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 (Tx) and melting temperature (Tm) of the Gd65Fe20Al15 bulk amorphous alloy are 808 and 943 K, respectively. Accordingly, the temperature interval of Tm and Tx, ΔTm (=Tm − Tx), is as small as 135 K and the reduced crystallization temperature (Tx/Tm) is as high as 0.86. The small ΔTm and high Tx/Tm 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 Gd70Fe15Al15 bulk amorphous cylinders with a diameter of 1 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.