Investigation of the phase boundary and site occupation of atoms in pure and doped TiAl/Ti3Al intermetallic by means of the tomographic atom probe (TAP)

利用断层扫描原子探针 (TAP) 研究纯 TiAl/Ti3Al 金属间化合物中原子的相界和位置占据

• 批准号: 5397246
• 负责人: Professor Dr. Reiner Kirchheim, since 4/2010
• 金额: --
• 依托单位: Institut für Materialphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5397246?language=en
• 关键词: Investigation; phase; boundary; site; occupation

Dual-phase Ti-Al alloys with lamellar structure, comprising g-phase plus a small amount of a2-phase, have a great potential application as high temperature materials. Alloying addition of Nb is very effective in improving strength and oxidation resistance of these alloys, however, the impact of Nb-addition on the microstructure development and consequently, on the mechanism of these improvements has not been clarified yet. 3D-tomographic atom probe (TAP) is a powerful tool to gain detailed characterization of the microstructures on the atomic scale. In this proposal, dual-phase TiAl/T3Al alloys with addition of 0-5at%Nb will be investigated by means of TAP and supporting TEM, HRTEM and TEM in-situ tensile testing. The impacts of Nb-alloying addition on the variation of different microstructural parameters, such as lamellar size, composition of the two phases, boundary structures, will be reported. The Nb-atomic site occupancies in TiAl- and Ti3 Al-phases, as well as any clustering and/or ordering of Nb atoms will be revealed. The possible segregation or depletion of Nb-atoms at grain boundaries, interphase boundaries and twist boundaries will be elucidated. On the bases of these experiments the mechanism of improvement in both strength and oxidation resistance by Nb alloying addition in these alloys will be modeled.

片层结构的双相Ti-Al合金由g相和少量的α2相组成，在高温材料方面具有很大的应用潜力。添加Nb合金化对提高合金的强度和抗氧化性是非常有效的，但添加Nb对组织发展的影响以及对其改善机制的影响尚不清楚。三维层析原子探头(TAP)是在原子尺度上对微观结构进行详细表征的有力工具。在本方案中，将通过TAP和支撑的透射电子显微镜、高分辨透射电子显微镜和透射电子显微镜原位拉伸试验来研究添加0-5AT%Nb的双相TiAl/T3Al合金。研究了Nb合金化对片层尺寸、两相组成、晶界结构等不同组织参数变化的影响。将揭示Nb原子在TiAl和Ti3Al相中的位置，以及Nb原子的任何聚集和/或有序性。Nb原子在晶界、相间晶界和扭曲晶界可能的偏聚或贫化将被阐明。在这些实验的基础上，模拟了在这些合金中添加Nb合金提高强度和抗氧化性的机理。