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首页> 外文学位 >The influence of microstructure on the deformation behavior of beta solution heat treated and aged titanium aluminum tin zirconium molybdenum chromium silicate.
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The influence of microstructure on the deformation behavior of beta solution heat treated and aged titanium aluminum tin zirconium molybdenum chromium silicate.

机译：显微组织对热处理和时效的钛铝锡锆钼铬铬热处理后的β溶液变形行为的影响。

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摘要

Composite alpha/beta stereographic projections and slip system misorientation diagrams were developed and used to establish a new understanding regarding anisotropic deformation behavior of alpha and beta phases aligned according to the Burgers orientation relationship. Application of these tools showed that a 2-fold, maximum common crystal symmetry existed between single variants of Burgers oriented alpha and beta phases, which placed specific requirements on alignment and response of mating slip systems in alpha and beta phases. Of particular import were implications for crystallographic elements of mating slip systems that were found to be oriented within 180° of each other, i.e. anisotropic deformation behavior was predicted according to requirements of 2-fold maximum common crystal symmetry. Inspection of misorientation between mating slip systems established new requirements for determining the breadth of anisotropic slip behavior for a-basal, a-prism, a-pyramidal and c+a pyramidal slip systems. It was shown testing at 3, 6, 6, and 12 maximum Schmid factor loading axes was required to fully measure anisotropic deformation behavior in these slip systems, respectively. This meant each mated slip system would have 1, 2, 2 and 4 unique responses when loaded at orientations of maximum Schmid factor on the alpha slip system. The root cause of these anisotropic responses was shown to result from large changes in Schmid factor on beta slip systems when loading conditions on alpha slip systems were held constant, i.e. at maximum Schmid factor. Changes in Schmid factor on mating beta slip systems were shown to be a natural consequence of differences in crystal symmetry between alpha and beta phases oriented according to the Burgers orientation relationship.;Extension of this information to titanium microstructures consisting of multiple alpha variants in a single beta grain showed that 144 possible combinations of two adjacent alpha variants could be grouped according to six characteristic crystallographic and morphological misorientations. Growth directions between pairs of alpha/beta variants were shown to have interface misorientations of (0°/180°), (24.9°/155.1°), (54.5°/125.5°), (60.76°/119.3°), (77.9°/102.1°) and (80.6°/99.4°). This information, combined with that in slip system misorientation diagrams, was used to make qualitative predictions of relative ease and difficulty of slip transmission between combinations of alpha/beta/alpha variants based on in-plane and out-of-plane misorientations of slip planes and slip directions. For example, slip transmission between variants of near parallel alignment (Delta = 1.38°) between (0001) and {10-11} with a common {011}111> slip system was predicted, then confirmed through Transmission Electron Microscopy (TEM) imaging techniques.;Six variations of the production "Triplex" Ti-62222S heat treatment process were developed and applied to effect large changes in room temperature tensile deformation behavior. Large changes in morphology of primary alpha features and the presence