Title :
Hard magnetic bulk amorphous alloys
Author :
Inoue, Akihisa ; Zhang, Tao ; Takeuchi, Akira
Author_Institution :
Inst. of Mater. Res., Tohoku Univ., Sendai, Japan
fDate :
9/1/1997 12:00:00 AM
Abstract :
An amorphous phase in Ln-Fe-Al (Ln=Nd and Pr) systems is formed in wide composition ranges of 0 to 90 at% Fe and 0 to 93 at% Al by melt spinning. Ferromagnetic Ln90-xFexAl10 bulk amorphous alloys with high coercive force (iHc) at room temperature are obtained by copper mold casting. The maximum diameter of the cylindrical amorphous samples is 12 mm for the Nd-30%Fe-Al alloy and 3 mm for the Pr-30%Fe-Al alloys and decreases with deviating Fe content. The extremely high Tx/Tm and small ΔTm(=Tm-Tx), which are evaluated by the crystallization temperature (Tx) and melting temperature (Tm), are the reason for the achievement of large glass-forming ability in these systems. The bulk amorphous Ln60 Fe30Al10 alloys are ferromagnetic with the Curie temperature of 515 to 600 K which are higher than those for Nd-Fe and Pr-Fe binary amorphous ribbons. The remanence and iHc are 0.089 to 0.122 T and 277 to 321 kA/m, respectively and the crystallization to Ln+Al2Ln+δ causes a ferromagnetic-to-paramagnetic transition. Thus, the hard magnetic properties are achieved only in the amorphous state
Keywords :
Curie temperature; aluminium alloys; amorphous magnetic materials; coercive force; crystallisation; ferromagnetic materials; ferromagnetic-paramagnetic transitions; iron alloys; melt spinning; metallic glasses; neodymium alloys; permanent magnets; praseodymium alloys; remanence; 515 to 600 K; Curie temperature; Fe content; Nd-Fe-Al; Pr-Fe-Al; copper mold casting; crystallization temperature; ferromagnet; ferromagnetic-to-paramagnetic transition; glass-forming ability; hard magnetic bulk amorphous alloys; high coercive force; melt spinning; melting temperature; remanence; room temperature; Aluminum alloys; Amorphous magnetic materials; Amorphous materials; Casting; Coercive force; Copper alloys; Crystallization; Iron alloys; Spinning; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
