The Determination of Activation Energies and Modeling of Low Temperature (<0.25Tm) Creep Behavior of Alpha, Alpha-Beta and Beta Titanium Alloys

技术：钛合金正在寻找低温(0.25Tm)的应用，例如在核废料储存的滴漏屏蔽中，蠕变行为可能起到重要作用。为了在这些应用中有效地使用钛合金和设计新的合金，需要更好地了解变形机制和微观组织之间的关系。该小组过去的研究重点包括确定贝塔钛合金蠕变的激活能，发展随时间变化的孪晶的结晶学模型，以及确定两相钛合金新变形机制的透射和高分辨率电子显微镜研究。尚未解决的问题包括α-α钛合金中如何发生随时间变化的孪晶，为什么α-β钛合金中会出现新的变形机制，以及形态和变形机制之间的关系。解决这些问题是本次调查的主题。研究包括三维各向异性有限元建模，以确定α和β相之间的相互作用。这项研究的结果是建立了包含钛的变形机制、微观结构和晶体结构的模型。非技术性：虽然模型体系是钛合金，但研究结果应该适用于其他合金体系，特别是锆合金体系。本次调查涉及研究生和本科生，学生将学习机械测试、传输和高分辨率电子显微镜等实验技能，以及数据分析和技术报告撰写技能。此外，还将千方百计招收少数民族学生。这位资深研究员是TMS/ASM学生分会的创始教师顾问；在过去的四年里，该分会获得了“卓越章节”奖。本分会参加全国专业学会会议，教育高中生到大学开放参观，以及部门教育活动。

TECHNICAL: Titanium alloys are finding low temperature (0.25Tm) applications, such as in drip shields for nuclear waste storage where creep behavior can play an important role. For effective use of titanium alloys in these applications and to design new alloys, the relationships between deformation mechanisms and microstructures need to be better understood. Past research highlights by this group include determination of the activation energy for creep of beta titanium alloys, development of crystallographic models for time-dependent twinning, and transmission and high-resolution electron microscopy studies that identify new deformation mechanisms in two-phase titanium alloys. Unresolved issues include how time-dependent twinning occurs in ?alpha titanium alloys, why new deformation mechanisms occur in alpha-beta titanium alloys and the relation between morphology and deformation mechanisms. Addressing these issues is the subject of this investigation. The investigation includes 3-dimensional, anisotropic finite element modeling to determine the interaction between alpha and beta phases. An output of this investigation is modeling that incorporates deformation mechanisms, microstructure, and crystal structure in titanium. NONTECHNICAL: Although the model systems are titanium alloys, the research results should be applicable to other alloy systems, in particular those of zirconium. This investigation involves both graduate and undergraduate students and the students will learn experimental skills such as mechanical testing, transmission and high-resolution electron microscopy, as well as data analysis and technical report writing skills. In addition, every attempt will be made to recruit minority students. The senior researcher is the founding faculty advisor for the TMS/ASM student chapter; the last four years the chapter received the "Chapter of Excellence" award. This chapter participates in national professional society meetings, educating high school students who come to open houses at the university, and the departmental educational activities.