Effect of carbon addition on the microstructures and mechanical properties of gamma-TiAl alloys
Effect of carbon addition on the microstructures and mechanical properties of gamma-TiAl alloys
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DOI：
10.1016/s0966-9795(96)00086-6
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发表时间：
1997-01-01
期刊：
影响因子：
4.4
通讯作者：
Nemoto, M
中科院分区：
文献类型：
--
作者：
Tian, WH;Nemoto, M
研究了碳对TiAl金属间化合物合金显微组织和力学性能的影响。结果表明，碳不仅是TiAl中有效的固溶强化剂，而且通过碳化物的弥散分布，也是一种有效的析出强化剂。透射电子显微镜观察表明，掺碳TiAl合金从1523 K淬火后，在1073 K左右时效时出现细小的针状析出物，这些析出物只存在于平行于（001）轴的一个方向上。选区电子衍射分析表明，针状沉淀物是钙钛矿型，Ti 3AlC（P相）。P相与TiAl基体的取向关系为（001）（P）//（001）TiAl和（010）（P）//（010）（TiAl）。通过在较高温度下或在1073 K下进行较长时间的时效，在TiAl基体的{111}面上形成具有六方晶体结构的Ti 2AlC（H相）的板状析出物。H相与TiAl基体之间的取向关系为（0001）（H）//（111）（TiAl）和（）（H）//（）（TiAl）。碳掺杂的TiAl由于碳化物的细小析出而明显硬化。偏离化学计量比对TiAl合金的时效行为有显著影响。细小碳化物的析出使TiAl的高温强度明显提高。在更高的温度下，位错绕过碳化物针状物。Orowan应力的计算结果与实验测量结果吻合较好。(C)1997年爱思唯尔科学有限公司。
The effect of carbon addition on the microstructures and mechanical properties of TiAl intermetallic alloys has been characterized. It is shown that carbon is not only an efficient solid solution strengthener in TiAl, it is also an efficient precipitation strengthener by fine dispersion of carbide. Transmission electron microscope observations have revealed that fine needle-like precipitates, which lie only in one direction parallel to the (001) axis, appear in carbon doped TiAl during aging at temperatures around 1073 K after quenching from 1523 K. Selected area electron diffraction analyses have shown that the needle-shaped precipitate is of a perovskite type, Ti3AlC (P-phase). The orientation relationship between the P-phase and the TiAl matrix is found to be (001)(P)//(001)TiAl and (010)(P)//(010)(TiAl). By aging at higher temperatures or for longer periods at 1073 K, plate-like precipitates of Ti2AlC (H-phase) with a hexagonal crystal structure are formed on the {111} planes of the TiAl matrix. The orientation relationship between the H-phase and the TiAl matrix is (0001)(H)//(111)(TiAl) and ()(H)//()(TiAl). TiAl doped with carbon hardens appreciably by the fine precipitation of carbide. The deviation from the stoichiometry has a significant effect on the aging behavior of TiAl. High temperature strength of TiAl increases appreciably by the precipitation of fine carbide. Dislocations bypass the carbide needles at further higher temperatures. The calculation of Orowan stress shows a good agreement with the experimentally measured result. (C) 1997 Elsevier Science Limited.