The melting point of metals decreases on the formation of nano-crystals. Premelting of surfaces and grain boundaries has also been reported. The current study pertains to annealing of solutionized Cu-2wt.%Fe alloy thin film samples in the temperature regime of 200-300°C. Transmission electron microscopy specimens have been used as free-standing thin films and the annealing of the samples are performed by two methods: (i) in-situ in a TEM, (ii) ex-situ after sealing the samples in vacuum. In the in-situ annealing treatment the power to the heater was switched off after annealing, while the ex-situ samples were quenched in water. Formation of nanocrystals with grain size of about 6 to 10 nm is observed in both kinds of samples after annealing and is occurs after 10 minutes of annealing at 250°C in the in-situ sample. Given that the solidus temperature of the alloy is 1064°C, these observations represent fast changes in a short period of time. We postulate that the samples have undergone surface premelting followed by solidification. Due to rapid quenching of the molten layer on the substrate of the same materials, nano-crystals on the surface are observed

Figures:

In-Situ TEM image of Nanograins of Cu2wt%Fe free standing thin Film at 200C

« Back to The 16th European Microscopy Congress 2016

EMC Abstracts - https://emc-proceedings.com/abstract/nanograin-formation-due-to-premelting-in-free-standing-thin-films/