Dynamic Grain Growth in BCC Metals and Alloys

1.金属及其合金对于生产支持现代社会的复杂机器所需的结构部件至关重要。 金属结构部件的例子在汽车、飞机、桥梁和建筑物中显而易见。 不太明显的是这些材料内部的微观特征，这些特征控制着它们的性能，使它们能够有效地用于最苛刻的任务，这些特征统称为微观结构。 微观结构包括晶粒，金属的小的单个晶体，其决定强度，延展性和其他材料特性。 如果要实现其技术应用所需的性能，则必须在每个部件的制造过程中控制晶粒结构。 该项目旨在建立关于金属在高温下变形时晶粒如何发展和生长的科学，这是各种金属制造操作中的重要加工步骤。 在这些条件下的晶粒生长称为动态晶粒生长。 该项目产生的新认识预计将对未来金属成型的制造实践产生积极影响。 通过参与这项科学调查，对研究生和本科生进行了培训。 该项目的一个组成部分是与ASM国际合作，加强研究成果的公开传播，以便有价值的数据能够对科学和工程界以及更广泛的社会产生最积极的影响。动态晶粒生长是一个对金属和合金加工具有重要技术意义的课题。 然而，它也是金属科学中的一个主题，我们对此只有非常有限的了解。 该实验研究项目旨在对导致动态晶粒生长的机制产生新的理解，更好地确定为什么动态和静态情况下的晶界迁移行为不同，并将这些新的理解组织起来，以积极影响制造技术。 体心立方金属中动态晶粒长大的机制是主要的焦点。 动态异常晶粒生长和动态正常晶粒生长。 所研究的材料包括难熔金属、钼和钽以及铁基合金。 铁基合金包括商业上重要的无磷钢，它为科学研究提供了近乎理想的模型材料，也是一种与技术相关的材料。 实验的目的是测试新的假设动态正常和动态异常晶粒生长之间的关系，探测现有的假设动态条件下的晶界的流动性，并探讨目前没有假设存在的问题。 实验方法包括独特的机械测试，现代表征技术，先进的计算机数据分析技术和通过数值模型的解释。

1. Nontechnical AbstractMetals and their alloys are critically important to the production of structural components required in the complex machines supporting modern society. Examples of metallic structural components are readily evident in automobiles, aircraft, bridges and buildings. Less obvious are the microscopic features inside these materials that control their properties and enable them to effectively serve in the most demanding tasks, features that are collectively called the microstructure. The microstructure includes grains, small individual crystals of the metal, that determine strength, ductility and other material properties. The grain structure must be controlled during manufacturing of each component if it is to achieve the properties required for its technological application. This project seeks to build the science of how grains develop and grow while metals are deformed at elevated temperatures, an important processing step in a wide variety of metals manufacturing operations. The growth of grains under these conditions is called dynamic grain growth. The new understanding produced under this project is expected to positively impact future manufacturing practices for the forming of metals. Through participation in this scientific investigation, students at the graduate and undergraduate levels are trained. An integral aspect of this project is a partnership with ASM International on enhancing the open dissemination of research results so that valuable data can most positively impact the scientific and engineering communities, as well as broader society.2. Technical AbstractDynamic grain growth is a topic of great technological importance to the manufacture of wrought metal and alloy products. Yet, it is also a topic within metals science for which we have only a very limited understanding. This experimental research project seeks to produce new understanding for the mechanisms that cause dynamic grain growth, better establish why grain boundary migration behaviors are different between the dynamic and static cases, and organize these new understandings to positively impact manufacturing technologies. The mechanisms responsible for dynamic grain growth in body-centered-cubic metals are a primary focus. Both dynamic abnormal grain growth and dynamic normal grain growth are addressed. The materials studied include the refractory metals, molybdenum and tantalum, and iron-based alloys. The iron-based alloys include commercially important interstitial-free steels, which provide both a nearly ideal model material for scientific investigation and a material of technological relevance. Experiments are designed to test new hypotheses for the relationship between dynamic normal and dynamic abnormal grain growth; probe existing hypothesis for the mobility of grain boundaries under dynamic conditions; and explore questions for which no hypotheses currently exist. Experimental methods include unique mechanical testing, modern characterization techniques, advanced computerized data analysis techniques and interpretation through numerical models.