Abstract

The composition and crystal structure of compounds produced by self-propagating high-temperature synthesis (SHS) from the 5Ta–2Ni–3Al (at %) powder mixture followed by vacuum remelting at 3000°C are studied. The SHS product contains the following phases: TaNiAl (Laves τ₁ phase), NiAl, Ni₂Al₃, and Ta. Its microstructure includes Ta₈₅Ni₇Al₈, Ta₅₂Ni₂₀Al₂₈, and Ta₅₃Ni₂₅Al₂₂ ternary phases according to elemental analysis data. Reflections belonging to no known ternary phases in the Ta–Ni–Al system under consideration are revealed in the X-ray diffraction pattern of the remelted material. Based on the homological approach, it is found that these reflections belong to three phases with the structural types W₆Fe₇ (\(R\bar {3}m\)), Ti₂Ni (\(Fd\bar {3}m\)), and Ta₃Al (\({{P{{4}_{2}}} \mathord{\left/ {\vphantom {{P{{4}_{2}}} {mnm}}} \right. \kern-0em} {mnm}}\)). They are identified as reflections of three compounds, Ta_6.5Ni_6.5, Ti₂Ni, and Ta_2.84Al_0.91, with unit-cell parameters differing from these for the same compounds with the conservation of the structural type. An increase in the unit-cell parameters of all revealed phases is noted when compared with known binary intermetallic compounds. This can be associated with the presence of Al atoms in the crystal lattice from the Ta_6.5Ni_6.5 phase and Al and Ta atoms in the phase with the Ti₂Ni structural type. Phases Ta_6.5Ni_6.5 and Ti₂Ni phases are identified as Ta₆Ni₆Al and Ta₂Ni_0.5Al_0.5 by X-ray structural analysis and crystal-chemical modeling, and their structural type, composition, and unit-cell parameters are determined. The structure and composition are refined by the full-profile analysis, and the unit-cell parameters of the phases and their quantitative ratio in the material are determined. The phase composition of the material is as follows, wt %: 47 Ta₆Ni₆Al, 16 Ta₂Ni_0.5Al_0.5, and 37 Ta₃Al.

中文翻译：

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Ta-Ni-Al体系三元相的组成和晶体结构

摘要

研究了由5Ta-2Ni-3Al（at％）粉末混合物自蔓延高温合成（SHS）并随后在3000°C真空重熔所产生的化合物的组成和晶体结构。的SHS产品包含以下阶段：TaNiAl（莱夫斯τ _1个相），镍铝，镍₂铝₃，和Ta。其微观结构包括Ta ₈₅ Ni ₇ Al ₈，Ta ₅₂ Ni ₂₀ Al ₂₈和Ta ₅₃ Ni ₂₅ Al ₂₂根据元素分析数据确定三元相。重熔材料的X射线衍射图显示了所考虑的Ta-Ni-Al系统中未知三元相的反射。基于同质性方法，发现这些反射属于三个相，其结构类型为W ₆ Fe ₇（\（R \ bar {3} m \）），Ti ₂ Ni（\（Fd \ bar {3} m \））和Ta ₃ Al（\（{{P {{4} _ {2}}} \ mathord {\ left / {\ vphantom {{P {{4} _ {2}}} {mnm} }} \ right。\ kern-0em} {mnm}} \））。它们被确定为三种化合物Ta _6.5 Ni _6.5，Ti ₂ Ni和Ta的反射_2.84 Al _0.91，与具有相同结构类型的相同化合物的晶胞参数不同。与已知的二元金属间化合物相比，所有显露相的晶胞参数都有所增加。这可能与来自Ta _6.5 Ni _6.5相的晶格中存在Al原子以及具有Ti ₂ Ni结构类型的相中的Al和Ta原子有关。Ta _6.5 Ni _6.5和Ti ₂ Ni相被确定为Ta ₆ Ni ₆ Al和Ta ₂ Ni _0.5 Al _0.5通过X射线结构分析和晶体化学建模，确定了它们的结构类型，组成和晶胞参数。通过全轮廓分析精炼结构和组成，并确定相的晶胞参数及其在材料中的定量比。材料的相组成如下，wt％：47 Ta ₆ Ni ₆ Al，16 Ta ₂ Ni _0.5 Al _0.5和37 Ta ₃ Al。