NANOSTRUCTURE DETERMINATION OF A SPLAT-COOLED AND LASER-QUENCHED NB40NI60 ALLOY BY SCANNING TUNNELING MICROSCOPY

The STM has been used to study the morphologies and nanostructures of splat-cooled and laser-quenched Nb40Ni60 alloys. The experiments are performed under ultra high vacuum at room temperature. On Ar+ ion etched splats, islands 10-20 angstrom in diameter with a maximum corrugation of 4 angstrom can be observed. Atomic-scale features of 3-4 angstrom have been observed. In a few cases nanostructures 30-50 angstrom which contain a fine structure of 3 angstrom dimension are found. These nonostructures could be assigned as nanocrystallites. Laser quenching of amorphous splats results in the formation of distinctly different surface morphologies, also on the scale of 20-30 angstrom and around 10 angstrom in height. The STM has been shown to be an effective tool for characterizing surface structures in amorphous metals.