EAGER: Controllable Synthesis of Gradient-Microstructured Materials, from the Nanoscale to Macroscale

梯度结构材料是表面具有纳米级结构，核心具有较粗结构的材料。与具有均匀粗晶或纳米晶结构的材料相比，这种材料表现出令人印象深刻的机械性能优势。然而，到目前为止，制造用于商业用途的梯度结构材料的能力尚未实现。该奖项支持对控制薄膜和块状材料微观结构的加工参数进行更深入的科学理解的研究，特别是探索性研究的早期概念资助（EAGER）奖将支持这些新型梯度结构的制造和合成的演示。制造这些结构的能力将允许对其行为进行科学研究，从这项研究中获得的新知识将使工程材料的设计具有更好的耐磨性和耐腐蚀性，并大大提高屈服强度和韧性。这项工作的好处将体现在汽车、航空航天和机床行业极端工程环境下部件的性能和产品寿命的提高上。这项早期工作的研究目标是探索新的加工方法来获得具有可控晶粒尺寸梯度的材料。为了实现薄膜和体样中晶粒尺寸梯度可控的目标，将对两种加工方法进行系统研究，具体目标是了解加工参数如何与梯度微观结构演变相关联。这些任务包括溅射制备具有定制层厚度、晶粒尺寸梯度和梯度界面的梯度钛薄膜，以及通过微观结构细化的数值模型对钛进行表面机械磨损处理。本研究的科学见解将为梯度微结构材料的加工条件对微观结构演变的影响提供更清晰的图像，并有助于更好地了解梯度纳米结构材料的可用性能空间，这可能会加速其在未来结构和涂层中的应用。

Gradient-structured materials are materials which have nanometer sized structure at the surface, and coarser structure at the core. Such materials have demonstrated impressive mechanical performance advantages over materials with homogeneous coarse-grained or nanocrystalline structures. So far, however, the ability to manufacture gradient structured materials for commercial use has not yet been realized. This award supports research to develop deeper scientific understanding of processing parameters that control the microstructures in both thin film and bulk materials, and in particular this EArly-concept Grant for Exploratory Research (EAGER) award will support demonstration of the fabrication and synthesis of these novel gradient structures. The ability to fabricate these structures will allow for scientific investigation of their behavior, and the new knowledge gained from this research will enable the design of engineered materials with improved resistance to wear and corrosion, and also drastically improved yield strength and toughness. The benefits of this work will manifest in improved performance and product lifetimes for components subjected to extreme engineering environments in automotive, aerospace and machine tools industries.The research objective of this early-stage work is to explore novel processing approaches for obtaining materials with controllable grain size gradients. To realize the goal of controllable grain size gradients in both thin-film and bulk samples, a systematic investigation of two processing approaches will be carried out, with the specific goal of understanding how processing parameters can be correlated with gradient microstructural evolution. These tasks include sputtering fabrication of gradient titanium thin-films with tailored layer thicknesses, grain size gradients, and graded-interfaces, and surface mechanical attrition treatment of titanium informed by numerical models of microstructural refinement. The scientific insights stemming from this research will provide a clearer picture on the effect of processing conditions on the microstructural evolution of gradient microstructure materials, and facilitate a better understanding of the property space available for gradient nanostructured materials, which may accelerate insertion into future structural and coating applications.