Ti-48Al合金全片层组织的稳定性
来源期刊：中国有色金属学报2000年第6期
论文作者：李臻熙 孙福生 曹春晓
文章页码：779 - 784
关键词：TiAl合金； 片层组织；稳定性； 不连续粗化
Key words：TiAl alloy； lamellar microstructure； thermal stability； discontinuous coarsening
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。
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 heattreatment 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.
