Experimental and Theoretical Investigations of Gum Metal

胶质金属的实验和理论研究

• 批准号: 1105081
• 负责人: Daryl Chrzan
• 金额: $ 42万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1105081&HistoricalAwards=false
• 关键词: Experimental; Theoretical; Investigations; Gum; Metal

TECHNICAL SUMMARY: Gum metals are Ti-Nb based alloys that display remarkable mechanical properties, including super-elasticity, super-strength, large ductility, zero coefficient of thermal expansion and elastic constants that remain constant over a range of temperatures. Surprisingly, plasticity in these materials appears to be mediated neither by dislocation motion nor by phase transformation. Instead, these materials appear to deform at their ideal strength. If so, these alloys represent a new type of structural alloy. Their unusual mechanical behavior is linked to a strong elastic anisotropy that develops as the composition of the alloy is driven towards a phase transformation. This anisotropy allows for easy dislocation pinning, the extreme spreading of the dislocation cores, and plays a role in the suppression of phase transformations that might otherwise weaken the alloys. The project involves two primary goals. First it aims to understand experimentally the precise mechanism governing plasticity in these unusual alloys. This understanding will be developed using a combination of nanoindentation and transmission electron microscopy experiments. Second, the project will develop theoretical tools and ideas capable of explaining the observed deformation behavior. Initial theoretical studies will focus on the structure of dislocations within Gum Metals paying particular attention to the implications of spread dislocation cores and dislocation core overlap. The understanding so obtained will be used to identify new alloys systems with the potential to deform similarly to Gum Metals.NON-TECHNICAL SUMMARY: The ideal strength of a material is the largest possible load the material can withstand before becoming permanently deformed. Typically, the observed strength of a material is 1/100th or less of its ideal strength, largely because defects known as dislocations are able to move throughout the crystal at stresses well below the ideal strength. This understanding lies at the heart of modern metallurgy, and guides the development of most structural alloys. Gum Metal is a recently discovered Ti-Nb based alloy with a long list of remarkable mechanical properties. The most striking characteristic is that Gum Metal appears to deform at ideal strength via a unique dislocation-free deformation mechanism. The goal of this research is to identify and understand the deformation mechanism(s) that gives rise to the remarkable properties of Gum Metal, and to use this understanding to develop the metallurgical principles that govern Gum Metal behavior. These principles will then be used to search for new materials that display mechanical properties similar to Gum Metal. The identification of novel metallurgical principles has the potential to enable the development of a new class of structural materials. Such materials would impact a broad range of technologies including transportation and energy generation. Students working towards their doctoral degrees will conduct much of the research. Course materials geared toward introducing high school physics students to the discipline of materials science and engineering will be developed and exemplified by the role of structural materials in the sport of skateboarding---a sport popular with teenagers.

技术摘要：口香糖是基于Ti-Nb的合金，它们显示出显着的机械性能，包括超弹性，超强度，大延性，热膨胀的零系数和在温度范围内保持恒定的弹性常数。 出乎意料的是，这些材料中的可塑性似乎既不是通过脱位运动也不是通过相变介导的。 相反，这些材料似乎以其理想的强度变形。 如果是这样，这些合金代表了一种新型的结构合金。它们的异常机械行为与强大的弹性各向异性有关，该弹性各向异性随着合金的组成而发展为相变。 这种各向异性允许易于脱位，脱位核心的极端扩散，并在抑制可能削弱合金的相变的抑制中起作用。该项目涉及两个主要目标。 首先，它旨在通过实验了解这些异常合金中可塑性的确切机制。 这种理解将使用纳米识别和透射电子显微镜实验的组合来开发。 其次，该项目将开发能够解释观察到的变形行为的理论工具和思想。 最初的理论研究将集中于牙龈金属内错位的结构，特别关注扩散位错核心和错位核心核心重叠的含义。如此获得的理解将用于识别具有类似于牙龈金属的可能变形的新合金系统。Non-non-technical摘要：材料的理想强度是材料在永久变形之前所承受的最大载荷。通常，观察到的材料的强度为其理想强度的1/100或更小，主要是因为称为脱位的缺陷能够以远低于理想强度的压力在整个晶体中移动。 这种理解是现代冶金的核心，并指导大多数结构合金的发展。 牙龈金属是最近发现的基于Ti-NB的合金，具有长远的机械性能。最引人注目的特征是，牙龈金属似乎通过独特的无位错变形机制在理想强度下变形。 这项研究的目的是识别和理解引起牙龈金属的显着特性的变形机制，并利用这种理解来发展控制牙龈金属行为的冶金原理。 然后，这些原理将用于搜索显示类似于牙龈金属的机械性能的新材料。 新型冶金原理的识别有可能使新的结构材料的发展。这样的材料将影响广泛的技术，包括运输和能源产生。 致力于博士学位的学生将进行大部分研究。旨在将高中物理学生介绍给材料科学和工程学科的课程材料将由结构材料在滑板运动中的作用开发和举例说明 - 这是一项受青少年流行的运动。