TiAl基合金片层结构粗化行为研究进展

Lamellar structure is the most important microstructure in TiAl alloy. In the present paper, we firstly summarized the research progress of coarsening of lamellar structure in TiAl alloy so far, and introduced the two types of the lamellar coarsening: continuous and discontinuous coarsening in TiAl lamellar structure. Then we analyzed thermodynamic driving force source, including chemical volume free energy, interface energy, elastic strain energy and grain boundary energy of lamellar coarsening. In addition, we also described the dynamic characteristic of lamellar coarsening and discussed the influence factors of lamellar coarsening, including temperature, time, condition of microstructure, alloy elements and so on. On this basis, we studied the lamellar coarsening of Ti-4822 alloy, described and analyzed its continuous and discontinuous coarsening of lamellar structure at elevated temperature and its change with temperature and time. Finally, we found that the two coarsening types compete obviously at 1160℃. Discontinuous coarsening dominates at about eutectoid temperature while continuous coarsening dominates at higher temperature (above 1200℃) and discontinuous coarsening is suppressed.