Effects of minor B, Y and Cooling Rate on the Microstructure Refinement of Ti-47Al-2Cr-2Nb Alloy

Wang Jianji1; Yang Lili1; Zheng Lijing1; Yan Jie1; Xiao Zhixia1; Li Guoqiang2; Zhang Hu1

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Effects of minor B, Y and Cooling Rate on the Microstructure Refinement of Ti-47Al-2Cr-2Nb Alloy
Vol. 31, Issue 3, Pages: 260-263(2011)
Published： 2011 ，
DOI：

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[1]王建吉,杨莉莉,郑立静,闫洁,肖志霞,李国强,张虎.B、Y及冷却速度对Ti-47Al-2Cr-2Nb合金组织的细化作用[J].特种铸造及有色合金,2011,31(03):260-263+193-194.

Wang Jianji1, Yang Lili1, Zheng Lijing1, et al. Effects of minor B, Y and Cooling Rate on the Microstructure Refinement of Ti-47Al-2Cr-2Nb Alloy. [J]. Special Casting & Nonferrous Alloys 31(3):260-263(2011)
[1]王建吉,杨莉莉,郑立静,闫洁,肖志霞,李国强,张虎.B、Y及冷却速度对Ti-47Al-2Cr-2Nb合金组织的细化作用[J].特种铸造及有色合金,2011,31(03):260-263+193-194. DOI：

Wang Jianji1, Yang Lili1, Zheng Lijing1, et al. Effects of minor B, Y and Cooling Rate on the Microstructure Refinement of Ti-47Al-2Cr-2Nb Alloy. [J]. Special Casting & Nonferrous Alloys 31(3):260-263(2011) DOI：

摘要

研究了微量元素B、Y和冷却速度对Ti-47Al-2Cr-2Nb合金组织的复合细化效果。结果表明

在水冷铜坩埚磁悬浮真空感应熔炼和Y2O3型壳精密铸造条件下

B元素能够有效细化Ti-47Al-2Cr-2Nb铸件的晶粒尺寸

使其由粗大的柱状晶变为细小的等轴晶组织

但没有起到细化片层间距的明显作用。B、Y复合细化可以在B元素细化效果的基础上进一步细化片层团尺寸

同时显著细化片层间距。在壁厚为2～20mm范围内

Ti-47Al-2Cr-2Nb-0.8B-0.3Y铸件的宏观组织均为等轴晶;且随着厚度的增加

等轴晶尺寸逐渐增大。适当降低型壳预热温度也有助于获得细小的片层组织。

Abstract

Effects of minor B and Y as well as cooling rate on compound refinement of microstructure of Ti+47Al-2Cr-2Nb alloy were investigated. The results show that in the condition of smelting with the water-cooled copper crucible vacuum induction skull furnace and investment casting with Y2O3 shell mold

grain size of Ti-47Al-2Cr-2Nb castings is greatly refined with B addition

where coarse columnar grain is converted into fine equaixed one

however

refining effects on lamellar spacing are absent. B and Y compound refinement can not only further effectively refine grain size

but also significantly refine the lamellar spacing. Macro-structure of Ti-47Al-2Cr-2Nb-0.8B-0.3Y alloy castings exhibits equiaxed grain with different thickness from 2 mm to 20 mm

meanwhile

with increasing in thickness of the castings

equiaxed grain size is gradually coarsened. It is beneficial for obtaining fine lamellar structure with proper decrease of pre-heating temperature of mold shell.