STUDY OF MECHANICAL ALLOYING OF SM AND FE

Mechanical alloying of Sm and Fe with the composition of SmFe3 was stu died using x-ray-diffraction (XRD), Mossbauer, and magnetization measu rements. Data taken as a function of milling time for up to 20 h show significant changes occurring during ball milling. The XRD studies sho w that the initial crystalline Bragg reflections changed to a broad ma ximum, which is attributed to the formation of an amorphous phase. The initial six-line pattern in the Mossbauer spectrum, characteristic of magnetic ordering, changed to a broad singlet, characteristic of a no nmagnetic material. Magnetization measurements revealed that the coerc ive field was at its maximum after 5 h of milling and decreased sharpl y as the milling time increased. The remanent magnetization was at its maximum between 5 and 10 h of milling. The final product of the ball milling, which exhibited the characteristics of an amorphous paramagne tic material in its XRD and Mossbauer spectrum, was studied after heat treatment. The XRD and the Mossbauer spectra of the heat treated allo y show that substantial changes occurred during heat treatment in that sharp Bragg reflections, characteristic of crystalline materials, rea ppear and the alloy changed from a paramagnetic to a ferromagnetic sta te. (C) 1997 American Institute of Physics.