Magnetic Properties of Rapidly Quenched Nd₁₀Fe_85-xT_xB₅ (T=Zr, Nb) Alloys

Abstract

We propose some improvements in the form of the eikonal wavefunction and a more rigorous evaluation of the integral for the DWBA amplitude for electron-nucleus scattering as given by Yennie. Our calculations are found to be in closer agreement with the phase-shift results than those of Yennie er al (for e'-Au scattering) and Rosenfelder (for e--Pb scattering based on the eikonal approximation of the T matrix). The improved eikonal method is applied to the study of the isotopic effect in e--Ti scattering. The effect of the addition of a small oscillatory part to the smoothly varying nuclear charge distribution for e--32S scattering at high momentum transfer is also investigated with the help of our eikonal method.

Permanent magnetic properties of melt-spun (M=Cu, Nb, Zr, Ti, V, Mo) ribbons

“…According to the values of unit cell volume and Curie temperature, the remaining carbon content is estimated to be about y = 0.5 for Sm 2 Fe 14 NbGa 2 C y ribbons. Although the carbon content is reduced and this results in a reduction of coercivity, the fine NbFe 2 grains may increase the coercivity [12], so the coercivity of Sm 2 Fe 14 NbGa 2 C is almost the same as that of Nb-free ribbons. However, the coercivities decrease for Sm 2 Fe 15−x Nb x Ga 2 C ribbons with x > 1, which may be caused by more NbC phase formation.…”

“…It is therefore necessary to explore some element additions which reduce the crystalline size and enhance the coercivity in order to help further studies on exchange coupling materials in the future. From melt-spun Nd-Fe-B and Pr-Fe-B it is known that Cu, Nb and Zr additions can reduce the grain size and increase the coercivity [11,12].…”

Exchange coupled nanocomposite hard magnetic alloys

“…This coarse microstructure results in poor magnetic properties for the composite structure. However, additions of small concentrations of refractory elements (such as Zr or Nb) have been reported as being useful in controlling the grain size of both the a-Fe and 2 : 14 : 1 phases in NdFeB [60][61][62] and in PrFeB 58,63-66 nanocrystalline alloys and, hence, in improving the magnetic properties relative to the ternary overquenched and annealed REFeB alloys. Zr and Nb may be segregating out of the growing soft phase crystallites into the interfaces with the glassy phase matrix and thus retarding the growth of the crystallites, in a manner similar to that reported for Finemet soft magnetic nanocomposite alloys.…”

“…115 The effect of an amorphous residual phase (preserved after partial devitrification of an initially amorphous state) on the magnetic properties of nanocomposite a-Fe/Fe 3 B/RE 2 Fe 14 B alloys has been reported as being beneficial for enhancing the coercivity, a value as high as 227 kA m 21 being observed for RE contents of 4 at-%, in combination with a useful (BH) max of 110 kJ m 23 . 61,116,117…”

Magnetic properties and microstructures of α-Fe/Nd2Fe14B nanocomposite microalloyed with Zr

“…͓DOI: 10.1063/1.1447510͔ Nanocomposite magnets composed of exchange coupled nanograins of soft and hard magnetic phases receive much interest for a potential application to a medium performance permanent magnets. 1,2 Addition of Zr to the ␣-Fe/Nd 2 Fe 14 B system was reported to decrease the coercivity in ball-milled nanocrystalline Nd 2 Fe 14 B magnets 3 and ␣-Fe/Nd 2 (Fe, Co, Zr) 14 B nanocomposite magnets; 4 however, Zr addition was also found to increase coercivity in the meltspun Nd 10 Fe 85 B 5 alloy, 5 Nd 2 (Fe, Co) 14 B alloy, 6 Sm 2 Fe 15 Ga 2 C x /␣-Fe nanocomposite 7 and PrFeB nanophase alloys. 8 However, there is little understanding on the underlying mechanism of Zr addition in influencing the magnetic properties of these nanocomposite magnets.…”