Crystallization behaviour and thermal stability of two aluminium-based metallic glass powder materials

► The crystallization paths and products of Al 86Ni 7Y 4.5Co 1La 1.5 powder have been identified. ► The thermal stability of Al 86Ni 7Y 4.5Co 1La 1.5 powder has been assessed. ► The Al 86Ni 7Y 4.5Co 1La 1.5 powder shows a wide processing window of 75 K. ► The powder has the potential to be consolidated into thick BMG components based on the findings. ► The Al 85Ni 5Y 6Co 2Fe 2 powder shows similar characteristics but inferior thermal stability. The crystallization behaviour and thermal stability of two Al-based metallic glass powder materials, Al 85Ni 5Y 6Co 2Fe 2 and Al 86Ni 6Y 4.5Co 2La 1.5, have been investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron microscopy. Both alloy powders show a distinct three-stage crystallization process with a similar gap of ∼75 K between the onset crystallization temperature ( T x) and the second crystallization temperature. Crystallization occurs by the precipitation and growth of fcc-Al, without intermetallic formation. The apparent activation energy for each stage of crystallization was determined from DSC analyses and the phases resulting from each crystallization stage were identified by XRD and electron microscopy. The critical cooling rate for each alloy powder was calculated from the DSC data. These results are necessary to inform the consolidation of amorphous powder particles of Al 85Ni 5Y 6Co 2Fe 2 or Al 86Ni 6Y 4.5Co 2La 1.5 into thick (>1 mm) metallic glass components.