Title :
Characterisation of rare earth-transition metal alloys with resistivity measurements
Author :
Gutfleisch, Oliver ; Verdier, Marc ; Harris, Ivor Rex ; Ray, Alden E.
Author_Institution :
Sch. of Metall. & Mater. Sci., Birmingham Univ., UK
Abstract :
Precipitation hardening in Sm 2(Co,Fe,Cu,Zr) 17-type alloys and commercial magnets and magnetic and phase transitions and hydrogen absorption and desorption of Nd-Fe-B-type alloys are investigated by electrical resistivity measurements. Changes in the resistivity of a Sm(Co .63Fe .27Cu .08Zr .02) 8.35 alloy after solid solution treatment of 1155 degrees C and during isothermal aging at 800 degrees C can be attributed to the precipitation of the platelet and the grain boundary phase. In commercial sintered magnets, an anisotropy in the electrical resistivity is found for the fully heat treated condition when measuring parallel to either the basal plane or the c-axis. A Nd 14.68Dy 0.94Al 0.62-Nb 0.5B 6.79 alloy is studied employing in-situ measurements of the electrical resistivity and the Curie-point. The formation of the liquid grain boundary phase and the HDDR (hydrogenation, disproportionation, desorption, recombination)-process are observed.<>
Keywords :
Curie temperature; ageing; desorption; electrical conductivity of crystalline metals and alloys; ferromagnetic properties of substances; grain boundaries; heat treatment; permanent magnets; precipitation hardening; rare earth alloys; sorption; transition metal alloys; 1155 degC; 800 degC; Curie-point; H; HDDR; Nd-Fe-B-type alloys; Nd/sub 14.68/Dy/sub 0.94/Al/sub 0.62/-Nb/sub 0.5/B/sub 6.79/ alloy; NdFeB; Sm/sub 2/(Co,Fe,Cu,Zr)/sub 17/-type alloys; Sm/sub 2/(CoFeCuZr)/sub 17/; anisotropy; desorption; disproportionation; grain boundary phase; hydrogen absorption; hydrogenation; isothermal aging; liquid grain boundary phase; magnetic transitions; magnets; phase transitions; platelet; precipitation hardening; rare earth-transition metal alloys; recombination; resistivity measurements; sintered magnets; solid solution treatment; Absorption; Conductivity measurement; Electric resistance; Electric variables measurement; Grain boundaries; Hydrogen; Magnetic anisotropy; Magnets; Perpendicular magnetic anisotropy; Samarium alloys;
Journal_Title :
Magnetics, IEEE Transactions on