Enhancement of the glass-forming ability by Zr microalloying and its influence on the magnetocaloric properties of bulk amorphous Gd-Co-Al

Microalloying with 1 at. % zirconium dramatically increases the critical size from 3 to 8 mm for Gd-based bulk metallic glasses (BMGs). The enhancement of glass-forming ability originates from the increase in the packing efficiency and high compound forming tendency between Zr and major constituent elements. The maximum magnetic entropy change (-Delta S(Mmax)) and relative cooling power (RCP) of Gd(52.5)Co(18.5)Al(29-x)Zr(x) (x=1) BMG are 9.6 J/kg K and 8.9 x 10(2) J/kg, respectively. Heat capacity data demonstrate that the broad magnetic transition arising from topological disorder is responsible for the high RCP of Gd-based amorphous magnetocaloric materials. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3481923]