Development at temperature mrasurment system and solidification microstructure control under rapid solidification condition

快速凝固工艺有望发展新的近净成形方法，并通过制造精细组织、过饱和相、亚稳态相和非晶态相来产生新的功能特性。为了进一步发展快速凝固工艺，有必要深入了解快速凝固现象，引入适当的测量方法，并对快速凝固现象进行模拟。本研究的目的是：(1)定量预测形貌、相选择和偏析；(2)为发展组织材料和磁性材料的快速凝固工艺提供明确的指导方针。所得结果如下：1)建立了形貌和相选择，特别是对具有完美反应的合金。2)在过冷、粉末直径和环境气体与粉末之间的传热条件下，模拟了快速凝固粉末的凝固过程。3)结合结晶器与结晶器表面之间的经验成核方程，建立了结晶生长模型。4)建立了Nd-Fe-B磁体的相选择模型。通过控制凝固速率和初始成分，建立了生成初生相Nd_2Fe_<14>B的条件。5)建立了钕铁硼磁体的凝固路径。可以预测Nd_2Fe_<14>B和边界相的数量。

Rapid solidification processing is expected to develop new near net shape methods and to bring out new functional properties by making fine structures, supersaturation, metastableand amorphous phases. To develop further rapid solidification processing, it is necessary to under stand deeply rapid solidification phenomenaby introducing appropriate measuring methods and also to simulate phenomena. This research is aimed 1) to predict quantitatively morphology and phase selection, and segregation, 2) to make clear a guide line to develop the rapid solidification processing of structural and also magnetic materials. Results obtained are as follows ;1) Morphology and phase selection are established, especially for alloys with peretectic reactions.2) Solidification of rapidly solidified powders is simulated under the conditions of undercooling, diameter of powders and heat transfer between ambientgas and powders.3) Crystal growth model is developed by incorporating empirical nucleationequations occurred between in got and mold surfaces.4) Phase selection is modeled for Nd-Fe-B magnets. The condition of producing primary phase Nd_2Fe_<14>B is established controlling solidification rate and initial composition.5) Solidfication path is established for Nd-Fe-B magnets. The amount of Nd_2Fe_<14>B and boundary phases can be predicted.