The microstructural formation of the semi-solid AlSi7Mg alloy stirred by electromagnetic field is investigated together withthe tempeatre field of the stirred melt at continuously cooling. A impoat kinetic factor for ...The microstructural formation of the semi-solid AlSi7Mg alloy stirred by electromagnetic field is investigated together withthe tempeatre field of the stirred melt at continuously cooling. A impoat kinetic factor for primny a-Al nucleation is proposed. It isfound that a low temperatUre gradient exists in the electromagnetic stirred melt. This is why the first dendritic arms and secondary de-ndritic arms are refmed. Experimefltal results also show that the root remelting of secontw dendritic arms is an twortat mechanismfor the primary α-Al refmement. Strong electromagnetic stirring greatly reduces the composition supercooling in the melt and eliminatesprefedrig growth of the first dendritic arms. Therefore, many rosettes or spherical Primary α-Al phase particles form finally.展开更多
The effect of the solidification conditions on the microstructures was studied during partial remelting of AlSi7Mg alloy with the help of an electrical pipe-type fumace. The results show that the eutectic is remelted ...The effect of the solidification conditions on the microstructures was studied during partial remelting of AlSi7Mg alloy with the help of an electrical pipe-type fumace. The results show that the eutectic is remelted above all and α phases are gradually evolved into spheroidal shape,if the AlSi7Mg alloys shrmd strongly by rotating electromagnetic field during the first solidification are heated again to 589 or 597℃ and have been held for a short time (for example, 5~10 min), and moreover, the higher the holding temperature,the faster the eutectic remelting process and α phase's evolution are. In contrast even though the AlSi7Mg alloy's samples non-stirred with fine dendritic microstructures are heated to the same temperatures as those stirred by rotating electromagnetic field and have been held for 60 min,it is not possible to change all the dendritic a phases to speroidal α phase.展开更多
The microstructural evolution during partial remelting of dendritic AlSi7Mg alloys was studied with the help of an electrical fumace. The results show that it is difficult to change all the primary a dendrites into th...The microstructural evolution during partial remelting of dendritic AlSi7Mg alloys was studied with the help of an electrical fumace. The results show that it is difficult to change all the primary a dendrites into the spheroidal a phases, when the dendritic samples of AlSi7Mg alloy are remelted under 589 or (597±1)℃ and held on mis condition for 5 to 120 min. The results also show that the samples remelted can be deformed under the heavy force, if the holding time is longer under higher temperature.展开更多
文摘The microstructural formation of the semi-solid AlSi7Mg alloy stirred by electromagnetic field is investigated together withthe tempeatre field of the stirred melt at continuously cooling. A impoat kinetic factor for primny a-Al nucleation is proposed. It isfound that a low temperatUre gradient exists in the electromagnetic stirred melt. This is why the first dendritic arms and secondary de-ndritic arms are refmed. Experimefltal results also show that the root remelting of secontw dendritic arms is an twortat mechanismfor the primary α-Al refmement. Strong electromagnetic stirring greatly reduces the composition supercooling in the melt and eliminatesprefedrig growth of the first dendritic arms. Therefore, many rosettes or spherical Primary α-Al phase particles form finally.
文摘The effect of the solidification conditions on the microstructures was studied during partial remelting of AlSi7Mg alloy with the help of an electrical pipe-type fumace. The results show that the eutectic is remelted above all and α phases are gradually evolved into spheroidal shape,if the AlSi7Mg alloys shrmd strongly by rotating electromagnetic field during the first solidification are heated again to 589 or 597℃ and have been held for a short time (for example, 5~10 min), and moreover, the higher the holding temperature,the faster the eutectic remelting process and α phase's evolution are. In contrast even though the AlSi7Mg alloy's samples non-stirred with fine dendritic microstructures are heated to the same temperatures as those stirred by rotating electromagnetic field and have been held for 60 min,it is not possible to change all the dendritic a phases to speroidal α phase.
文摘The microstructural evolution during partial remelting of dendritic AlSi7Mg alloys was studied with the help of an electrical fumace. The results show that it is difficult to change all the primary a dendrites into the spheroidal a phases, when the dendritic samples of AlSi7Mg alloy are remelted under 589 or (597±1)℃ and held on mis condition for 5 to 120 min. The results also show that the samples remelted can be deformed under the heavy force, if the holding time is longer under higher temperature.
