Solidification In Magnetic Field Research Articles

Mathematical model and numerical simulation of aluminum casting and solidification in magnetic fields with allowance for free surface dynamics

A complex mathematical model of aluminum casting and solidification in a variable electromagnetic field is constructed. The model is based on the solution of magnetohydrodynamic equations and the VOF method. Test results are presented for the model and the numerical algorithm proposed. The numerical results are compared with experimental data and computations of other authors and are found to be in good agreement. The model is used to simulate aluminum solidification under an electromagnetic field. The physical processes influencing ingot formation are analyzed.

Three-Dimensional Gravity-Jitter Induced Melt Flow and Solidification in Magnetic Fields

A full three-dimensional transient numerical model is presented for gravity- ( g-) jitter induced melt e ow and solidie cationphenomenawithandwithoutexternallyappliedmagnetice eldsduringthemeltgrowthofSn-dopedBi singlecrystalsin microgravity.Themodel isdeveloped basedonaEulerian‐ Lagrangian e niteelementformulation, coupled with a mesh-deforming algorithm to track the solidie cation front. Extensive numerical simulations are carriedout,andthestudiedparametersincludesoluteconcentration-dependentmeltingtemperature,solidie cation interface morphology, magnetic e eld direction and magnitude, idealized microgravity condition, and synthesized and real g-jitter data conditions. Computed results show that g-jitter induced melt e ow is time dependent and exhibits a complex three-dimensional structure and that the e ow can have detrimental effects on solute concentration distribution. The g-jitter induced melt e ow and its deleterious effects on solidie cation can be suppressed by externally applied magnetic e elds. The three-dimensional numerical simulations suggest that a two-dimensional model is useful in providing some essential features of g-jitter induced e ow and solidie cation behavior with and without externally applied magnetic e elds and that a three-dimensional model is required to resolve fully the complex spatial e ow structure when all g-jitter components are operative during a realistic space e ight.

Synthesis of Tb 0.3Dy 0.7Fe 1.9 magnetostrictive alloy by unidirectional solidification in magnetic field and microgravity

We performed unidirectional solidification experiments on magnetostrictive materials of Tb 0.3Dy 0.7Fe 2− x , (Terfenol-D) alloy in a static magnetic field from 0 to 0.1 T and microgravity of 10 −4 g for 10 s. When the magnetic field strength was increased from 0 to 3.7×10 −2 T during unidirectional solidification in microgravity, a [1 1 1] crystallographic alignment of the grains dominated, and the maximum magnetostriction increased from 500 to 2000 ppm. However, when a magnetic field above 3.7×10 −2 T was applied during solidification, magnetostriction decreased to 1000 ppm because cracks were formed. For comparison, unidirectional solidification under field of 3.7×10 −2 T in normal gravity yields a maximum magnetostriction of 1000 ppm.

微小重力環境を利用する材料開発

The advantages of working in a microgravity (μg) environment are the lack of gas or liquid mass transfer by convection, the clearly apparent surface tension of liquids, the homogeneous mixing of substances with different specific gravity, and ease of containerless processing. Spherical semiconductor single crystals such as InSb and Ge, nano-materials of SiGe and β-FeSi2 and materials with controlled structure such as magnetostrictive materials, TbFe2 and (Tb0.3Dy0.7)Fe2-X, could be synthesized by containerless solidification, splat solidification from homogeneous melts and unidirectional solidification in magnetic fields in microgravity, respectively.