|
The effect of adding magnesium on the aging behavior of Al-Zn- Mg alloy reinforced with aluminum (Al2O3) was studied using differential scanning calorimeter(DSC) technique, hardness measurement. The magnesium contents were varied from 1.23wt% to 2.97wt%. The addition of magnesium was found to increase the amount of η'-phase formation in composites. The formation enthalpy of composites was 0.932cal/g and 1.375cal/g for lower magne- sium content(1.23wt%) and higher magnesium content(2.97 wt%) respectively. The time needed for the saturation of precipiat- ing in the composites changed from 12 hr to 48hr as the magne- sium content increased from 1.23wt% to 2.97wt%. The maximum hardness occurred in composites with 2.97wt% Mg that contained a maximum amounts of η'-phase precipitates. The hardness of the composites was always less than that of monoli- thic alloys because of alumina fibers caused suppression of η' formation in composites. Difference of wearability between composites and Al-Zn-Mg alloy was also performed in this study. The weight loss decreased with increasing the volume fraction of alumina and with increasing the magnesium content.
|