Mechanical properties of Al—Si and Al—Fe powder metallurgy alloys

The relationship between mechanical properties and microstructure, and the mechanism of strengthening of Al—18 wt%Si and Al—8 wt%Fe alloys made by powder metallurgy process were investigate. Si particles are observed in the Al—18 wt% Si alloys, and Al₃Fe and Al₆Fe particles are observed as intermetallic compounds in the Al—8 wt%Fe alloys using an transmission electron microscopy. Work hardening mechanism of the alloys is summarized as follows: Firstly dislocation loops are formed around fine dispersion particles. Then, many dislocation such as like prismatic loops pile up as deformation progresses. Finally, stress concentration induced by dislocation loops is subjected to the plastic release. The strength of those alloys are related closely to both the volume fraction of particles and the particle size.