New Quinary and Senary High Entropy Shape Memory Alloys (HE-SMA) – Exploring and Exploiting Martensitic Transformations and Shape Memory Effects in Chemically Complex Systems

拟议的研究重点是理解和利用高熵形状记忆合金（HE-SMA）的行为的机制。长期目标是将这些材料建立为具有广泛应用潜力的一类新的工程合金。三个科学目标的特点拟议的研究。合金开发活动是基于一种新的筛选方法，以开发新的五元和六元形状记忆合金。这种连续的背景活动涉及高精度熔化活动，并解决了研究沿着锭冶金加工链的微观结构演变的需要，包括（i）控制六种熔体的凝固和（ii）在铸造后热机械处理期间发生的过程。三个科学目标可以简要描述如下：首先，确定HE-SMA的新组合物，其在高转变温度、大形状记忆应变和良好功能稳定性方面优于传统SMA。其次，使用先进的表征方法（除了标准方法：先进的分析高分辨率SEM和TEM，原子探针断层扫描），以澄清化学复杂性对控制和影响马氏体相变的基本转变和变形过程的影响。第三个目标旨在推进形状记忆技术。本部分重点研究化学复杂性对相关形状记忆效应（单向效应，伪弹性）的影响，旨在开发HE-SMA演示器，该演示器允许欣赏和量化弹簧致动器的功能性能。在拟议的工作的基础部分，开放的问题，从两个迷人的研究领域高熵合金和形状记忆合金的联系。具体而言，将探索化学复杂性影响HE-SMA的机械和功能特性的方式，以及如何利用化学复杂性来促进HE-SMA技术。从技术的角度来看，挤压加工将应用于成分复杂的HE-SMA，这有望为材料提供进一步增加的延展性。此外，弹簧致动器将建立和特点，特别关注功能疲劳，这限制了所有形状记忆合金的可利用的使用寿命。本提案中提出的工作方案被细分为11个明确界定的工作包，其中一个工作包专门用于与其他SPP项目的互动。

The proposed research focusses on understanding and exploiting the mechanisms that govern the behavior of high entropy shape memory alloys (HE-SMAs). The long-term objective is to establish these materials as a new class of engineering alloys, which have potential for wide spread applications. Three scientific objectives characterize the proposed research. The alloy development activity is based on a novel screening approach in order to develop new quinary and senary shape memory alloys. This continuous background activity involves high precision melting activities and addresses the need to study the microstructural evolution along the ingot metallurgy processing chain, including the processes that (i) govern the solidification of senary melts and (ii) occur during post-cast thermo-mechanical treatments. The three scientific objectives can be briefly described as follows: Firstly, to identify new compositions for HE-SMAs that outperform conventional SMAs in terms of high transformation temperatures, large shape memory strains and good functional stability. Secondly, to use advanced characterization methods (in addition to standard methods: advanced analytical high-resolution SEM and TEM, atom probe tomography) to clarify the effect of chemical complexity on the elementary transformation and deformation processes that govern and affect the martensitic phase transitions. The third objective aims at advancing shape memory technology. This part focuses on studying the influence of chemical complexity on the relevant shape memory effects (one-way effect, pseudoelasticity) and aims at developing a HE-SMA demonstrator, which allows appreciating and quantifying the functional performance of a spring actuator. In the fundamental part of the proposed work, open questions from the two fascinating research areas high entropy alloys and shape memory alloys are linked. Specifically, the way in which chemical complexity affects mechanical and functional properties of HE-SMAs and how chemical complexity can be exploited to promote HE-SMA technology will be explored. From a technological point of view, extrusion processing will be applied to compositionally complex HE-SMAs, which promises to provide materials with further increased ductility. Moreover, a spring actuator will be built and characterized, with a special focus on functional fatigue, which limits the exploitable service life of all shape memory alloys. The work programme proposed in this proposal is subdivided into 11 well-defined work packages, one of which is devoted to the interaction with other SPP projects.