Abstract
The effects of a small amount of CaO addition (0.3 mass%) on the microstructure and damping properties of AM50 casting alloys have been investigated. The added CaO contributes to the formation of an Al2Ca phase but reduces the total amount of compound particles by decreasing the β phase content. The AM50–CaO alloy shows a slightly higher damping level within the strain-amplitude dependent region than does the alloy without CaO. The lower number density of compound particles acting as strong pinning points for dislocations is thought to be responsible for the improvement in the damping capacity.
