低温高能球磨Ti／Al复合粉显微组织结构演化

Microstructure Evolution of TiAl Composite Powder during Low Temperature High-Energy Milling

采用低温高能球磨法制备了两种Ti／Al复合粉末，粉末组成为Ti-47Al（at％），Ti-45Al-2Cr-2Nb-1B-0．5Ta（at％）。研究两种粉末在球磨过程中显微组织结构演化、形貌变化。结果表明，降低球磨温度能够有效控制球磨颗粒尺寸，低温条件及合金元素共同作用可以获得高质量的细晶均匀化复合结构粉末。在低温（-140～5）℃不加过程控制剂条件下球磨12h，Ti-45Al-2Cr-2Nb-1B-0．5Ta（at％）粉末粒度得到有效细化，表现出精细均匀化复合结构粉末，Ti与Al晶粒尺寸分别约为16nm，9nm；在相同条件成分为Ti-47Al（at％）球磨5．2h，Ti与Al元素没有很好复合及成分均匀化，两种成分球磨条件下均未有新相生成。在不加过程控制剂条件下，低温环境球磨和合金元素添加对机械合金化过程具有十分重要影响。

Microstructures and morphologies of two kinds of powders Ti-47Al（at%） and Ti-45Al-2Cr-2Nb-1B-0.5Ta（at%） PREPARED by high-energy mechanical alloying at low-temperature were investigated. The results show that the particle size can be effectively controlled by decreasing of the milling temperature and that high quality fine and uniform powders with composite structure can be gained by mutual acting of low temperature condition and alloy elements. The particle size of Ti-45Al-2Cr-2Nb-1B-0.5Ta after milling 12 h at low temperature （-140-5）℃ without process control agent can be effectively refined to get fine and uniform powders with composite structure. The grain sizes of Ti an Al are about 16 nm and 9 nm, respectively. However, Ti and Al in Ti-47Al （at%） after milling 5.2 h at the same conditions are far from composite and component uniform. No new phase was found at the milling conditions in the two constitutions. Low temperature and alloy element play an important role in mechanical alloying without process control agent.