Abstract: Structural evolutions of ZL112Y die cast alloy in procedures of semi-solid die-casting were investigated. The structures of solid α phase of original billet, semi-solid remelting billet after quenching in water, pierce block in the chamber of die-casting machine, ingate block in die cast mould and specimens at different locations in a semi-solid die cast component were observed. Meanwhile, the circularity of α particles, mean equivalent diameter of α particle, volume fraction of α solid phase, numbers of α particles were measured by the quantity analysis of metallography. The results show that, 1)dendritical colonies of α phase in original billet change into isolated grains with forms of nodules and granule, owing to the dendrite fusing-off mechanism of alloys at heating up to semi-solid temperatures, and the semi-solid billet has a thixotropy property and can be used to form component in die casting; 2)the motion of the billet in squeezing chamber in die cast machine minimizes heterogeneity of sizes of α particles and refines dendrites further that are remained during semi-solid remelting; and 3)liquid phase more easily arrives at the end of the component than solid α particle as homogenized and refined semi-solid slurry enters the cavity of die-casting mould, therefore, in the location in a component far from ingate the number of solid α particles is less than that near ingate.
Structural evolutions of ZL112Y alloy in procedures of semi-solid die-casting
Abstract：
Structural evolutions of ZL112Y die cast alloy in procedures of semisolid diecasting were investigated. The structures of solid α phase of original billet, semisolid remelting billet after quenching in water, pierce block in the chamber of diecasting machine, ingate block in die cast mould and specimens at different locations in a semisolid die cast component were observed. Meanwhile, the circularity of α particles, mean equivalent diameter of α particle, volume fraction of α solid phase, numbers of α particles were measured by the quantity analysis of metallography. The results show that, 1)dendritical colonies of α phase in original billet change into isolated grains with forms of nodules and granule, owing to the dendrite fusingoff mechanism of alloys at heating up to semisolid temperatures, and the semisolid billet has a thixotropy property and can be used to form component in die casting; 2)the motion of the billet in squeezing chamber in die cast machine minimizes heterogeneity of sizes of α particles and refines dendrites further that are remained during semisolid remelting; and 3)liquid phase more easily arrives at the end of the component than solid α particle as homogenized and refined semisolid slurry enters the cavity of diecasting mould, therefore, in the location in a component far from ingate the number of solid α particles is less than that near ingate.
