Microstructure of rapidly solidified Al–20Si alloy powders

Microstructural details of rapidly solidified Al–20Si alloy powders by gas atomization were examined by transmission electron microscope. The as-atomized alloy powder consists of primary and eutectic Si embedded in Al matrix. Typical sizes of Al grain, primary Si and eutectic Si measured in the powder of 40 μm in diameter are 1 μm, 3 μm and 100 nm, respectively. Twin and stacking faults were found to present in the precipitated Si. The alloy powder has semicoherently bonded interface between Al {1 1 1} and Si {1 1 1} with a specific lattice spacing.