Study of aluminium alloys addressing aspects of manufacturing, oxide formation, and recycling

铝及其合金已应用于各种工业领域，如建筑、能源、包装、船舶、航空航天和汽车。铝具有一系列独特的吸引人的特性：(i)铝重量轻，比密度为2.70 gcm-3，约为钢（7.83 gcm-3）的三分之一，对低能耗的持续需求使其成为部件中较重合金的理想替代品（ii）可以铸造和机械加工；（iii）铝的强度可以通过改变其合金的成分和显微组织来适应不同的应用。一些新型铝合金和铝基复合材料由于具有应对极端条件的潜在能力，例如高温和高压，最近受到了相当大的关注。这可以通过添加合金，为所需的析出物定制合金成分和添加合适的增强剂来实现。该项目的最终目标是将这些非常专业、高强度、轻质的纳米准晶铝合金（具有非常好的高温强度）与更传统的铝合金结合在一起。这是为了使极少量非常昂贵的纳米准晶合金的使用成为可能，只将这种合金放置在部件中需要这些性能的位置。汽车发动机活塞的顶面就是一个例子。为了做到这一点，我们需要提高对铝合金氧化的热力学和动力学的理解，作为组成和加工的函数。铝很容易氧化，并可以采取许多不同的氧化物的形式，无定形和晶体，颗粒或薄膜形态或组合。氧化物的存在抑制键合，但对氧化物性质的处理可以改善键合。牛津大学材料系有很多先进的分析技术，可以用来研究氧化的速度、形成的氧化物的厚度以及形成的氧化物的结晶类型、成分和形态。我们可能是世界上第一个成功地将铝从氧化物中溶解出来的实验室，因此可以使用电子显微镜技术详细观察氧化层两侧的三维形态。这项工作的总体目标是通过先进的表征技术和模拟热力学和动力学参考点的结果，全面了解氧化对不同铝合金键合的作用。这将导致对稳定氧化物和界面键（即氧化双分子层）的性质和完整性的预测，这将有助于对氧化物和界面氧化双分子层进行裁剪，以实现所需的键。该项目属于EPSRC制造未来研究领域。

Aluminium (Al) and its alloys have been applied in various industry sectors, such as construction, energy, packaging, marine, aerospace and automotive. Al has a unique combination of attractive properties: (i) Al is lightweight with a specific density of 2.70 gcm-3, about a third that of steel (7.83 gcm-3), and the continuous demand for lower energy consumption has made it an ideal candidate to substitute for heavier alloys in components (ii) can be cast and machined; (iii) the strength of Al can be adapted to different applications by modifying the composition and hence the microstructure of its alloys. Some novel Al alloys and Al matrix composites have recently been receiving considerable attention due to their potential ability to cope with extreme conditions, such as elevated temperatures and high pressures. This can be achieved by alloying additions, tailoring the alloy compositions for desired precipitates and adding suitable reinforcements. The ultimate aim of the project is to bond together these very specialist, high strength, lightweight nano-quasicrystalline aluminium alloys which have very good high temperature strength, with a more conventional aluminium alloy. This is to enable the use of minimum quantities of the very expensive nano-quasicrystalline alloy, by placing this alloy only in the locations in a component which require these properties. An example would be the top surface of a piston for an automotive engine. In order to do this we need an improved understanding of the thermodynamics and kinetics of the oxidation of aluminium alloys as a function of composition and processing. Aluminium oxidises very readily and can take the form of a number of different oxides, amorphous and crystalline, in particle or film morphologies or in combinations. The presence of an oxide inhibits bonding but manipulation of the nature of the oxide can improve the bonding. The Department of Materials here at the University of Oxford has access to a number of sophisticated analysis techniques which can be used to investigate the rate of oxidation, the thickness of the oxides formed and the crystalline-types, compositions and morphologies of the oxides formed. We are perhaps the first laboratory in the world to have successfully dissolved away the aluminium from the oxide, so allowing detailed observation of the three-dimensional morphology of both sides of the oxide layer using electron microscopy techniques.The overall aim of the work is to provide a comprehensive understanding of the role of oxidation on the bonding of different Al alloys through advanced characterization techniques and simulating the results from thermodynamic and kinetic points of reference. This will lead to the prediction of stable oxides and the nature and integrity of the interfacial bond, i.e., oxide bilayer, which will facilitate the tailoring of oxides and the interfacial oxide bilayers in order to achieve the desired bond.This project falls within the EPSRC Manufacturing the future research area.