Experimental evidence of structural transition at the crystal-amorphous interphase boundary between Al and Al2O3

High-resolution transmission electron microscopy observations on the structure of the interphase boundary between crystalline Al and amorphous Al2O3 coating reveal that an interfacial melting transition of Al occurs at 833 K, which is distinctly lower than the bulk melting point of Al. The crystalline lattice planes of Al near the interface bend or small segments of crystalline Al deviated from the matrix Al grains are formed. Stand-off dislocations formed at the interphase boundary are also observed. The amorphous Al2O3 coating plays an important role in retaining the evidence for structural transition at high temperature to room temperature, which makes it possible to make experimental observations. (author)