Effect of substitution of vanadium in Nd2Fe14B studied by Mössbauer spectroscopy

Kamal, Raj; Lovleen,

doi:10.1016/0022-5088(89)90150-1

Cited by 7 publications

(5 citation statements)

References 19 publications

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“…This is consistent with the presence of Al, which leads to a significant decrease of the hyperfine field at each Fe site of the Nd 2 Fe 14 B phase [25]. Co also leads to the decrease of the mean hyperfine field of the Nd 2 Fe 14 B phase [21] whereas V increases it [23]. The difference in the mean hyperfine field between samples DCVA and CVA is attributed to the presence of Dy which leads to a slight increase in the hyperfine fields at the different sites [24].…”

Section: Resultssupporting

confidence: 82%

“…Previous microstructural studies performed on a sample similar to sample DCVA showed that the V content is less than 1% [3]. On the other hand, both Mo and V appear to occupy preferentially the same Fe sites as Co [22,23]. Consequently, their influence on the Mössbauer spectra was considered together with that of Co.…”

Section: Mössbauer Analysismentioning

confidence: 99%

“…Previous studies showed that the presence of additional elements substituted at Fe sites in the Nd 2 Fe 14 B unit cell modifies the Curie temperature of the Nd 2 Fe 14 B phase. In particular, some additional elements such as Co [27], V [23], Dy [31], Mo [22] and Nb (for small concentrations) [30] are known to increase the value of T C , Co having the greatest effect on the Curie temperature. On the contrary, Al leads to a slight decrease of T C [32].…”

Section: (See Table 6) a Reduction Ofmentioning

confidence: 99%

“…Figure 6 displays the displacement temperature curves of the four samples, from which the Curie temperatures of the hard matrix were determined to be 360 • C (633 K) for DCVA, 358 • C (631 K) for CVA, 362 • C (635 K) for CMA and 320 • C (593 K) for DNA with an accuracy on T C of 2 • C.Previous studies showed that the presence of additional elements substituted at Fe sites in the Nd 2 Fe 14 B unit cell modifies the Curie temperature of the Nd 2 Fe 14 B phase. In particular, some additional elements such as Co[27], V[23], Dy[31], Mo[22] and Nb (for small concentrations)[30] are known to increase the value of T C , Co having the greatest effect on the Curie temperature. On the contrary, Al leads to a slight decrease of T C[32].…”

mentioning

confidence: 99%

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Microstructure and corrosion resistance of Nd-Fe-B magnets containing additives

Steyaert¹,

Breton²,

Teillet³

1998

J. Phys. D: Appl. Phys.

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The oxidation behaviour of the phase in Nd-Fe-B sintered magnets containing additional elements (Al, Co, V, Nb, Mo) was investigated by Mössbauer spectrometry. The microstructure of the different samples was first characterized. Added elements were detected in both intergranular and intragranular precipitates. The presence of X-Fe-B (, V, Mo) precipitates was evidenced by high-resolution scanning electron microscopy, x-ray diffraction and Mössbauer spectrometry. The presence of Al and Co substituted to Fe in the phase was evidenced, and quantified using Mössbauer spectrometry and Curie temperature measurements. Powdered magnets sieved to a particle size less than m were oxidized in an ambient air furnace in the 200-C temperature range. These conditions are known to allow the oxidation process of the hard matrix (namely the intragranular diffusion process) to be followed accurately. The experimental oxidation kinetics were determined using Mössbauer spectrometry and fitted according to a single-particle analysis model. The results show a decrease of the dissociation rate of the hard matrix compared with the rate obtained for a sintered magnet containing no additives. As the activation energy was found to be comparable for each sample (106-112 kJ ), the pre-exponential factor of the diffusivity has a greater influence on the dissociation rate ( for the magnets containing V or Mo and for the magnet containing Nb, compared with for a magnet without additives). The slowing down of the dissociation rate is attributed to the presence of corrosion-resistant X-Fe-B (, V, Mo) intragranular precipitates in the oxidized layer and appears to be strongly dependent on the density of the intragranular precipitates.

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Section: Resultssupporting

confidence: 82%

Section: Mössbauer Analysismentioning

confidence: 99%

Section: (See Table 6) a Reduction Ofmentioning

confidence: 99%

mentioning

confidence: 99%

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Microstructure and corrosion resistance of Nd-Fe-B magnets containing additives

Steyaert¹,

Breton²,

Teillet³

1998

J. Phys. D: Appl. Phys.

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“…The most studied series is that of R 2 Fe 14−x Co x B pseudoternary compounds. The mean values of the 57 Fe hyperfine field decrease with respect to the value for x = 0 (Lovleen and Kamal 1989). This decrease is characteristic for all sites (Sano et al 1989).…”

Section: D Magnetismmentioning

confidence: 79%

Permanent magnets based on R-Fe-B and R-Fe-C alloys

Burzo

1998

Rep. Prog. Phys.

208

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A review is given on the basic properties of 2:14:1 hard magnetic phases as well as technological procedures used for manufacturing R-Fe-B and R-Fe-C permanent magnets. First, we analyse the phase diagrams, crystal structure of hard magnetic phases and composition ranges in which these phases form solid solutions, as a result of various types of substitution. Then, the magnetic properties of R 2 Fe 14 B-, R 2 Fe 14 C-and R 2 Co 14 Bbased compounds are described. The routes used for manufacturing R-Fe-B and R-Fe-C permanent magnets are detailed. The magnets' microstructure as well as their coercivities are described in correlation with composition and manufacturing routes. The properties of nanostructure magnets are then presented. Finally, the stability of Nd-Fe-B and Nd-Fe-C magnets in various working conditions is analysed.

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