Diffusion in high entropy alloys: Development and application of an experiment-ab initio approach

高熵合金中的扩散：从头开始实验方法的开发和应用

• 批准号: 397350460
• 负责人: Professor Dr. Sergiy Divinski
• 金额: --
• 依托单位: Max-Planck-Institut für Eisenforschung GmbH (MPIE)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/397350460?language=en
• 关键词: Diffusion; entropy; alloys; Development; application

Reliable control over phase decomposition and creep behavior of high entropy alloys (HEAs) represents an enormous challenge in view of their multi-principal element nature and presumably slow diffusion. The present project DIFFINITIO aims at tackling this challenge from a fundamental perspective by developing and applying an integrated experiment-ab initio approach for the determination of accurate diffusion coefficients in HEAs. The proposal relies on the leading and unique expertise of the applicants in the fields of radiotracer diffusion measurements and finite temperature ab initio computations. With our investigations we will provide fundamental insights into the basic atomistic mechanisms of diffusion in HEAs, quantifying the impact of the multi-element environment, and scrutinizing postulated concepts as the one of sluggish diffusion.We focus on a specific, non-magnetic material system, the AlHfScTiZr HEA. AlHfScTiZr crystallizes on the hcp lattice and may develop sublattices ordering depending on the Al concentration. The temperature dependencies of the self-diffusion rates of all principal elements (with Zn as Al substitute) in the selected AlHfScTiZr HEA will experimentally be determined and evaluated from the DFT-based barrier calculations and the cluster expansion-based kinetic Monte carlo simulations enabling direct a direct quantification of the correlation and short-range ordering effects. The sublattice ordering is a fascinating feature because it affects strongly self-diffusion and solute diffusion rates. Preliminary investigations show clearly that small transition-metal elements like Ni are ultrafast interstitial diffusers in this alloy. Their diffusion rates are higher than those expected for self-diffusion by four orders of magnitude. This is counterintuitive and the mechanism behind the ultrafast diffusers is not clarified so far. As a part of the proposal, we suggest to develop a unique and extremely sensitive experimental tool for addressing the early stages of phase decomposition and formation and evolution of ordering, making use of the phenomenon of ultrafast diffusion. A significant advance in the basic understanding of fundamental HEA concepts is expected with the accomplishment of the DIFFINITIO project, especially in view of the present absence of reliable diffusion data for this material class in the literature.

鉴于它们的多主体元素性质和大概缓慢的扩散，对高熵合金（HEAS）的相位分解和蠕变行为的可靠控制代表了巨大的挑战。本项目的差异旨在通过开发和采用综合实验启动方法来确定HEAS中准确的扩散系数，从而从基本角度来应对这一挑战。该提案依赖于放射性扩散测量和有限温度从头算计算的领域中申请人的领先和独特专业知识。通过我们的研究，我们将提供对HEAS扩散基本原子学机制的基本见解，量化多元元素环境的影响，并审查假定的概念作为缓慢的扩散之一。 alhfsctizr在HCP晶格上结晶，可能会根据Al浓度而产生sublattices排序。从基于DFT的屏障计算和基于群集的基于群集的蒙特卡洛模拟，可以直接直接量化相关性和短距离订购效果，从实验确定并评估了所选ALHFSCTIZR HEA中所有主要元素（作为Al替代）的自扩散率的温度依赖性。 Sublattice Ordering是一个引人入胜的功能，因为它会影响强烈的自扩散和溶质扩散率。初步研究清楚地表明，像NI这样的小型过渡金属元素是该合金中超快的间隙扩散器。它们的扩散率高于四个数量级的自我扩散期望的扩散率。这是违反直觉的，到目前为止，尚未阐明超快扩散器背后的机制。作为提案的一部分，我们建议开发一种独特且极其敏感的实验工具，以解决相位分解的早期阶段，形成和订购的演变，利用超快扩散现象。通过完成Diffinitio项目的成就，预计对基本HEAT概念的基本理解的重大进步，尤其是考虑到目前的文献中该材料类别的可靠扩散数据。