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，通过产生细小的组织、过饱和相、亚稳相和非晶相来产生新的功能性能。为了进一步发展快速凝固工艺，有必要通过引入合适的测量方法来深入了解快速凝固现象，并对现象进行模拟。本研究的目的是：1)定量预测组织形态、相选择和偏析；2)明确发展结构材料和磁性材料快速凝固工艺的指导思想。研究结果如下：1)建立了快速凝固粉末的微观形态和相选择模型，特别是对于具有过冷反应的合金。2)模拟了过冷度、粉末直径和气氛气体与粉末之间的热传递条件下快速凝固粉末的凝固过程。3)结合GET和结晶器表面之间的经验成核方程，建立了晶体生长模型。4)建立了NdFeB磁体的相选择模型。通过对凝固速度和初始成分的控制，确定了初生相Nd2Fe&lt；14&Gt；B的生成条件。5)确定了Nd2FeB磁体的凝固路径。可以预测Nd2Fe&Lt；14&Gt；B和晶界相的数量。

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.