Collaborative Research: Closing the Bulk Metallic Glass Data Gap in the Supercooled Region

合作研究：缩小过冷区域的块状金属玻璃数据差距

• 批准号: 1710744
• 负责人: William Johnson
• 金额: $ 17.61万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1710744&HistoricalAwards=false
• 关键词: Collaborative; Research; Closing; Bulk; Metallic

NON-TECHNICAL DESCRIPTION:Metallic glasses are high-strength metallic alloys that have a random, non-crystalline structure. Like all glasses, they behave like a frozen liquid with flow characteristics determined by its viscosity, or resistance to flow, which varies with temperature. Understanding how flow varies with temperature is a key component both to unlocking the physics behind the underlying structure of metallic glasses, and knowing how its properties influence, and are influenced by, processing. There are three different behaviors: At low temperature the glass behaves as a solid; at moderate temperature, in which the glass flows like a thick liquid, and at high temperature the glass is fully melted. Viscosity measurement of the low- and high-temperature regimes is readily accessible through existing methods, but to date no methods are available to measure viscosity in the thick liquid regime. The focus of this research is to employ newly developed methods to measure viscosity of the thick liquid by rapidly heating the glass while measuring their elastic response. The data collected will be used to identify the fundamental parameters that control flow, develop and refine appropriate models for describing flow behavior, and improve processing techniques need for creating viable commercial products. This collaborative effort will be supported by faculty and graduate students at California State University, Northridge, and California Institute of Technology. Graduate students will mentor underrepresented summer high school and college interns, expanding their representation in the professional community and exciting them to pursue STEM careers.TECHNICAL DESCRIPTION:This proposal describes interdisciplinary and collaborative research addressing a conspicuous data gap in the rheological properties of bulk metallic glass alloys (BMGs). BMGs, with their outstanding hardness, toughness, strength and processability, show promise to combine the strengths of metals with the ease of plastic processing, and the potential for energy efficient, environmentally clean manufacturing. The gap in the rheological data exists in the supercooled liquid (SCL) region, between the glass transition and the crystallization temperatures. This data is pivotal in advancing the theory of glassy liquids, and directly impacts processability. We propose to measure the viscosity, and other thermodynamic properties, of a series of metallic glass compositions in this range using rapid temperature excursions driven by ohmic heating (rapid discharge forming, RDF). High-speed time-dependent deformation measurements of a sample under load will be used to determine viscosity variation with temperature. In separate experiments, the ultrasonic pulse-echo technique, coupled with high-speed infrared pyrometry, will be used to measure the elastic shear wave velocity variation with temperature. Data will be incorporated in existing glass rheology models, and new models will be developed as required. Application of the knowledge gained through these studies will be applied to the proof-of-concept processing of metallic glasses, making net-shape objects through thermoplastic forming, and further understanding of the microstructure/processing/properties relationship in glasses and glassy metals.

非技术描述：金属玻璃是具有随机非晶体结构的高强度金属合金。像所有的玻璃一样，它们的行为就像一种冻结的液体，其流动特性取决于其粘度或流动阻力，而粘度或流动阻力随温度而变化。了解流动如何随温度变化是解开金属玻璃底层结构背后的物理学，以及了解其性质如何影响加工的关键组成部分。有三种不同的行为：在低温下，玻璃表现为固体;在中等温度下，玻璃像粘稠的液体一样流动，在高温下，玻璃完全熔化。通过现有方法可以容易地获得低温和高温状态的粘度测量，但是迄今为止还没有方法可用于测量粘稠液体状态中的粘度。本研究的重点是采用新开发的方法，通过快速加热玻璃，同时测量其弹性响应来测量粘稠液体的粘度。收集的数据将用于确定控制流动的基本参数，开发和完善描述流动行为的适当模型，并改进创造可行的商业产品所需的加工技术。这项合作努力将得到加州州立大学北岭分校和加州理工学院教师和研究生的支持。研究生将指导未被充分代表的暑期高中和大学实习生，扩大他们在专业社区的代表性，并激发他们追求STEM职业生涯。技术描述：该提案描述了跨学科和合作研究，解决了块体金属玻璃合金（BMG）流变性能的明显数据缺口。BMG具有出色的硬度、韧性、强度和可加工性，有望将金属的强度与塑料加工的便利性结合起来，并具有节能、环保的制造潜力。流变数据中的差距存在于过冷液体（SCL）区域，在玻璃化转变和结晶温度之间。这些数据在推进玻璃态液体理论方面至关重要，并直接影响加工性能。我们建议测量粘度，和其他热力学性质，在此范围内的一系列金属玻璃组合物使用快速的温度漂移驱动的欧姆加热（快速放电形成，RDF）。在负载下的样品的高速时间依赖性变形测量将用于确定粘度随温度的变化。在单独的实验中，超声脉冲回波技术，结合高速红外测温，将被用来测量弹性剪切波速度随温度的变化。数据将被纳入现有的玻璃流变模型，并将根据需要开发新的模型。通过这些研究获得的知识的应用将被应用于金属玻璃的概念验证加工，通过热塑性成形制造净形物体，并进一步了解玻璃和玻璃金属的微观结构/加工/性能关系。

项目成果

First-Order Phase Transition in Liquid Ag to the Heterogenous G-Phase

液态 Ag 到异质 G 相的一级相变

• 发表时间: 2020
• 期刊: The journal of physical chemistry letters
• 作者: Qi, An;Johnson, William L.;Samwar, Konrad;Corona, Sydney L.;Goddard III, William A.
• 通讯作者: Goddard III, William A.

Observation of an apparent first-order glass transition in ultrafragile Pt–Cu–P bulk metallic glasses

• DOI: 10.1073/pnas.1916371117
• 发表时间: 2020-01
• 期刊: Proceedings of the National Academy of Sciences
• 作者: J. Na;Sydney L. Corona;A. Hoff;W. Johnson

The first order L-G phase transition in liquid Ag and Ag-Cu alloys is driven by deviatoric strain

• DOI: 10.1016/j.scriptamat.2020.113695
• 发表时间: 2021-03
• 期刊: Scripta Materialia
• 影响因子: 6
• 作者: Q. An;W. Johnson;K. Samwer;Sydney L. Corona;W. Goddard

Formation of two glass phases in binary Cu-Ag liquid

• DOI: 10.1016/j.actamat.2020.05.060
• 发表时间: 2020-08-15
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: An, Qi;Johnson, William L.;Goddard, William A., III
• 通讯作者: Goddard, William A., III