Elastic loading of metallic glass as a method to obtain defined enthalpy states

金属玻璃的弹性载荷作为获得定义的焓态的方法

• 批准号: 2003955
• 负责人: Robert Maass
• 金额: $ 42.97万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003955&HistoricalAwards=false
• 关键词: Elastic; loading; metallic; glass; method

NON-TECHNICAL SUMMARYThis project is dedicated to a novel class of metallic materials that are called metallic glasses (MGs). Opposite to normal metallic alloys, MGs have a disordered atomic structure, which makes them more like a frozen liquid than a crystal. This change in structure brings a long a series of advantages over conventional engineering metals, such as steels. However, one problem with MGs is that their processing is very difficult. The sensitivity of the glassy structure to various processing parameters leads to a large variety of structures and therefore properties. This limits the widespread use of MGs in applications and thus the exploitation of their exceptional properties. In order to overcome this problem, the PI uses a novel route of elastic loading protocols that aim at introducing a defined and quantifiable structural state, irrespective of casting history. The goal is to achieve a structural reference state that subsequently can be relaxed via thermal processing to any desired state and its corresponding property. If successful, this project therefore provides a reversible thermo-mechanical processing method that puts an end to the ill-defined structural states and property variations originating from MG casting. Such an advance will significantly promote the usage of these novel alloys in engineering applications, enabling, for example, more energy efficient devices, novel consumer goods, high-performant medical devices, or magnetic components. TECHNICAL SUMMARYDefined thermo-mechanical protocols are a key to target specific microstructures and therefore properties. Such knowledge is used in daily industrial operations to obtain a desired mechanical performance of crystalline metallic materials. Modifying the structure, and therefore mechanical properties of disordered metallic materials, also known as metallic glasses (MGs), is much less straightforward due to the lack of well-defined structure-property relationships. Furthermore, the lack of apparent length scales in the amorphous MG makes it very difficult to identify a given structural state. Therefore, one normally uses the measure of stored excess enthalpy to characterize the structural state. In this research project, the PI addresses this shortcoming by i) homogeneous rejuvenation via stresses within the elastic regime, and ii) by demonstrating how spatial correlation lengths of property fluctuations at different length scales directly quantify a given excess enthalpy state. This is achieved by using site-specific characterization methods at the micron- and nanoscale. The experiments will reveal saturation limits of rejuvenation, from which the PI constructs a thermo-mechanical deformation map on how to prepare well-defined and quantifiable structural states. If successful, this research project introduces a novel structure-property relationship for tailoring properties of MGs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术总结这个项目致力于一种新型的金属材料，称为金属玻璃(MGs)。与普通金属合金相反，MG具有无序的原子结构，这使得它们更像是冻结的液体，而不是晶体。这种结构上的变化带来了比传统工程金属(如钢)更多的一系列优势。然而，MG的一个问题是它们的处理非常困难。玻璃结构对各种工艺参数的敏感性导致了各种结构，从而导致了性能的变化。这限制了MG在应用中的广泛使用，从而限制了对其特殊特性的开发。为了克服这个问题，PI使用了一种新的弹性加载方案，其目的是引入一种定义的和可量化的结构状态，而不考虑铸造历史。其目的是获得结构基准状态，该结构基准状态随后可以通过热处理松弛到任何期望的状态及其相应的性质。如果成功，该项目因此提供了一种可逆热机械加工方法，结束了源自MG铸造的不明确的组织状态和性能变化。这一进展将极大地促进这些新型合金在工程应用中的使用，例如，能够制造更节能的设备、新型消费品、高性能医疗设备或磁性部件。技术总结明确的热力方案是确定特定微观结构和性能的关键。这些知识被用于日常工业操作，以获得所需的结晶金属材料的机械性能。由于缺乏明确的结构-性质关系，改变无序金属材料(也称为金属玻璃(MGs))的结构和机械性能就不那么简单了。此外，在非晶态MG中缺乏表观长度尺度，这使得识别给定的结构状态非常困难。因此，人们通常使用储存的超额热焓来表征结构状态。在这项研究项目中，PI通过i)通过弹性区域内的应力实现均匀的返老还童，以及ii)通过演示不同长度尺度下的属性涨落的空间相关长度如何直接量化给定的超额热态来解决这一缺点。这是通过使用微米和纳米尺度的特定部位的表征方法来实现的。这些实验将揭示回春的饱和极限，PI根据该极限构建关于如何准备定义明确且可量化的结构状态的热机械变形图。如果成功，这项研究项目将引入一种新颖的结构-财产关系来定制MG的财产。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。