A. Inoue et al., HARD MAGNETIC-PROPERTIES OF BULK AMORPHOUS-ALLOYS, Science Reports of the Research Institutes, Tohoku University, Series A: Physics, Chemistry, and Metallurgy, 44(2), 1997, pp. 261-269
Citations number
35
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
The amorphous phase in the Nd-Fe-Al and Pr-Fe-Al systems is formed in
extremely wide composition ranges of 0 to 90 at% Fe and 0 to 93 at% Al
by melt spinning. Ferromagnetic Ln(90-x)Fe(x)Al(10) (Ln=Nd or Pr) bul
k amorphous alloys with high coercive force at room temperature are ob
tained by a copper mold casting method. The maximum diameter of the cy
lindrical amorphous samples is 12 mm for the Nd-30%Fe-Al alloy and 3 m
m for the Pr-30%Fe-Al alloys and decreases with deviating Fe content.
Neither glass transition nor supercooled liquid region is observed in
the temperature range before crystallization (T < T-x), which is diffe
rent from other bulk amorphous alloys exhibiting wide supercooled liqu
id regions. The extremely high T-x/T-n and small Delta T-m(=T-m-T-x) v
alues are the reason for the achievement of large glass-forming abilit
y in these systems. The bulk amorphous Ln(60)Fe(30)Al(10) alloys are f
erromagnetic with the Curie temperature (T-c) of 515 to 600 K which ar
e much higher than those for Nd-Fe and Pr-Fe binary amorphous ribbons.
The remanence (B-r) and intrinsic coercive force (H-i(c)) are 0.089 t
o 0.122 T and 277 to 321 kA/m, respectively, and the crystallization t
o Ln+Al(2)Ln+delta phases causes a ferromagnetic- to -paramagnetic pha
se transition. Thus, the hard magnetic properties are achieved only in
the amorphous state.