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

Abstract

Gd 65Fe 20Al 15, Gd 65Fe 15Al 20 and Gd 70Fe 15Al 15 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 Gd 65Fe 20Al 15 bulk amorphous alloy are 808 and 943 K, respectively. Accordingly, the temperature interval of T m and T x, Δ 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 Δ 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 Gd 65Fe 20Al 15, Gd 65Fe 15Al 20 and Gd 70Fe 15Al 15 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 Gd 65Fe 20Al 15 bulk amorphous alloys are investigated.