Magnetic and structural characterization of the [Fe1-xCox](1-y)Nb-y systemin the range 0 <= x <= 1, 0 <= y <= 0.33

The main magnetic and structural characteristics of the phases present in t he [Fe1-xCox](1-y)Nb-y ternary system in the range 0 less than or equal to x less than or equal to 1 and 0 less than or equal to y less than or equal to 0.33 were investigated. The phases observed are based on the alpha -Fe o r epsilon -Fe2Nb structures, for x up to about 0.75, and on the gamma -Co a nd epsilon -Co2Nb structures in the neighborhood of the Co-Nb edge. While a strict dilution of about 0.4 at% Nb in alpha-(Fe + Co) does not affect sig nificantly its magnetization, a significant solubility of about 4 at% Nb in gamma -Co reduces that parameter by about 12%. The evolution of the hyperf ine field of alpha-(Fe + Co) at room temperature has shown that the presenc e of Nb in that phase keeps the structure in the disordered state. A phase transformation was observed in a containing 21-27 at% Nb, as the phase beco mes magnetic above 20 K after filing the, material, with increasing B-HF as x increases up to 0.75. (C) 2001 Elsevier Science B.V. All rights reserved .