More attention has been paid to bulk metallic glasses (BMGs) in recent years due to their superior properties, and they have already been developed successfully in many systems such as Zr-, Fe-, Mg-, Cu-, Ti-, Ni-and La-based alloys. [1][2][3][4][5][6] In the meantime, Al-based metallic glass has also received particular interest because of its low density and potential aerospace applications. [7] However, an Al-based metallic glassy rod with a diameter of 1 mm has not yet been produced. Mechanical properties of these materials are usually measured by examining wires and ribbons. [8,9] Therefore, the research and application of Al-based metallic glasses are limited to a large extent due to the sample size. It is important and significant to develop Al-based BMGs. Different methods, such as alloying for example, which are popular and effective in other alloy systems, [10] have been employed to improve the glass-forming ability (GFA) of Al-based metallic glasses. They have little effect on the GFA of Al-based alloy systems. [11,12] The low GFA of Al-based alloys results from the existence of local-ordering clusters and high-melting-temperature phases in the alloy melt, which usually act as nucleation sites. This further promotes crystallization: the precipitation of fcc-Al, and intermetallics, which deteriorate the GFA. In this paper, the successful preparation of an Al-based BMG with a diameter of 1 mm in the Al 85.5 Ni 9.5 La 5 (in atomic percentage) alloy by a melt-treatment technique is described. The treatment is adapted to not only remove the pre-existing nuclei but also to realize a high cooling rate. The thermal and mechanical properties of the Al 85.5 Ni 9.5 La 5 BMG, along with its compressive-fracture behavior are explored for the first time. This work will greatly promote the development and application of Al-based BMGs. Figure 1a shows a photograph of an Al 85.5 Ni 9.5 La 5 BMG cylindrical rod with a diameter of 1 mm. The surface is smooth and lustrous, like other as-cast BMGs. Figure 1b shows X-ray diffraction (XRD) patterns of as-cast ribbons, sheets and rods. It can be seen that only one broad diffraction peak in the 2u range from 358 to 458, characteristic of an amorphous structure, is detected, without any crystalline peaks. Figure 2 shows differential scanning calorimetry (DSC) curves of the as-cast ribbons, sheets and rods. The three traces display similar glass-transition and crystallization behaviors and indicate similar amounts of exothermic heat, which is consistent with the XRD results. In comparison to the GFA of Al 86 Ni 9 La 5 reported in ref.[13], we found that a larger size of amorphous alloy is obtained with our casting strategy than with the ordinary wedge-casting method. Fig. 1. a) A photograph of the 1 mm diameter cylindrical rod. b) XRD patterns of the master alloy and as-cast samples.
