Diffusion in High Entropy Alloys

采用新的示踪剂-互扩散偶技术研究了高熵合金中的扩散，并基于对扩散概念建立了扩展的示踪剂扩散数据库。 虽然在第一个资金周期的重点放在建立的实验和理论技术以及一般的数据库开发，拟议的扩展旨在系统地研究示踪剂相互扩散耦合方法占各种情况下，可能会遇到在真实的多主元素合金，包括充分的可溶解性，相形成，复杂的相互扩散路径，和强大的体积变化。同时，多组分HEAs中扩散的模型描述必须扩展到将空位作为单独的物种来考虑，随着不同子晶格的出现而有序化，实验分析和理论描述的方法的阐述将以一种协调一致的方式进行，应用一个组合的实验-我们的研究是出于迫切需要提供可靠的动力学数据库，充分预测扩散现象的多主元素合金，包括HEAs和成分复杂的合金（CCA）。此外，我们还将开发原子迁移率的自动评估软件，并将其与新型迁移率数据库联合收割机相结合。在SPP 2006 CCA-HEA框架内与合作伙伴进行的密切而富有成效的互动将激励和支持我们的见解和方法转移到其他材料类别，特别是BCC HEA和选定的CCA。

Diffusion in High Entropy Alloys (HEAs) is investigated using novel tracer-interdiffusion couple technique and compiled in an extended tracer diffusion database based on the pair-diffusion concept. While in the first funding period the focus lay on the establishment of the experimental and theoretical techniques as well as the general data base development, the proposed extension aims to examine systematically the tracer-interdiffusion couple method accounting for various situations which may be met in real multi-principal element alloys, including full miscibility, phase formation, complex interdiffusion paths, and strong volumetric changes. Simultaneously, the model description of diffusion in multicomponent HEAs has to be extended to account for vacancies as a separate species, ordering with appearance of different sub-lattices, influence of interstitially dissolved atoms and molar volume change along the interdiffusion path. The elaboration of the methodologies of experimental analysis and theoretic description will be done in a concerted way applying a combined experiment-modelling ansatz based on the CALPHAD-type description and the developed pair-wise diffusion model.Our research is motivated by the urgent need to provide reliable kinetic databases for adequate prediction of diffusion phenomena in multi-principal element alloys including both HEAs and compositionally complex alloys (CCAs). Furthermore, we will develop an automated assessment software for atomic mobilities and combine with the novel mobility database.A close and fruitful interaction with partners in the framework of SPP 2006 CCA-HEA will motivate and support the transfer of our insights and methods to other material classes and in particular to BCC HEAs and selected CCAs.