Characterisation of rare earth-transition metal alloys with resistivity measurements

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.<>