新型高温高Nb-TiAl多孔材料的孔隙形成与相变交互作用机制

新型高Nb-TiAl金属间化合物多孔材料，能较好解决普通金属的高温抗氧化和抗酸碱腐蚀性能差、陶瓷多孔材料难以焊接组件化和强度较差等难点，并可以采用传统的粉末冶金技术制备，因此在常温和高温过滤以及高温隔热等领域具有广泛的应用前景。本基金提出高Nb-TiAl多孔材料的孔隙形成不但是Kirkendall扩散效应造成，而是与相变过程紧密相关，两者交互作用。通过制备过程各阶段的不同尺度孔隙的形成机制及影响因素和Nb元素对于在高温相变过程对微观孔隙演变过程的影响规律关键科学问题的解决，探索孔隙形成过程与相变过程的联系，得出孔隙形成与相变交互作用机制，最终得到影响孔隙孔径分布、孔隙率以及孔隙形貌的决定因素和定量关系。这既丰富有序金属间化合物多孔材料的孔隙生长机制的理论，又将会指导该类金属间化合物多孔材料的孔隙控制和设计，对开发不同功能的新型金属间化合物多孔材料具有重大意义。

The newly developed high-temperature high Nb-TiAl porous intermetallics prepared by powder metallurgy, could avoid poor high-temperature oxidation resistance and poor corrosion resistance of conventional porous metals, and poor weldability and lower strength of porous ceramics. Therefore, this kind of porous intermetallics has broad application prospects in the fields of room/high-temperature filtration, high-temperature insulation and so on. This project suggests that that the pore-formation of high Nb-TiAl porous materials mainly results from an interaction of Kirkendall effect and phase transformation, and two key scientific issues are needed to be solved: the formation mechanism of different-scale pores at different temperature stages and the effect of Nb addition on the pore formation in the high-temperature phase transformation process. These researches are beneficial for exploring the relationship and interaction mechanism between pore-formation and transformation process, and getting the determinants and quantitative relationships of pore size distribution, porosity, and pore morphology. The results could both enrich the theory of pore-formation mechanism of porous ordered intermetallics, and guide the direction of pore control and design of porous intermetallic materials. It has great significance on the development of newly porous intermetallics for different applications and requirements.