Crystallographic orientation relationships between primary silicon and aluminium crystals

Abstract

Crystallographic orientation relationships between the primary silicon crystal and the aluminium crystal heterogeneously nucleated on the silicon surface in hypereutectic Al-Si alloys, were studied by the micro-focus X-ray diffraction analysis. The apparently random orientation relationships obtained by X-ray analysis have been classified into simple relationships by taking the twinning in the primary silicon crystals into consideration. The epitaxial relationships between silicon and aluminium crystals in untreated alloys, and that in sodium-treated alloys, are found to be distinctly different.