Local structure variations in Al₈₉La₆Ni₅ metallic glass

Reduced density functions (RDFs) from electron diffraction measurement of an Al₈₉La₆Ni₅ metallic glass were obtained and analysed using Reverse Monte Carlo (RMC) refinement accompanied by density functional theory calculations. Three different RDFs were observed from regions in close proximity (within microns) of each other, with the first/second peaks respectively located at 2.76/3.32, 2.90/3.46 and 2.96/3.55 Å (all ±0.02 Å). The first type of RDF was found to be the more prevalent. X-ray dispersive spectroscopy and electron energy loss spectroscopy showed no measurable composition variations on this scale. According to the RMC refinements, the variations in the peaks are due to slight lengthening in the mean Al-Al and larger lengthening of the Al-La first-neighbour contacts, while the mean Al-Ni contact shortens. These local structure variations in a nominally homogeneous Al₈₉La₆Ni₅ metallic glass are likely to be important to the understanding of metallic glass properties.