INTERACTION OF ALPHA-PARTICLE BEAMS WITH METALLIC GLASSES

Samples of Fe40Ni38Mo4B18, Fe78B13Si9 and Fe66Co18B15Si1 metallic glas ses, selected with respect to the different values of their magnetostr iction constants, were irradiated with alpha particle beams (W = 2.8 M eV) using radiation doses of 10(16) and 10(17)/cm(2). The fundamental effects underlying the interaction of alpha particle beams with amorph ous magnets were studied by transmission and conversion electron Mossb auer spectroscopy (CEMS), hysteresis loops and a.c. susceptibility mea surements, and scanning electron microscopy (SEM). The evolution of ph ases and microstructure during the radiation-induced amorphous-to-crys talline transformation was found to depend on the particle flux and sa mple composition. Differences between bulk and surface behaviors of th e magnetic texture and constituent phases were evidenced. Radiation-dr iven changes in the saturation magnetic moment, coercive held, real an d imaginary components of the a.c. response were observed for all samp les studied and found to depend on the radiation dose employed. The su rface morphology of the radiation-induced crystalline precipitates was shown to vary as a function of composition, such that both spherical and dendritical modes of growth were observed. By stimulating unconven tional pathways for the crystallization process, the interaction of al pha particle beams with glassy ferromagnets offers unique opportunitie s to understand the fundamentals of nucleation and growth in these sys tems. (C) 1998 Acta Metallurgica inc. Published by Elsevier Science Lt d. All rights reserved.