Development of direct observation method of solidification behavior by using X-ray

(A)铸造凝固过程数值模拟的发展本课题在研究之初，分析了充型过程所要解决的问题，重点研究了在合理的计算时间内，为铸造工程提供可靠结果的模拟方法，以减少计算时间，改善型内流动形态，引入了“规则单元和非规则混合单元”，建立了计算流体流动的算法。采用“混合单元”法，可以在不增加计算时间的情况下，较好地计算形状较为复杂的结晶器内的流体流动。该方法也被应用于铸件的三维模拟。并将计算结果与X射线观测结果进行了比较，验证了计算方法的有效性。(B)利用同步辐射装置（SPring8）的微焦点X射线源，发展了铸造和凝固过程的直接观察方法。利用微焦点X射线装置对结晶器内的流动形态进行了观察，为数值模拟的发展提供了有用的信息。利用同步辐射X射线和高分辨率二维探测器对铝合金铸件中的气孔形成进行了原位观察。还观察到Sn基合金凝固组织的发展。

(A) Development of numerical simulation of casting and solidificationAt the beginning of this research project, problems to be solved for the mold filling process were analyzed and this project focused on the simulation method that provided reliable results for the foundry engineering within reasonable calculation time, to reduce the calculation time and to improve flow pattern in the mold, "regular and irregular-mixed elements" were introduced and the algorism to calculate fluid flow was established. By using the "mixed elements"method, fluid flow in the mold with rather complex shape can be well calculated without increase o* the calculation time. the method was also applied to three-dimensional simulation of the castings. the calculate results of fluid flow were compared with the flow pattern observed by using the X-ray observation developed in this study in order to confirm the validity of the calculation method.(B) Direct observation using X-rayDirect observation method of the casting and solidification was developed by using the micro-focus X-ray source an synchrotron radiation facility (SPring8). Flow pattern in the mold was well observed by using the micro-focus X-ray apparatus, providing useful information for the development of the numerical simulation. Formation of porosities in the Al-alloy castings were in-situ observed by using the synchrotron radiation X-ray and high resolution 2D detector. Development of the solidified structure in the Sn based alloys was also observed.