熔体过热度对定向凝固藕状多孔金属结构均匀性的影响（英文）

发布时间：2018-06-28 03:09

本文选题：定向凝固 + 多孔金属　；参考：《Transactions of Nonferrous Metals Society of China》2015年03期

【摘要】：结构均匀性是影响藕状多孔金属的物理和力学性能的重要参数。系统研究熔体过热度对金属-气体共晶定向凝固(Gasar)制备藕状多孔金属的多孔结构均匀性以及气孔率、气孔形貌的影响规律。实验结果表明,凝固过程中存在一临界过热度(△T_c),超过该临界值时,凝固界面前沿熔体中会发生气泡的形核和上浮溢出("冒泡"或"沸腾")现象,结果造成气孔率的下降。另外,过高的过热度会导致相邻气孔的合并粗化,形成大尺寸气泡,最终获得不均匀的气孔结构。在实验结果基础上,建立气泡溢出的临界过热度(△T_c)理论模型和氢气溢出系数计算模型。在考虑氢气溢出时,理论预测的气孔率与实验结果吻合较好。
[Abstract]:Structural homogeneity is an important parameter affecting the physical and mechanical properties of porous metal. The effects of melt superheat on the pore structure uniformity porosity and pore morphology of porous metal prepared by metal-gas eutectic directional solidification (Gasar) were studied systematically. The experimental results show that there is a critical superheat (TSC) in the solidification process. When the critical value is exceeded, the phenomenon of bubble nucleation and floating overflow ("bubbling" or "boiling") will occur in the melt at the front of the solidification interface, resulting in the decrease of the porosity. In addition, excessive superheat will result in the coarsening of adjacent pores and the formation of large size bubbles, resulting in uneven pore structure. On the basis of the experimental results, the theoretical model of critical superheat degree of bubble spillover and the calculation model of hydrogen spillover coefficient are established. When hydrogen spillover is considered, the predicted porosity is in good agreement with the experimental results.
【作者单位】：清华大学材料学院;先进成形制造教育部重点实验室;
【基金】：Project(51271096)supported by the National Natural Science Foundation of China Project(NCET-12-0310)supported by the Program for New Century Excellent Talents in University,Ministry of Education,China
【分类号】：TG249.9;TB383.4

【参考文献】