Orientation of nanocrystals in rapidly solidified Al-based alloys and its correlation to the compound-forming tendency of alloys

The orientation of nanocrystals in rapidly solidified Al-based alloys has been investigated using transmission electron microscopy (TEM). It was found that the selected-area electron diffraction (SAED) patterns of nanocrystals in the melt-spun Al-Sr, Al-Ce, Al-Sb and Al-Ce-Sr alloys exhibit Bragg reflections with a monocrystalline characteristic, indicating that the nanocrystals in a local area form in the same growth orientation. In addition, there exist epitaxial orientation relationships between nanocrystals and the α-Al matrix in some areas. The nanoscale Sn and Si particles are randomly oriented in the melt-spun Al-Sn and Al-Si alloys, however, and the SAED patterns show spotty rings. The intensity of the interaction between relevant elements and Al increases in the following sequence: Si, Sn, Sb, Ce and Sr, as well as the compound-forming tendency of alloys. Furthermore, the orientation of nanocrystals in the melt-spun Al-based alloys is correlated to the compound-forming tendency of the alloys.