The samples were fabricated by 220 t thixomolded machine made by Japan Steel Works. The microstructure from the AZ91D magnesium alloy chips to the thixomolded products was investigated. Melting behavior of the chips i...The samples were fabricated by 220 t thixomolded machine made by Japan Steel Works. The microstructure from the AZ91D magnesium alloy chips to the thixomolded products was investigated. Melting behavior of the chips in thixomolding process was analyzed. The evolution processing of solid phase morphology was studied,and evolution model was put forward. The results show that microstructures in outer zone of a chip and the inner zone are obviously different,and the severe distortion takes place in the brim of the chip,where the grains are observed to be bent,distorted,even broken. The severe plastic deformation region is firstly molten,then segregation area in the inner of the chip continues to melt. The liquid phase in solid phase does not formed by liquid entrapped during shearing process,but primarily induced by internal composition segregation.展开更多
Experimental investigation and theoretical analysis of the microstructure of thixomolded AZ91D were carried out to comprehensively understand the morphology transformation of solid particles and the solidification beh...Experimental investigation and theoretical analysis of the microstructure of thixomolded AZ91D were carried out to comprehensively understand the morphology transformation of solid particles and the solidification behavior. Typical microstructure of thixomolded AZ91D is composed of a-Mg and β-Mg17Al12, characterized with aun, aprim and eutectic. Four kinds of aun are classified according to the morphology and generation mechanism, such as spherical （al）, irregular （a2）, entrapping liquid alloy inside （a3） and entrapping pool inside （a4）. Under the effect of heating, shearing, collision, agglomeration or fragmentation, a2 and a4 can be the middle states ofal and a3. Similarly, a4 and a3 can also break into a2 and become al at the end. Controlled by undercooling, aprim nucleates and spherically grows within the remaining liquid alloy of thixomolded AZ91D until instability growth. The investigated microstructure was theoretically proved according to the analysis of Mg-Al binary phase diagram.展开更多
基金Project (2007101) supported by the Science and Technology Development Program of Changchun University of Technology, China
文摘The samples were fabricated by 220 t thixomolded machine made by Japan Steel Works. The microstructure from the AZ91D magnesium alloy chips to the thixomolded products was investigated. Melting behavior of the chips in thixomolding process was analyzed. The evolution processing of solid phase morphology was studied,and evolution model was put forward. The results show that microstructures in outer zone of a chip and the inner zone are obviously different,and the severe distortion takes place in the brim of the chip,where the grains are observed to be bent,distorted,even broken. The severe plastic deformation region is firstly molten,then segregation area in the inner of the chip continues to melt. The liquid phase in solid phase does not formed by liquid entrapped during shearing process,but primarily induced by internal composition segregation.
基金Projects (2006BA104B04-1 2006BAE04B07-3) supported by the National Science and Technology Supporting Program of China+1 种基金Project (2007KZ05) supported by the Science and Technology Supporting Project of Changchun City, ChinaProject supported by the "985 Project" of Jilin University, China
文摘Experimental investigation and theoretical analysis of the microstructure of thixomolded AZ91D were carried out to comprehensively understand the morphology transformation of solid particles and the solidification behavior. Typical microstructure of thixomolded AZ91D is composed of a-Mg and β-Mg17Al12, characterized with aun, aprim and eutectic. Four kinds of aun are classified according to the morphology and generation mechanism, such as spherical （al）, irregular （a2）, entrapping liquid alloy inside （a3） and entrapping pool inside （a4）. Under the effect of heating, shearing, collision, agglomeration or fragmentation, a2 and a4 can be the middle states ofal and a3. Similarly, a4 and a3 can also break into a2 and become al at the end. Controlled by undercooling, aprim nucleates and spherically grows within the remaining liquid alloy of thixomolded AZ91D until instability growth. The investigated microstructure was theoretically proved according to the analysis of Mg-Al binary phase diagram.
