The microstructures of components of ZAlSi8Cu3Fe alloy in the process of thixo-diecasting were investigated.The effects of processing conditions on the microstructure of the alloy in the thixo-diecasting procedures of...The microstructures of components of ZAlSi8Cu3Fe alloy in the process of thixo-diecasting were investigated.The effects of processing conditions on the microstructure of the alloy in the thixo-diecasting procedures of original casting billets,remelting billets and casting components were researched,and the morphological evolution of α-particles in the alloy was analyzed quantitatively.The results show that,the microstructure of the original billets poured at 582 ℃ consists of rosette-like primary α-particles;in the procedure of remelting,when the temperature rises over solidus,arms in the rosette-like α-particles begin to fuse off from dendritic branches and after further heating,α-particles surrounded by liquid phase are refined by the diffusion of atoms and rounded owing to the least interface stress and interface energy principles;and in the procedure of thixo-diecasting,the morphologic characteristics of α-particles and the distribution of phases in the structure change greatly for the high shear rate under the restricted area of the ingate.展开更多
The billets of Al-Zn-Mg-Cu-Zr and Al-Zn-Mg-Cu-Zr-0.5Er alloys were prepared by semi-continuous direct chill casting （DCC）.The effects of trace Er on microstructure of Al-Zn-Mg-Cu-Zr alloy under as-cast and homogeniz...The billets of Al-Zn-Mg-Cu-Zr and Al-Zn-Mg-Cu-Zr-0.5Er alloys were prepared by semi-continuous direct chill casting （DCC）.The effects of trace Er on microstructure of Al-Zn-Mg-Cu-Zr alloy under as-cast and homogenization conditions were studied.The results show that the grain morphology is large dendritic structure and the grain size increases obviously by the addition of 0.5% Er.Moreover,most of Er element in the alloy segregates at grain boundary during solidification,resulting in ternary Al8Cu4Er phase.After homogenization,most of the MgZn2 phase at grain boundary has dissolved back to Al matrix in the two alloys.In the Er-containing alloy,the dissolution temperature of Al8Cu4Er phase is about 575 °C.Therefore,the homogenization treatment cannot eliminate Al8Cu4Er phase validity.展开更多
文摘The microstructures of components of ZAlSi8Cu3Fe alloy in the process of thixo-diecasting were investigated.The effects of processing conditions on the microstructure of the alloy in the thixo-diecasting procedures of original casting billets,remelting billets and casting components were researched,and the morphological evolution of α-particles in the alloy was analyzed quantitatively.The results show that,the microstructure of the original billets poured at 582 ℃ consists of rosette-like primary α-particles;in the procedure of remelting,when the temperature rises over solidus,arms in the rosette-like α-particles begin to fuse off from dendritic branches and after further heating,α-particles surrounded by liquid phase are refined by the diffusion of atoms and rounded owing to the least interface stress and interface energy principles;and in the procedure of thixo-diecasting,the morphologic characteristics of α-particles and the distribution of phases in the structure change greatly for the high shear rate under the restricted area of the ingate.
基金Project(50875031) supported by the National Natural Science Foundation of ChinaProject(2005CB623705) supported by National Basic Research Program of China
文摘The billets of Al-Zn-Mg-Cu-Zr and Al-Zn-Mg-Cu-Zr-0.5Er alloys were prepared by semi-continuous direct chill casting （DCC）.The effects of trace Er on microstructure of Al-Zn-Mg-Cu-Zr alloy under as-cast and homogenization conditions were studied.The results show that the grain morphology is large dendritic structure and the grain size increases obviously by the addition of 0.5% Er.Moreover,most of Er element in the alloy segregates at grain boundary during solidification,resulting in ternary Al8Cu4Er phase.After homogenization,most of the MgZn2 phase at grain boundary has dissolved back to Al matrix in the two alloys.In the Er-containing alloy,the dissolution temperature of Al8Cu4Er phase is about 575 °C.Therefore,the homogenization treatment cannot eliminate Al8Cu4Er phase validity.
