Thermal stability and magnetic properties of Gd-Fe-Al bulk amorphous alloys

Gd65Fe20Al15, Gd65Fe15Al20 and Gd70Fe15Al15 bulk amorphous alloys were produced by copper mold casting method with the maximum diameters of 2, 1 and 1 mm, respectively. The crystallization temperature (T-x) and melting temperature (T-m) of the Gd65Fe20Al15 bulk amorphous alloy are 808 and 943 K, respectively. Accordingly, the temperature interval of T-m and T-x, Delta T-m (=T-m - T-x), is as small as 135 K and the reduced crystallization temperature (T-x/T-m) is as high as 0.86. The small Delta T-m and high T-x/T-m values are presumed to be the origin for the achievement of the high amorphous-forming ability of the Gd-Fe-Al bulk amorphous alloy. The Gd65Fe20Al15, Gd65Fe15Al20 and Gd65Fe15Al15 bulk amorphous cylinders with a diameter of I mm exhibit superparamagnetism at room temperature, while the amorphous ribbon shows the paramagnetism at room temperature. Finally, the mechanical properties of Gd65Fe20Al15 bulk amorphous alloys are investigated. (c) 2006 Elsevier B.V All rights reserved.