of alpha2-Ti3Al in the alpha promoted large reductions in fracture stress and fracture strain capability of beta solution heat-treated and aged Ti-62222S. These effects were shown to be additive, so that the combination of high amounts of aligned colony alpha + high presence of alpha2-Ti3Al in the alpha produced the lowest fracture stress and fracture strain. Work hardening in all six microstructures was relatively low, e.g. n ranging between ∼0.05 and 0.1. As with fracture behavior, increasing the amount of aligned or colony microstructure and/or increasing the presence of alpha2-Ti 3Al in the alpha were shown to lower work hardening. Examination of fracture surfaces and polished cross sections perpendicular to fracture surfaces revealed an associated transition from transgranular to intergranular fracture with increasing amount of aligned or colony alpha and if the final aging treatment increased the presence of alpha2-Ti3Al in the alpha. An important factor distinguishing the two fracture modes was the presence of fine voids at alpha/beta interfaces in sub-fracture surface regions just below the main crack.;More detailed inspection of deformed materials using OIM and TEM imaging techniques showed several interesting and previously unreported behaviors for Ti-62222S. These included the presence of deformation twins in the alpha, emission of dislocations from alpha/beta interfaces, very strong fringe contrast between pairs of dislocations gliding on all slip systems and dislocations in the beta with b = [010] in pile-ups associated with dislocations gliding on an unaligned a2-basal slip system. Information gleaned from composite alpha/beta stereographic projections and slip system misorientation diagrams proved critical in developing proper interpretations of these observations. (Abstract shortened by UMI.)
机译：开发了复合的alpha / beta立体投影和滑移系统取向错误图，并用于建立有关根据Burgers取向关系对齐的alpha和beta相的各向异性变形行为的新认识。这些工具的应用表明，在Burgers定向的α和β相的单个变体之间存在2倍最大的晶体对称性，这对交配滑模系统在α和β相中的排列和响应提出了特殊要求。特别重要的是对交配滑移系统的晶体学元素的暗示，发现它们相互之间的取向为180°，即根据2倍最大常见晶体对称性的要求预测了各向异性变形行为。对交接滑移系统之间未对准的检查，为确定a基，a棱镜，a金字塔形和c + a金字塔滑移系统的各向异性滑移行为的宽度提出了新要求。结果表明，分别需要在3、6、6和12个最大Schmid因子加载轴上进行测试，才能分别测量这些滑移系统中的各向异性变形行为。这意味着，当在alpha滑移系统上以最大Schmid因子的方向加载时，每个配对滑移系统将具有1、2、2和4个唯一的响应。这些各向异性响应的根本原因表明是当α滑移系统的载荷条件保持恒定（即最大Schmid系数）时，β滑移系统的Schmid因子发生了较大变化。交配的β滑移系统上Schmid因子的变化被证明是根据Burgers取向关系定向的α相和β相之间晶体对称性差异的自然结果。该信息扩展到由多个α变体组成的钛微结构β晶粒表明，可以根据六个特征性的晶体学和形态学取向将144个两个相邻的alpha变体的可能组合进行分组。成对的alpha / beta变体之间的生长方向显示为（0°/ 180°），（24.9°/ 155.1°），（54.5°/ 125.5°），（60.76°/ 119.3°），（77.9） °/ 102.1°）和（80.6°/ 99.4°）。该信息与滑移系统方向错误图中的信息相结合，用于基于滑移面的平面内和平面外方向错误做出关于α/β/ alpha变体组合之间滑移传递的相对容易程度和难度的定性预测和滑动方向。例如，预测了在（0001）和{10-11}之间使用通用的{011} <111>滑移系统在接近平行对齐（Delta = 1.38°）的变体之间发生滑移传输，然后通过透射电子显微镜（TEM）进行了确认开发了六种生产“ Triplex” Ti-62222S热处理工艺的变体，并将其应用于室温拉伸变形行为的大变化。主要的阿尔法特征形态上的大变化以及阿尔法中存在的α2-Ti3Al促进了热处理和老化的Ti-62222S的β溶液的断裂应力和断裂应变能力的大幅降低。这些作用被证明是累加的，因此大量对齐的菌落α+α中大量存在的α2-Ti3Al的组合产生了最低的断裂应力和断裂应变。所有六个微结构的加工硬化都相对较低，例如n在〜0.05和0.1之间。与断裂行为一样，增加排列或集落微结构的数量和/或增加α中α2-Ti3Al的存在可降低加工硬化。断裂表面和垂直于断裂表面的抛光横截面的检查显示，随着排列的或集落的α的数量增加，如果从最终的老化处理增加了α2 -Ti 3 Al的存在，则伴随着从跨晶向过渡到晶间断裂的过渡。区分这两种断裂模式的重要因素是在主裂纹正下方的子断裂表面区域的alpha / beta界面处存在细小的空隙。使用OIM和TEM成像技术对变形材料进行的更详细检查显示了一些有趣的且以前没有报道Ti-62222S的行为。这些包括阿尔法变形双胞胎的存在，阿尔法/贝塔界面的位错发射，在所有滑移系统上滑动的成对的位错之间的非常强烈的条纹对比以及在b = [010]的堆积物中的位错与脱位在未对齐的a2基滑移系统上滑动。事实证明，从合成的alpha / beta立体投影和滑移系统方向错误图中收集的信息对于开发对这些观测值的正确解释至关重要。 （摘要由UMI缩短。）

著录项

  • 作者

    Broderick, Thomas Froats.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 238 p.
  • 总页数 238
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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