THE EFFECT OF GROWTH-RATE ON STRUCTURE AN D PROPERTIES OF AGE-HARDENED AL-SI ALLOY

Microstructure and mechanical properties as a function of growth rate of age-hardened Al-9.5Si-0.18Mn-0.19Mg-0.54Fe (wt.%) silumin have been studied. The relation between primary dendrite spacing lambda1 and gr owth rate R in the range of growth rate 2.78 up to 97.2 mum/s was esta blished. Modified Hall-Petch relation was successfully used for expres sion of dependence between ultimate tensile stress and primary dendrit e spacing. Linear dependence between ultimate tensile stress and growt h rate was observed. The different growth rate has a small effect on y ield stress and macrohardness but some effect was found at the relativ ely higher growth rate.