Collaborative Research: Revealing the Role of Vacancy Order in Regulating the Dislocation Behavior in Transition Metal Carbides

非技术描述：过渡金属碳化物是一类用途广泛的陶瓷，包括切割材料、核能和涂层。这些应用使这些材料同时承受温度和机械载荷，它们在使用中必须承受这些载荷。本项目研究化学和晶体结构在控制这些性质的机械机制中的作用。通过这个项目，研究生将被训练来测试、表征、模拟和预测过渡金属碳化物的机械行为。这些学生通常在社会的能源、国防和航空航天部门找到工作。此外，该项目还开发了中学教育学习模块，向初中生和高中生解释硬度的技术定义。技术细节：众所周知，过渡金属碳化物具有独特的机械性能，这些性能与其化学和结构密切相关。这个项目调查了这种化学，特别是碳原子的有序性，是如何控制这些碳化物中导致特殊异常硬化和低温蠕变的机械机制的。实验和计算研究为阐明这些陶瓷中位错的基本机制提供了协同支持，这些机制与温度、化学以及最重要的非金属亚晶格的有序性有关。该项目首次使用序数参数以化学顺序的形式描述了力学性能。考虑到这些材料在能源、航空航天和国防工业中的重要性，特别是在应用高超声速领域，这个项目现在特别重要。此外，了解这些力学性能的机械联系将有助于开发新的成分复杂的过渡金属碳化物。鉴于研究的性质，研究生在两个互补的领域--高级材料表征和材料建模--以综合方式进行培训。这项研究通过由研究人员领导的关于陶瓷变形机制的研讨会进一步加强了这一领域。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Transition metal carbides are a class of ceramics that have a wide range of uses including cutting materials, nuclear energy, and coatings. These applications subject these materials to both temperature and mechanical loads, which they must withstand in service. This project investigates the role of chemistry and crystal structure in controlling the mechanical mechanisms responsible for these properties. Through this project, graduate students will be trained to test, characterize, model and predict the mechanical behavior of transition metal carbides. Those students typically find employment in the energy, defense, and aerospace sectors of society. In addition, this project develops secondary education learning modules that explain hardness, as a technical definition, to middle and high school students.TECHNICAL DETAILS: The transition metal carbides are known to have unique mechanical properties which are intimately linked to their chemistry and structure. This project investigates how this chemistry, and specifically the order of the carbon atoms, controls the mechanical mechanisms responsible for peculiar anomalous hardening and low temperature creep in these carbides. The experimental and computational research develops synergic support in elucidating the fundamental mechanics of dislocations in these ceramics relative to temperature, chemistry, and most importantly, the order of the non-metal sublattice. This project provides, for the first time, a description of the mechanical properties in terms of chemical order using the order parameter. This project is particularly relevant now given the importance of these materials for use in the energy, aerospace, and defense industries, especially the area of applied hypersonics. Furthermore, understanding the mechanistic link for such mechanical properties will aid the development of new compositionally complex transition metal carbides. Given the nature of the research, the graduate students are trained in an integrated manner for the two complementary areas - advanced materials characterization and materials modeling. This research further enhances the field through symposiums led by the investigators on the deformation mechanisms in ceramics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.