SRAS++ single crystal elasticity matrix measurement in polycrystalline materials

许多材料是多晶体的，也就是说，它们是由许多不规则形状的单个晶体在内部一起生长而成的。这类多晶材料包括几乎所有的金属，因此与先进工程高度相关。单个晶体的弹性(三维刚性)需要用一个六乘六的弹性矩阵来描述，而不是一个单一的数字。虽然CIJ有36名成员，但最多只有21名成员是独立的，在大多数材料中，只有大约1/2打成员是独立的或非零的。材料的弹性CIJ不仅对了解材料的机械性能，而且对了解其他行为都是非常重要的，因为它直接受到晶体中原子排列的影响。令人惊讶的是，在多晶材料中没有简单的方法来测量CIJ。在这项提议中开发的技术SRAS++发明之前，唯一可行的方法是制备材料的单晶，然后使用该单晶测量CIJ。然而，制备其中许多材料的单晶是极其困难、缓慢和昂贵的。此外，如果晶体是专门生长的，它并不能真正代表真正的块状多晶材料，因为制备条件将与块状晶体非常不同。然而，如果晶体从大块中分离出来(一项非常困难的任务)，这就会损坏原始标本，使其不适合用于有价值的材料或作为评估真实产品的方法。在这个建议中，我们将开发一种新发明的技术，SRAS++。这是基于一种激光超声成像技术，SRAS，它使用表面声波来询问材料中的晶体(颗粒)。在SRAS++中，许多颗粒和许多不同角度的测量被组合在一起，以允许提取通用弹性测量的解决方案CIJ。SRAS++将是一种极其快速和容易的测量方法，它将从以前看到的样本中学习。对于新的样品，测量CIJ只需几分钟，对于以前扫描的东西，CIJ将能够被实时测量，使其能够通过改变材料性质的过程，如热处理，完美地跟踪和监测这一重要测量。由于其独特的能力，SRAS++将成为材料科学中的重要测量手段，并帮助发现和开发重要的新材料。它在工业上也有很大的潜力来监控过程和评估部件的状况和状态，特别是安全关键部件。为了最大限度地发挥这一影响，我们与国际领先的材料科学家和先进行业团队合作，提供了五个具有挑战性的科学主题，以展示这一新测量技术的实用性和潜力。我们将为SRAS++开发一种专用仪器，它将比现有的SRAS机器快10-100倍。我们将通过利用新的激光技术来提高这台机器的空间分辨率，这将使我们能够在更广泛的材料上工作。这台专用机器，以及改进SRAS++求解器的工作计划，将使我们能够推动该技术已经处于世界领先地位的灵敏度，以便我们可以看到材料特性的越来越小的变化，这反过来将允许使用从样本中提取更多科学，并更详细地监控更多过程。

Many materials are polycrystalline, that is they are made up internally of lots of individual crystals of irregular shapes that have grown together. The class of polycrystalline materials includes nearly all metals and is therefore highly relevant to advanced engineering. The elasticity (three dimensional stiffness) of a individual crystals needs to be described by a six by six elasticity matrix, Cij rather than a single number. While Cij has 36 members, at most only 21 are independent and in most materials only around 1/2 dozen members are independent or non-zero. The elasticity of a material, Cij , is a fundamentally important in understanding not only the material's mechanical properties but other behaviours because it is directly influenced by the atomic arrangement inside the crystals.It is surprising to discover that there is no simple way to measure Cij in polycrystalline materials. Until the technique developed in this proposal, SRAS++, was invented, the only practical way to do this was to prepare a single crystal of the material and then measure Cij using that. However, preparing a single crystal of many of these materials is extremely difficult, slow and expensive. Furthermore, if a crystal is specially grown it is not truly representative of the real, bulk, polycrystalline material because the preparation conditions will be very different from the bulk. However, if the crystal is isolated from the bulk (a very difficult task) this damages the original specimen making it a poor technique to use on valuable materials or as a way to assess real products.In this proposal, we will develop a newly invented technique, SRAS++. This is based on a laser ultrasound imaging technique, SRAS, which uses surface acoustic waves to interrogate the crystals (grains) in the material. In SRAS++, measurements on many grains and at many different angles are combined together to allow a solution for common elasticity measurement, Cij , to be extracted. SRAS++ will be an extremely quick and easy measurement and it will learn from samples it has previously seen. For a new sample it will take a few minutes to measure Cij and for something that has been previously scanned, Cij will be able to be be measured in real time making it perfect to track and monitor this important measurement through processes that transform the materials properties, like heat treatments.Because of it's unique capability SRAS++ will become an important measurement in materials science and aid the discovery and development of important new materials. It also has great potential in industry to monitor processes and assess the condition and state of components, especially safety critical parts. To maximise this impact We have partnered with an internationally leading team of materials scientists and advanced industries to deliver five challenging science themes to demonstrate the utility and potential of this new measurement technique. We will develop a dedicated instrument for SRAS++ which will be 10-100 times faster than the existing SRAS machines. We will increase the spatial resolution of this machine by exploiting new laser technology that has become available which will allow us to work on a wider variety of materials. This dedicated machine, along with a program of work to improve the SRAS++ solver, will allow us to push the already world leading sensitivity of the technique so that we can see smaller and smaller changes in the material proprieties which, in turn, will allow use to extract more science from the samples and monitor more processes in more detail.