وابستگي كمي بين بازوهاي دندريتي و گلبول در ريز ساختار آلياژ AL653 ريخته گري شده در حالت نيمه جامد - نيمه مايع

The quantitative relationship between Dendrite Arm Spacing and globules in semisolid casting of A1356 alloy

One of the most important factors affecting the size and morphology of the globules formed in semisolid casting alloy is the cooling rate of the melt from a superheated temperature down to the mushy zone, influencing the primary Dendrite Arm Spacing (DAS). By shearing the semisolid slurry, the dendrite arms are broken and deformed to rosette type and finally globular shape. In the present investigation the superheated alloy melt has been cooled to the semisolid state by using four different cooling rates. The slurry is then mechanically stirred to gain a globular structure. In order to investigate the effect of cooling rate on the DAS, the semisolid alloy (cooled with four different cooling rates), were quenched in water without stirring and the samples were subjected to metallographic procedures. The relationship between the DAS and globule size has been investigated.