Abstract In the present work, the initial precipitation behavior of nitrides in TiAl alloys was investigated by monitoring the morphology, distribution, crystallographic orientation relationship and interface atomic structure of the nitride precipitates using TEM and HRTEM. It is found that there are two kinds of nitride precipitates (Ti2AlN and Ti3AlN) forming in the initial precipitation stage of Ti-49Al-1N alloys. The rod-like Ti2AlN precipitates tend to distribute at γ(TiAl)/α2(Ti3Al) interface with the crystallographic orientation relationship of [11 2 ‾ 0]Ti3Al//[11 2 ‾ 0]Ti2AlN//[ 1 ‾ 01]TiAl, (0001)Ti3Al//(0001)Ti2AlN//(111)TiAl. Both the Ti3Al(0001)/Ti2AlN(0001) interface and Ti2AlN(0001)/TiAl(111) interface display a plane-to-plane matching with coherent atomic correspondence. The plate-like Ti3AlN precipitates tend to distribute in the γ(TiAl) matrix with the crystallographic orientation relationship of [ 1 ‾ 10]Ti3AlN//[ 1 ‾ 10]TiAl, (111)Ti3AlN//(111)TiAl. The Ti3AlN(111)/TiAl(111) interface displays an edge-to-edge matching with coherent atomic correspondence. The morphology, distribution, crystallographic orientation relationship and interface atomic structure of nitride precipitates are determined by the crystal structure and lattice misfit of nitride precipitates and matrix. The understanding here will be useful in guiding morphology design and dispersion controlling of the nitride precipitates in TiAl alloys, and will further be benefit for improving the mechanical properties of TiAl alloys.

中文翻译：

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TiAl合金中氮化物初始析出行为的原子尺度研究

摘要 在目前的工作中，通过使用 TEM 和 HRTEM 监测氮化物析出物的形貌、分布、晶体取向关系和界面原子结构，研究了 TiAl 合金中氮化物的初始析出行为。结果表明,Ti-49Al-1N合金在初始析出阶段有两种氮化物析出物(Ti2AlN和Ti3AlN)形成。棒状Ti2AlN析出物倾向于分布在γ(TiAl)/α2(Ti3Al)界面，晶体取向关系为[11 2 ‾ 0]Ti3Al//[11 2 ‾ 0]Ti2AlN//[ 1 ‾ 01]TiAl , (0001)Ti3Al//(0001)Ti2AlN//(111)TiAl。Ti3Al(0001)/Ti2AlN(0001) 界面和 Ti2AlN(0001)/TiAl(111) 界面都显示出具有相干原子对应的平面到平面匹配。片状Ti3AlN析出物倾向于分布在γ(TiAl)基体中，晶体取向关系为[1‾10]Ti3AlN//[1‾10]TiAl、(111)Ti3AlN//(111)TiAl。Ti3AlN(111)/TiAl(111) 界面显示了具有相干原子对应的边对边匹配。氮化物析出物的形貌、分布、晶体取向关系和界面原子结构由氮化物析出物与基体的晶体结构和晶格错配决定。本文的认识将有助于指导TiAl合金中氮化物析出物的形貌设计和分散控制，进一步有利于提高TiAl合金的力学性能。Ti3AlN(111)/TiAl(111) 界面显示了具有相干原子对应的边对边匹配。氮化物析出物的形貌、分布、晶体取向关系和界面原子结构由氮化物析出物与基体的晶体结构和晶格错配决定。本文的认识将有助于指导TiAl合金中氮化物析出物的形貌设计和分散控制，进一步有利于提高TiAl合金的力学性能。Ti3AlN(111)/TiAl(111) 界面显示了具有相干原子对应的边对边匹配。氮化物析出物的形貌、分布、晶体取向关系和界面原子结构由氮化物析出物与基体的晶体结构和晶格错配决定。本文的认识将有助于指导TiAl合金中氮化物析出物的形貌设计和分散控制，进一步有利于提高TiAl合金的力学性能。氮化物析出物的晶体取向关系和界面原子结构由氮化物析出物与基体的晶体结构和晶格错配决定。本文的认识将有助于指导TiAl合金中氮化物析出物的形貌设计和分散控制，进一步有利于提高TiAl合金的力学性能。氮化物析出物的晶体取向关系和界面原子结构由氮化物析出物与基体的晶体结构和晶格错配决定。本文的认识将有助于指导TiAl合金中氮化物析出物的形貌设计和分散控制，进一步有利于提高TiAl合金的力学性能。