摘要
The in-situ micro-nano Ti_(2)AlC particles reinforced TiAl(Ti_(2)AlC/TiAl)composite was fabricated using spark plasma sintering.The hot workability of Ti_(2)AlC/TiAl composite was studied,and the effect of micro-nano particles on flow stress and dynamic recrystallization of composite was discussed.The results showed that the micro-nano Ti_(2)AlC particles included strengthening and softening effects during hot deformation,resulting in the fact that the Ti_(2)AlC/TiAl composite exhibited a higher flow stress and more sufficient dynamic recrystallization.The strengthening effect was mainly attributed to the Ti_(2)AlC particles induced refinement strengthening and hindered dislocation motion at the initial stage.Moreover,the precipitation of nano-TiCr2 particles induced by stress concentration during hot deformation also contributed to higher flow stress via impeding dislocation motion.Meanwhile,the refined microstructure and dislocation pile-up caused by micro-nano particles during deformation provided more nucleation sites for dynamic recrystallization,which significantly promoted the dynamic recrystallization of the second stage.The present results reveal that the Ti_(2)AlC/TiAl composite exhibited excellent hot workability,which is important to promote the application of TiAl alloys.
利用放电等离子烧结技术原位合成微纳米Ti_(2)AlC颗粒增强的TiAl复合材料(Ti_(2)AlC/TiAl)。研究了Ti_(2)AlC/TiAl复合材料的热加工性能,讨论了微纳米颗粒对复合材料流变应力和动态再结晶的影响。结果表明,微纳米Ti_(2)AlC颗粒在热变形过程中同时具有强化效应和软化效应,最终导致Ti_(2)AlC/TiAl复合材料呈现出更高的流变应力和更充分的动态再结晶。变形初期,微纳米Ti_(2)AlC颗粒细化组织和阻碍位错滑移引起强化效应。此外,变形过程中应力集中诱导了纳米TiCr2相的析出,进一步阻碍位错滑移导致更高的流变应力。另一方面,组织的细化和微纳颗粒在变形过程中引起的位错塞积为动态再结晶提供了更多的形核位点,显著促进了变形第二阶段的动态再结晶。研究表明,Ti_(2)AlC/TiAl复合材料具有优异热加工性能,对促进TiAl合金应用具有重要意义。
基金
supported by the National Natural Science Foundation of China(No.52001262)
the Natural Science Foundation of Zhejiang Province,China(No.LZY22E010001)
the Natural Science Foundation of Shaanxi Province,China(No.2020JC-50)。
