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10卷    第6期    总第39期    2000年12月

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文章编号:1004-0609(2000)06-0779-06
Ti-48Al合金全片层组织的稳定性
李臻熙, 孙福生, 曹春晓

(北京航空材料研究院, 北京 100095)

摘 要:    研究了Ti48Al合金全片层组织在1 150 ℃时效时的组织稳定性。结果表明,1 400 ℃,1 h固溶处理后炉冷获得的粗片层组织的稳定性远远优于空冷获得的细片层组织。细片层组织首先在晶界处发生不连续粗化,而后粗化片层组织中的 α2相发生溶解并球化,从而转变为近 γ 组织;空冷组织中魏氏片层的存在降低了片层组织的稳定性,魏氏片层/基体界面与晶界一同成为片层组织发生分解的起始部位。Ti48Al+0.8%B(摩尔分数)合金的细片层组织因晶界TiB2相的存在有效抑制了晶界不连续粗化,但 γ 相从TiB2/基体界面和晶界重新形核生长使片层组织转变为均匀的细晶近γ组织。

 

关键字:   TiAl合金; 片层组织;稳定性; 不连续粗化

Thermal stability of fully lamellar microstructures in Ti48Al alloy
LI Zhenxi, SUN Fusheng, CAO Chunxiao

Beijing Institute of Aeronautical Materials, Beijing 100095, P.R.China

Abstract:The thermal stability of fully lamellar microstructures of Ti48Al alloy after aging at 1 150 ℃ was studied. The thermal stability of coarse lamellar microstructure produced by heattreatment at 1 400 ℃ for 1 h, followed by furnace cooling is superior to that of the fine lamellar microstructure produced by air cooling. During the aging, the discontinuous coarsening (DC) occurs at the grainboundaries of the fine lamellar microstructure, then α2 phase of the coarsened lamellar microstructures dissolves and spheroidizes. Ultimately, the fine lamellar microstructure transforms into the near gamma microstructure. The Widmanstatten lamellar colonies produced by air cooling from the α  single phase field degrade the thermal stability of the fine lamellar microstructure, the decomposition of the fine lamellar microstructure initiates at the Widmanstatten lamellar/matrix interfaces and grain boundaries. The TiB2 particles at grain boundaries in Ti48Al +0.8%B (mole fraction) alloy restrain the discontinue coarsening effectively. However, the new γ grains nucleate and grow at the TiB2/matrix interfaces and grain boundaries. As a result, the fine lamellar microstructure transforms into the homogeneous and fine near gamma microstructure.

 

Key words: TiAl alloy; lamellar microstructure; thermal stability; discontinuous coarsening

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

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

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