Research Abstract |
1.Periodic structure formation during unidirectional solidification During unidirectional solidification of peritectic alloys, periodic structures in which faction of two constituent phases fluctuates in the growth direction have been observed. This study performed unidirectional solidification under a magnetic field up to 10T and indicated that the periodic structure was preferably observed by reducing convection. The results indicated that the periodic systems involved the periodic growth mode. 2.Aligned structure formation due to the magnetic anisotropy This study developed novel processing to obtain the magnetically aligned structure. In the alignment orocedures, non-equilibrium structure produced by rapid solidification was used as a starting material. Ieating the non-equilibrium structure of Bi-Mn system caused the semisolid state, while can be obtained during conventional solidification procedure. By imposing the magnetic field on the semisolid state, alignment of the BiMn compound
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were achieved. Furthermore, the aligned structure of BiMn was obtained during coarsening under a magnetic field. This study proposed mechanism of the alignment by using the non-equilibrium structure. 3.Control of solidified structure of monotectic alloys There is immiscibility gap of liquid state for monotectic alloys. In general, it is difficult to obtain uniform and fine solidified structure, since density difference between the two liquid phases initiates strong convection and leads to macrosegregation. This study indicated that imposition of a magnetic fleld, 10T, significantly reduced convection and consequently produced homogenous solidified structure for Cu-Pb alloys. In the case of unidirectional solidification for Al-In alloys, rod-type monotectic structure, which was basically similar to the regular eutectic structure, was obtained by imposing a magnetic field more than 2T. Imposition of the high magnetic fields was effective to obtain homogenous solidified structure for monotectic systems. Less
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