Effect of Be on Aging Behavior of an Al11Si3Cu Cast Alloy

Effect of Be addition on age hardening and precipitation behaviors of Al11Si3Cu alloy was investigated by hardness measurement and differential scanning calorimetry (DSC) analysis. The age hardening results show that 0.25% Be addition increases the peak hardness of Al11Si3Cu alloy about 20HV. DSC results show that Be addition inhibits precipitation of Cu and /Si clusters or GP zones before artificial aging and increases the volume of theta' precipitates during artificial aging. The precipitation dynamic analysis results show that theta' phases are two-dimensional precipitates that is unaffected by Be addition. The nucleation density dependent parameter k for Be containing alloy is 2.75 times of the base alloy, which suggests that Be addition accelerates the nucleation density of theta' phases.