A.

doi:10.1016/j.jallcom.2015.06.237

Cited by 18 publications

(3 citation statements)

References 32 publications

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“…Zhang et al [46] also reported size dependent enhanced K eff of the Ni nanoparticles in the range between 1.2 × 10 4 J m −3 and 6 × 10 4 J m . High values of K eff have also been reported in other nanocrystalline system [50] prepared by mechanical alloying process. However, in practice, it is impossible to separate these effects individually.…”

Section: Resultsmentioning

confidence: 62%

Mechanical activation on aluminothermic reduction and magnetic properties of NiO powders

Padhan

Sathish

Saravanan

et al. 2017

J. Phys. D: Appl. Phys.

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We report the mechanically activated aluminothermic reduction of NiO [NiO-Al(x wt.%) with x = 0, 20, 40] into NiO-Ni-Al 2 O 3 nanocomposites using high-energy planetary ball milling under dry milling and the resulting structural and magnetic properties. Structural studies reveal that both NiO and NiO-Al powders exhibit a face centered cubic structure with large crystal size reduction. However, the NiO-Al milled powders unveil the process of aluminothermic reaction kinetics, which changes from gradual reaction as a function of milling time for x = 20 powders to self-propagating combustion reaction for x = 40. This allows us to achieve a maximum NiO reduction of 40% and 90% for x = 20 and 40, respectively. The process of NiO reduction by Al is further confirmed through thermal studies. Pure NiO shows an antiferromagnetic (AFM) nature, which transforms into a ferromagnetic (FM) one with the moderate magnetization of about 1 emu g −1 with decreasing crystal size. The formation of FM Ni from AFM NiO matrix in milled NiO-Al powders could be precisely monitored by the change in the magnetization, which increases up to 4 emu g −1 and 28 emu g −1 for the gradual and combustion reactions, respectively. This results in a considerable exchange bias and its magnitude strongly depends on the relative fractions of NiO and Ni phases. Thermomagnetization data confirm the presence of mixed magnetic phases and the component of induced FM phase fades out due to the formation of Ni from the reduction of NiO. The changes in the structural and magnetic properties of milled NiO-Al powders are discussed on the basis of milling time-dependent mechanically activated reduction reaction of NiO into NiO-Ni-Al 2 O 3 nanocomposites. The process of mechanical activation on the aluminothermic reduction allows for a controlled reduction of NiO; thus, it is suitable for the applications in catalysis and the ore reduction process.

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Section: Resultsmentioning

confidence: 62%

Mechanical activation on aluminothermic reduction and magnetic properties of NiO powders

Padhan

Sathish

Saravanan

et al. 2017

J. Phys. D: Appl. Phys.

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“…The values are higher (~12 emu g −1 ) than those of alloy without Co addition [ 24 ]. This increase is also usually associated with better ordering at the atomic level (favoring magnetic interaction between Fe and Co atoms) [ 28 ]. In addition, an increase in coercivity can be produced [ 29 ], as detected in our work.…”

Section: Resultsmentioning

confidence: 99%

Structural, Thermal and Magnetic Analysis of Fe75Co10Nb6B9 and Fe65Co20Nb6B9 Nanostructured Alloys

et al. 2021

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Two nanocrystalline ferromagnetic alloys of the Fe-Co-Nb-B system have been produced by mechanical alloying (MA). Their microstructure, thermal behavior and magnetic response were checked by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometry (VSM). After 80 h of MA, the alloys were nanostructured (bcc-Fe(Co)-rich phase). As the Co content increases, the density of the dislocations decreases. Besides, a higher concentration of Co causes an increase in the activation energy of the crystallization process. The calculated energies, 267 and 332 kJ/mol, are associated to the crystalline growth of the bcc-Fe-rich phase. The Co content of the samples has no effect on the value of the saturation magnetization, whereas the coercivity is lower in the alloy containing less Co. Samples were compacted and heat-treated. Optimal annealing reduces the coercivity by a factor of two. Results were compared with the data of Fe-Nb-B and Fe-Ni-Nb-B alloys.

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“…Many investigations have demonstrated that MM can effectively reduce the particle size of the powder mixtures due to the repeated welding and fracturing of the powder particles in a ball mill [17,[20][21][22] . In some cases, MM can be used to synthesise non-equilibrium alloys [23][24][25] . The much refined microstructure and non-equilibrium phases are beneficial to promote the powder densification of Fe-Mn-Si powder compacts and prevent the formation of the unwanted phases in the sintered microstructure, which deteriorates mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mechanical Milling and Sintering Temperature on the Densification, Microstructure and Tensile Properties of the Fe–Mn–Si Powder Compacts

Hodgson

Cao

2016

Journal of Materials Science & Technology

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Structural and magnetic properties of nanocrystalline Fe–Co–Si alloy powders produced by mechanical alloying

Cited by 18 publications

References 32 publications

Mechanical activation on aluminothermic reduction and magnetic properties of NiO powders

Mechanical activation on aluminothermic reduction and magnetic properties of NiO powders

Structural, Thermal and Magnetic Analysis of Fe75Co10Nb6B9 and Fe65Co20Nb6B9 Nanostructured Alloys

Effects of Mechanical Milling and Sintering Temperature on the Densification, Microstructure and Tensile Properties of the Fe–Mn–Si Powder Compacts

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