| Metallic glasses offer enhanced properties in processing and wear over their crystalline counterparts. Aluminum-based metallic glasses are further desired for their high strength-to-weight ratio and low cost. It has been observed that additions of very small amounts of additional elements to the base aluminum-based alloys can dramatically improve glass formability. Here, the effects of microalloying on glass formation and stability are systematically investigated by substituting 0.5 atomic percent of all 3-d transition metals for Al in Al88Y7Fe5 alloys. X-ray diffraction, differential scanning calorimetry, differential thermal analysis, and transmission electron microscopy studies demonstrate enhanced glassy characteristics and stability in the microalloys. Further collaborative investigations using high-energy synchrotron X-ray diffraction, extended X-ray absorption fine structure analysis, and atom probe tomography reveal enhanced short- and medium-range order as well as a suppression of phase separation upon microalloying. A novel investigation method, fluctuation electron microscopy, was employed to quantify the extent of medium range order in the alloys by statistical analysis of microdiffraction patterns. Significant enhancements were made to the methodological protocol for this new technique, allowing for greatly enhanced experimental reproducibility. |
