Inhibited cold compactibility of rapidly solidified Al–Si alloy powder with large solidification rate

• Powder compactibility is more inhibited with the increase of solidification rate.
• Microstructural characteristics determine the powder deformation capacity.
• Morphology, size, and distribution of Si phases influence the deformation capacity.
• Fracture of primary Si crystals contributes to the densification behavior.

Rapidly solidified powder with refined microstructure is widely used as raw materials for powder metallurgy route. Understanding and controlling the densification behavior of the powder are important to obtain high quality products. In this work, the effect of solidification rate on cold compactibility is investigated via compaction of the rapidly solidified hypereutectic Al–Si alloy powder with different particle sizes. The deformation capacity of the powder with different particle sizes is investigated by linear compaction equations. Furthermore, the microstructure and fracture surface of the compacts are also examined to understand the powder deformation behavior during compaction. The results indicate that the deformation capacity is significantly affected by the microstructure characteristics and the microhardness of Al matrix controlled by solidification rate (or particle size).

Cold compactibility of rapidly solidified Al–Si alloy powder decreases with the particle size. The main reasons are the Si phases are suppressed in size, morphology, and distribution and the microhardness is increased due to high-level of supersaturation at large solidification rate. Powder plastic deformation capacity decreases with the particle size results in the poor compactibility of the fine powder.Figure optionsDownload as PowerPoint slide