Materials World Network: Deformation via the Transformation of Hierarchical Microstructures

材料世界网络：通过分层微观结构的转变实现变形

• 批准号: 1008167
• 负责人: Peter Mullner
• 金额: $ 48万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1008167&HistoricalAwards=false
• 关键词: Materials; World; Network; Deformation; via

This Materials World Network research project between Prof. Peter Müllner, Prof. William Knowlton, and Res. Assist. Prof. Paul Lindquist at Boise State University (BSU) and Profs. Steffen Brinckmann and Alexander Hartmaier at the Ruhr University Bochum, Germany, focuses on the deformation mechanism of materials with hierarchically twinned microstructures. While such microstructures occur in many functional materials including shape-memory alloys and ferroelastic ceramics, the experimental part of this study concentrates on magnetic shape-memory alloys (MSMAs). The mechanical and magneto-mechanical properties of magnetic shape-memory alloys strongly depend on details of the twin microstructure, which can be varied via appropriate thermo-magneto-mechanical training treatments. For well-trained single crystals with a single operating twinning system, the twinning stress is very low (about 0.1 MPa), the magnetic-field-induced strain is large (6-10 %), and the fatigue life is short (about 10,000 cycles). For un-trained single crystals with self-accommodated, hierarchically twinned martensite, the twinning stress is relatively high (about 2 MPa), the magnetic-field-induced strain is small (about 0.1 %), and the fatigue life is long (exceeding 100 million cycles). The deformation mechanism of hierarchically twinned microstructures will be studied experimentally at Boise State University on all length scales with in-situ deformation experiments while numerical studies will be performed at the Ruhr University Bochum. The experiments include in-situ straining in the transmission electron microscope (microscale), in the scanning probe microscope (mesoscale), and with optical imaging in the tensile test bench (macroscale). The defect content of the twin microstructure will be obtained from the experimental study. Disclination dipoles, i.e. mesoscopic line defects with a shear displacement field, represent the displacement fields of twins on all hierarchical levels. A disclination dynamics code will be developed and applied to a large scale numerical study. By supplying the numerical study with experimental data, and by systematically varying experimental and numerical parameters, a quantitative fundamental understanding of the mechanical (and magneto-mechanical) properties of (magnetic) shape-memory alloys with complex hierarchical twin-microstructures will be generated. A strong impact on technology is anticipated: The quantitative understanding gained with this study will allow the development of fast and high-rescission MSMA actuators with large stroke and long lifetime for applications including valves for ink-jet printers and micropumps for biomedical systems. This project will produce the computational tools required for leading MSMAs from the research laboratory to industrial technologies.

这个材料世界网络的研究项目之间的教授彼得Müllner，教授威廉诺尔顿，和Res. Assist。博伊西州立大学（BSU）的保罗·林德奎斯特教授和德国波鸿鲁尔大学的Steffen Brinckmann和亚历山大Hartmaier专注于具有分层孪生微观结构的材料的变形机制。虽然这种微结构出现在许多功能材料中，包括形状记忆合金和铁弹性陶瓷，但本研究的实验部分集中在磁性形状记忆合金（MSMA）上。磁性形状记忆合金的机械和磁机械性能强烈地依赖于孪晶微结构的细节，其可以通过适当的热-磁-机械训练处理来改变。对于具有单一操作孪生系统的良好训练的单晶，孪生应力非常低（约0.1MPa），磁场诱导应变大（6- 10%），并且疲劳寿命短（约10，000次循环）。对于具有自适应、分级孪晶马氏体的未经训练的单晶，孪晶应力相对高（约2 MPa），磁场诱导应变小（约0.1%），并且疲劳寿命长（超过1亿次循环）。分级孪生微结构的变形机制将在博伊西州立大学进行实验研究，在所有长度尺度上进行原位变形实验，而数值研究将在鲁尔大学波鸿进行。实验包括在原位应变的透射电子显微镜（微观），在扫描探针显微镜（中尺度），并在拉伸试验台（宏观）的光学成像。通过实验研究，可以得到孪晶组织的缺陷含量。向错偶极子，即具有剪切位移场的介观线缺陷，代表所有层次上的孪晶的位移场。一个向错动力学代码将被开发并应用于大规模的数值研究。通过提供实验数据的数值研究，并通过系统地改变实验和数值参数，（磁性）形状记忆合金的机械（和磁机械）性能的定量基本理解与复杂的层次孪生微结构将产生。预计对技术的强烈影响：这项研究获得的定量理解将允许开发快速和高分辨率的MSMA致动器，具有大冲程和长寿命，适用于包括喷墨打印机阀门和生物医学系统微型泵在内的应用。该项目将产生从研究实验室到工业技术的领先MSMA所需的计算工具。