Non-isothermal nucleation in strongly supercooled liquids

In a strongly supercooled liquid at a temperature below the unit supercooling, a solid nucleus may grow such that the latent heat of freezing stays essentially within the nucleus. The temperature in the nucleus is then higher than in the surrounding liquid. We investigate the possibility that nucleation there may occur nonisothermally. We conclude that this is generally not the case

Monte Carlo Simulation of a Random-Field Ising Antiferromagnet

Phase transitions in the three-dimensional diluted Ising antiferromagnet in an applied magnetic field are analyzed numerically. It is found that random magnetic field in a system with spin concentration below a certain threshold induces a crossover from second-order phase transition to first-order transition to a new phase characterized by a spin-glass ground state and metastable energy states at finite temperatures.Comment: 10 pages, 11 figure

Some Consequences of Thermosolutal Convection: The Grain Structure of Castings

The essential principles of thermosolutal convection are outlined, and how convection provides a transport mechanism between the mushy region of a casting and the open bulk liquid is illustrated. The convective flow patterns which develop assist in heat exchange and macroscopic solute segregation during solidification; they also provide a mechanism for the transport of dendritic fragments from the mushy region into the bulk liquid. Surviving fragments become nuclei for equiaxed grains and so lead to blocking of the parental columnar, dendritic growth front from which they originated. The physical steps in such a sequence are considered and some experimental data are provided to support the argument

11. 樹枝状結晶成長のシミュレーション(基研研究会「パターン形成,その運動と統計」,研究会報告)

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