Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第24卷    第10期    总第187期    2014年10月

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文章编号:1004-0609(2014)10-2506-07
热变形粉末冶金Ti-45Al-7Nb-0.3W合金热处理过程的组织演变
赵 堃,刘 咏,黄 岚,刘 彬,李建波,梁霄鹏,贺跃辉

(中南大学 粉末冶金国家重点实验室,长沙 410083)

摘 要: 对锻造态的粉末冶金Ti-45Al-7Nb-0.3W(摩尔分数,%)合金进行后续热处理,研究热处理时间和热处理温度对合金组织演变的影响,利用扫描电镜及透射电镜对合金显微组织进行观察。结果表明:在1230~1260 ℃温度区间热处理可消除锻造态合金的少量β相。在该温度区间进行等时热处理时,随着热处理温度的升高,α晶粒和γ晶粒迅速长大,γ相体积分数急剧减小,且α晶粒趋于等轴化。合金在1260 ℃进行等温热处理时,热处理时间由0.5 h延长至6 h,α晶粒和γ晶粒迅速长大,γ相体积分数降低,继续延长热处理时间,显微组织没有明显的变化。通过计算可知,1260 ℃下α晶粒尺寸的极限值约为0.54 Dγ /Vγ(Dγ为γ晶粒尺寸;Vγ为γ晶粒体积分数)。

 

关键字: TiAl合金;热处理;组织演变;晶粒长大

Microstructure evolution of hot-deformed powder metallurgy Ti-45Al-7Nb-0.3W alloy during heat treatment
ZHAO Kun, LIU Yong, HUANG Lan, LIU Bin, LI Jian-bo, LIANG Xiao-peng, HE Yue-hui

State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

Abstract:Powder metallurgy Ti-45Al-7Nb-0.3W (mole fraction, %) alloy was canned-forged and then heat-treated. The effects of heat treatment time and temperature on the alloy microstructure evolution were studied. The microstructures of as-forged alloy and heat-treated alloy were investigated by scanning and transmission microscopy. The results demonstrate that a few β grains in as-forged alloy are eliminated during heat treatments in the temperature range of 1230-1260 ℃. Isochronal annealing experiments show that the α grain size and γ grain size rapidly increase with increasing the temperature, while the volume fraction of γ phase steeply decreases and α grains become equiaxial. Isothermal annealing experiments at 1260 ℃ for 0.5-6 h reveal a sharp increase of α grain size and γ grain size with time. Meantime, the volume fraction of γ phase decreases. The microstructure of alloy shows no significant change during prolonging the annealing time. By calculation, the extreme α grain size at 1260 ℃ is approximately 0.54 Dγ /Vγ (Dγ is short for γ grain size and Vγ is short or the volume fraction of γ phase).

 

Key words: titanium aluminide alloy; heat treatment; microstructure evolution; grain growth

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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