SRAS++ single crystal elasticity matrix measurement in polycrystalline materials

许多材料都是多晶的，也就是说，它们的内部是由许多不规则形状的单个晶体生长在一起组成的。多晶材料几乎包括所有金属，因此与先进工程高度相关。单个晶体的弹性（三维刚度）需要由6 × 6弹性矩阵Cij而不是单个数字来描述。虽然Cij有36个成员，但最多只有21个是独立的，在大多数材料中，只有大约1/2的成员是独立的或非零的。材料的弹性Cij不仅对理解材料的机械性能，而且对理解其他行为都至关重要，因为它直接受到晶体内部原子排列的影响。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，然后使用它测量Cij。然而，制备许多这些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，则其不能真正代表真实的块状多晶材料，因为制备条件将与块状材料非常不同。然而，如果晶体从块体中分离出来（这是一项非常困难的任务），这会损坏原始样品，使其无法用于有价值的材料或评估真实的产品。在本提案中，我们将开发一种新发明的技术SRAS++。这是基于激光超声成像技术，SRAS，它使用表面声波来询问材料中的晶体（晶粒）。在SRAS++中，对许多颗粒和许多不同角度的测量被组合在一起，以允许提取常见弹性测量Cij的解决方案。SRAS++将是一个非常快速和简单的测量，它将从以前看到的样本中学习。对于新样品，测量Cij需要几分钟时间，而对于之前已经扫描过的样品，Cij将能够在真实的时间内测量，从而完美地通过改变材料特性的过程来跟踪和监控这一重要测量，SRAS++的独特性能使其成为热处理的首选。将成为材料科学中的重要测量手段，有助于重要新材料的发现和开发。它在工业中也有很大的潜力来监控过程和评估组件的状况和状态，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，提供五个具有挑战性的科学主题，以展示这种新测量技术的实用性和潜力。我们将为SRAS++开发专用仪器，其速度将比现有的SRAS仪器快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。这台专用的机器，沿着一个工作计划，以改善SRAS++求解器，将使我们能够推动已经世界领先的技术灵敏度，使我们可以看到越来越小的变化，在材料属性，这反过来，将允许使用提取更多的科学从样品和监测更多的过程更详细。

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.