Video microscopy of granular deformation and strain localisation in partially-solid alloys

部分固态合金中晶粒变形和应变局部化的视频显微镜

• 批准号: EP/H016848/1
• 负责人: Christopher Gourlay
• 金额: $ 12.94万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH016848%2F1
• 关键词: Video; microscopy; granular; deformation; strain

This project seeks to use video microscopy to observe and measure, for the first time, the deformation mechanisms in partially-solid alloys. The focus is on one of the least studied areas of mushy-zone mechanics, rheology at 'intermediate' solid fraction, when multiple equiaxed crystals are in contact but have negligible cohesion. These microstructures are commonly deformed during industrial casting processes, for example the high-pressure die-casting of Al- and Mg-alloy automotive chassis components. It has been found that, when severe deformation occurs at the same time as solidification, the as-cast microstructure and defects are markedly different to those in most textbooks. Recent research has suggested that this is because deformation during solidification causes the alloy to deform as a granular material.Granular materials are simply the disordered assemblies of particles we encounter every day from the soil in the garden to salt on the kitchen table. However, the mechanics of granular materials can be complex, emerging from the mechanical interactions between discrete particles which are often unrelated to the mechanics of the particles themselves. For example, grains of wheat in a silo have markedly different mechanical properties to the grains of sand in a soil, yet the deformation behaviour of large piles of each share many mechanical similarities. Granular materials are important across the physical sciences and engineering and the application of granular mechanics is central to research on (i) soil mechanics in Civil Engineering, (ii) plate tectonics and earthquakes in Earth Science, (iii) the flow and storage of cereal crops in Agriculture, and (iv) the handling of pharmaceutical powders and pastes in Chemical Engineering. This Project seeks to provide direct experimental proof that partially-solid alloys should also be considered a form of granular material. The ultimate aim is for the phenomena and mechanisms revealed by video-microscopy to form the foundation for future granular theories of partially-solid alloy deformation.To enable these scientific advances, an innovative apparatus for the direct in-situ measurement of deformation in the mushy-zone will be developed. The approach is to simultaneously measure (i) phenomena at the scale of the crystals in-situ and (ii) global mechanical data. The knowledge of granular deformation from the parallel disciplines of Soil Mechanics and Earth Science will be used in developing the apparatus and in interpreting the results. The research will generate knowledge of the deformation mechanisms operating at the scale of the crystals, and quantitatively link the micromechanisms with the global rheology. Research will also study how granular shear bands form and grow in partially-solid alloys.

该项目旨在首次使用视频显微镜观察和测量部分固态合金的变形机制。重点是糊状区域力学研究最少的领域之一，即“中间”固体分数的流变学，此时多个等轴晶体接触但内聚力可以忽略不计。这些微观结构通常在工业铸造过程中变形，例如铝合金和镁合金汽车底盘部件的高压压铸。研究发现，当凝固同时发生严重变形时，铸态组织和缺陷与大多数教科书上的显着不同。最近的研究表明，这是因为凝固过程中的变形导致合金变形为粒状材料。粒状材料只是我们每天遇到的颗粒的无序集合体，从花园里的土壤到厨房桌子上的盐。然而，颗粒材料的力学可能很复杂，是由离散颗粒之间的机械相互作用产生的，而这些机械相互作用通常与颗粒本身的力学无关。例如，筒仓中的小麦粒与土壤中的沙粒具有明显不同的机械特性，但大堆的变形行为却有许多机械相似之处。颗粒材料在物理科学和工程中非常重要，颗粒力学的应用是以下研究的核心：(i) 土木工程中的土壤力学、(ii) 地球科学中的板块构造和地震、(iii) 农业中谷类作物的流动和储存，以及 (iv) 化学工程中药物粉末和糊剂的处理。该项目旨在提供直接的实验证明，证明部分固态合金也应被视为颗粒材料的一种形式。最终目标是通过视频显微镜揭示的现象和机制为未来部分固态合金变形的颗粒理论奠定基础。为了实现这些科学进步，将开发一种用于直接原位测量糊状区域变形的创新装置。该方法是同时测量（i）晶体原位尺度的现象和（ii）全局力学数据。来自土壤力学和地球科学平行学科的颗粒变形知识将用于开发设备和解释结果。该研究将产生在晶体尺度上运行的变形机制的知识，并将微观机制与整体流变学定量联系起来。研究还将研究粒状剪切带如何在部分固态合金中形成和生长。

项目成果

Synchrotron Radiography Studies of Shear-Induced Dilation in Semisolid Al Alloys and Steels

半固态铝合金和钢剪切诱发膨胀的同步辐射照相研究

• DOI: 10.1007/s11837-014-1029-5
• 发表时间: 2014
• 期刊: JOM
• 影响因子: 2.6
• 作者: Gourlay C

In situ study of granular micromechanics in semi-solid carbon steels

• DOI: 10.1016/j.actamat.2013.03.043
• 发表时间: 2013-06-01
• 期刊: ACTA MATERIALIA
• 影响因子: 9.4
• 作者: Fonseca, J.;O'Sullivan, C.;Gourlay, C. M.
• 通讯作者: Gourlay, C. M.

Characterization of Shear Deformation Based on In-situ Observation of Deformation in Semi-Solid Al-Cu Alloys and Water-Particle Mixture ??????Al-Cu????-??????????????????????????????????

基于半固态铝铜合金和水颗粒混合物变形的原位观察的剪切变形表征 ??????Al-Cu??????-????????????

• DOI: 10.2355/tetsutohagane.99.141
• 发表时间: 2013
• 期刊: Tetsu-to-Hagane
• 作者: Nagira T

Exploring dendrite coherency with the discrete element method

用离散元方法探索枝晶相干性

• DOI: 10.1016/j.actamat.2011.11.042
• 发表时间: 2012
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: Yuan L