中国铸造2009，Vol.6Issue(2)：115-118,4.
As-cast structure refinement of Ti-46Al alloy by hafnium and boron additions
As-cast structure refinement of Ti-46Al alloy by hafnium and boron additions
摘要
Abstract
The influence of Hf and B on the solidification structure of cast Ti-46Al alloys was investigated. The results show that the coupling effect of Hf and B changes the solidification structure morphology and strongly refines the grain size. When the Hf+B contents were increased from 0 + 0.0 to 3 + 0.2, 5 + 0.6 and 7 + 1.0 (in at. %), the solidification structure morphology changed from coarse columnar dendrite to fine columnar dendrite,then to equiaxed dendrite, and further to fine near granular grain whilst the average grain size decreased to 20 μm.It is concluded that the columnar dendrite refinement is due to the effect of Hf and B on the decrease of Al diffusion coefficient in the melt. The fine near granular grain formation is attributed to the combined constitutional supercooling formed by AI and B segregation that is strengthened by Hf and B additions at the solid/liquid interface uring solidification, and the TiB2 precipitates acting as heterogeneous nuclei.关键词
Hf/B/Ti-46Al alloy/microstructure/diffusion coefficient/heterogeneous nucleiKey words
Hf/B/Ti-46Al alloy/microstructure/diffusion coefficient/heterogeneous nuclei分类
矿业与冶金引用本文复制引用
Zhang Li,Su Yanqing,Yang Huimin,Luo Liangshun,Guo Jingjie..As-cast structure refinement of Ti-46Al alloy by hafnium and boron additions[J].中国铸造,2009,6(2):115-118,4.基金项目
The work was supported by the National Natural Science Foundation of China(507741041)and NCET 05-0350,the program of excellent team in Harbin Institute of Technology. （507741041）
