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Characterization of nanocrystalline monolithic copper, titanium, titanium diboride and composite copper/titanium diboride particles and consolidates

机译：纳米晶体单片铜，钛，二硼化钛和复合铜/钛二硼化物颗粒的表征和固结

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摘要

Nanocrystalline materials have received considerable attention due to their novel properties. Their refined microstructures lead to high strengths and toughnesses relative to their coarse-grained counterparts. Properly designed nanostructured metal-matrix composites should maintain high strengths at elevated temperatures. Nanocrystalline powders of titanium diboride, titanium, copper and composite copper-coated titanium diboride were produced with two methods in the present research: low temperature solution phase synthesis and high temperature gas phase combustion synthesis. Powders from the two methods were fully characterized, primarily with electron microscopy, electron diffraction and X-ray diffraction to determine size, morphology, crystal structure and phase purity. Nanostructured powders varying in size from 1 nm to greater than 100 nm, have been produced by both methods. Due to extremely fine size of the powders, they have been observed to be unstable in air and subject to oxidation and other transformations. Convergent beam single crystal electron diffraction studies have characterized the crystal structure of the particles as it relates to external particle morphology. The effects of extremely large surface to volume ratios were observed as morphology variations in powders as were the effects of the two synthesis methods on the evolution of particle morphology. Powders have been consolidated by vacuum hot pressing and hot isostatic pressing, to produce compacts. Consolidates were observed to retain refined microstructures at high densities but were subject to impurities. Composite compacts with high volume fractions of nano-reinforcements were attained which would not be feasible with conventional processing methods. Deformation studies via electron microscopy and mechanical testing were performed on Cu compacts and revealed very high strengths and high recrystallization temperatures which were attributed to incorporated boron. Characterization provided feedback throughout the production process to develop production methods and improve the powders and bulk materials.
机译：纳米晶体材料由于其新颖的特性而受到了相当大的关注。相对于其粗粒度的同类产品，其精细的微结构可带来较高的强度和韧性。正确设计的纳米结构金属基复合材料应在高温下保持高强度。本研究采用两种方法制备了二硼化钛，钛，铜和复合铜包覆的二硼化钛纳米晶粉：低温固溶相合成和高温气相燃烧合成。通过电子显微镜，电子衍射和X射线衍射对这两种方法制得的粉末进行了全面表征，以确定尺寸，形态，晶体结构和相纯度。两种方法均生产了尺寸从1 nm到大于100 nm的纳米结构粉末。由于粉末的尺寸非常细，已观察到它们在空气中不稳定，并容易发生氧化和其他转化。会聚束单晶电子衍射研究已经表征了颗粒的晶体结构，因为它与外部颗粒形态有关。观察到非常大的表面体积比的影响作为粉末的形态变化，以及两种合成方法对颗粒形态演变的影响。粉末已通过真空热压和热等静压进行固结，以生产压粉。观察到固结物在高密度下保留了精细的微结构，但容易产生杂质。获得了具有高体积分数的纳米增强材料的复合压块，这对于常规加工方法是不可行的。通过电子显微镜和机械测试进行的变形研究是在Cu压块上进行的，显示出很高的强度和很高的重结晶温度，这归因于硼的结合。表征为整个生产过程提供了反馈，以开发生产方法并改善粉末和散装物料。

著录项

  • 作者

    Frey, Claire A.;

  • 作者单位

    Washington University in St. Louis.;

  • 授予单位 Washington University in St. Louis.;
  • 学科 Materials science.;Engineering Materials science.
  • 学位 D.Sc.
  • 年度 1995
  • 页码 192 p.
  • 总页数 192
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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