Effects of y and Tb on the glass forming ability of bulk Mg65Cu25Y10-xTbx amorphous alloys

The bulk Mg65Cu25Y10-xTbx (x=0, 2, 4, 6, 8, 10) amorphous alloy rods of 2 nun in diameter were prepared by a copper mold. casting method. The structure and glass forming ability of the alloys were analyzed by X-ray diffraction (XRD) and differential thermal analysis (DTA), respectively. It is shown that all of the Mg65Cu25Y10-xTbx (x=0, 2, 4, 6, 8, 10) alloys can be prepared into bulk amorphous alloys, the glass forming ability of the alloys becomes stronger with the increment of Tb content. It is the strongest when x=8 then drops at x=10, which can be explained reasonably by calculating the electro-negativity difference Delta x and the atomic size parameter for the alloys. The single smooth melting peak in the DTA pattern indicates that the alloys with a stronger glass forming ability may be eutectic composition when x=6 and 8. The atomic structure parameter A of the two amorphous alloys is far from 0.18, which is deduced from the atom cluster model.