Collaborative Research: In situ Diffraction and Cohesive-Zone Studies of the Fatigue-Crack-Growth Behavior in Mg Alloys

合作研究：镁合金疲劳裂纹扩展行为的原位衍射和内聚区研究

• 批准号: 1809696
• 负责人: Huck Beng Chew
• 金额: $ 22.5万
• 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: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809696&HistoricalAwards=false
• 关键词: Collaborative; Research; situ; Diffraction; Cohesive

Non-Technical Abstract: The accelerated adoption of magnesium alloys as structural components in the automobile and aerospace industry is driven by their unique properties of low density, high strength-to-weight ratio, and high specific stiffness. However, the fatigue properties of magnesium alloys and associated failure mechanisms have not been well-characterized, which severely limits the technological viability of these lightweight alloys. This award supports the fundamental research to provide the microstructural-level understanding of the failure processes, which ultimately govern the fatigue life of magnesium alloys. The research will pave the way towards the intelligent design of advanced, lightweight structural alloys with the improved fatigue life. In the broader sense, this research will impact the aerospace and automotive industries and would help U.S. improve its manufacturing competitiveness. The unique experimental and modeling tools will help enrich the current course curriculum on mechanics and materials at both the University of Tennessee and University of Illinois. A demonstrative toolkit will expose high school students at both universities to concepts of fracture and failure, and how crack stopping mechanisms can be introduced to improve fatigue life.Technical Abstract:The goal of this research is to couple fatigue-crack-growth studies of magnesium alloys, with in situ nondestructive measurements and micromechanical modeling investigations, which will establish the connection between microscopic failure processes and macroscopic fatigue-crack-growth properties. The primary objective is to identify the roles of the surrounding plasticity and crack-tip process zones in the resistance to fatigue-crack growth of magnesium alloys. Within the surrounding plastic zone, in situ neutron-diffraction measurements and high-energy synchrotron X-ray diffraction techniques will provide the unprecedented information on plastic anisotropy, twin polarity, flow non-normality, and texture evolution in magnesium alloys under the arbitrary stress multiaxiality. Within the process zone, which is inaccessible to experimental measurements, a novel nonlinear field projection scheme will be used to inversely reconstruct the cohesive zone laws for fatigue-crack growth uniquely from the surrounding deformation fields that are measured by the diffraction experiments. By linking top-down stress analyses with bottom-up failure mechanisms at inter- and intra-granular scales, this fundamental research can lead to predictive models based on microstructural understanding with which materials scientists can utilize to improve the fatigue life of advanced structural alloys.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.

非技术摘要：镁合金作为结构部件在汽车和航空航天工业中的加速采用是由其低密度、高强度重量比和高比刚度的独特性能推动的。然而，镁合金的疲劳性能和相关的失效机制还没有得到很好的表征，这严重限制了这些轻质合金的技术可行性。该奖项支持基础研究，以提供对失效过程的微观结构水平的了解，最终决定镁合金的疲劳寿命。这项研究将为提高疲劳寿命的先进、轻质结构合金的智能化设计铺平道路。从更广泛的意义上讲，这项研究将对航空航天和汽车行业产生影响，并将有助于美国提高其制造业竞争力。独特的实验和建模工具将有助于丰富田纳西大学和伊利诺伊大学目前的力学和材料课程。一个演示工具包将使两所大学的高中生了解断裂和失效的概念，以及如何引入裂纹阻止机制来提高疲劳寿命。技术摘要：本研究的目标是将镁合金的疲劳裂纹扩展研究与原位无损测量和细观力学模型研究相结合，从而建立微观破坏过程和宏观疲劳裂纹扩展特性之间的联系。主要目的是确定周围塑性和裂纹尖端过程区在镁合金抗疲劳裂纹扩展中的作用。在周围的塑性区，原位中子衍射仪和高能同步X射线衍射仪将提供镁合金在任意应力多轴度下的塑性各向异性、孪极性、流动非正态和织构演化等前所未有的信息。在实验测量无法到达的过程区内，将使用一种新的非线性场投影方案，从绕射实验测量的周围变形场中唯一地逆重建疲劳裂纹扩展的内聚区规律。通过将自上而下的应力分析与颗粒间和晶内尺度的自下而上的失效机制联系起来，这项基础性研究可以产生基于微观结构理解的预测模型，材料科学家可以利用这些模型来提高先进结构合金的疲劳寿命。该奖项反映了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。

项目成果

Microstructure effects on fatigue crack growth in additively manufactured Ti–6Al–4V

• DOI: 10.1016/j.msea.2020.139993
• 发表时间: 2020-09
• 期刊: Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
• 影响因子: 6.4
• 作者: R. VanSickle;David Foehring;H. Chew;J. Lambros

Two-scale porosity effects on cohesive crack growth in a ductile media

• DOI: 10.1016/j.ijsolstr.2020.04.035
• 发表时间: 2020-09-01
• 期刊: INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES
• 影响因子: 3.6
• 作者: Cui, Y.;Gao, Y. F.;Chew, H. B.
• 通讯作者: Chew, H. B.

In situ monitoring of dislocation, twinning, and detwinning modes in an extruded magnesium alloy under cyclic loading conditions

• DOI: 10.1016/j.msea.2021.140860
• 发表时间: 2021-02
• 期刊: Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
• 影响因子: 6.4
• 作者: D. Xie;Z. Lyu;Yuan Li;P. Liaw;H. Chew;Yang Ren;Yan Chen;K. An;Yanfei Gao

Micromechanical origin of the enhanced ductility in twinless duplex Mg–Li alloy

• DOI: 10.1016/j.msea.2021.141305
• 发表时间: 2021-04
• 期刊: Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
• 影响因子: 6.4
• 作者: D. Xie;Z. Lyu;M. Fan;H. Chew;P. Liaw;H. Bei;Zhongwu Zhang;Yanfei Gao