Functionally graded Co-Ni-Ga high-temperature shape memory alloys manufactured via ultrasound assisted 3D laser-based directed energy deposition

通过超声辅助 3D 激光定向能量沉积制造的功能梯度 Co-Ni-Ga 高温形状记忆合金

• 批准号: 507664574
• 负责人: Professor Dr.-Ing. Stefan Böhm
• 金额: --
• 依托单位: Fachgebiet für Trennende und Fügende Fertigungsverfahren
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/507664574?language=en
• 关键词: Functionally; graded; Co; Ni; Ga

High-temperature shape-memory alloys (HT-SMAs) are characterized by transformation temperatures above 100 °C. Envisaged applications are cost- and resource-efficient actuators and sensors in a high temperature regime. One of the most promising HT-SMAs is Co-Ni-Ga, which is characterized by comparatively low costs, excellent functional properties up to temperatures of about 500°C and a low dependency of transformation stresses on temperature. However, Co-Ni-Ga possess a difficult workability and shows a strong dependency of functional properties with respect to grain size and texture. Within the scope of the applied project, 3D laser-based direct energy deposition (DED) should be used to overcome previous limitations of workability and to tailor microstructural and, thus, functionally graded structures. By locally superimposed ultrasonic waves, it will be feasible to create different microstructures not only over several layers but also within a single layer, thus paving the way for three-dimensionally graded structures. The ductility of the alloy as well as the transformation temperatures will be improved by post processing heat treatments. In particular, lower transformation temperatures will be realized by introducing precipitates into the matrix and higher transformation temperatures will be realized by changing the shortrange order. A comprehensive microstructural and functional characterization, in particular by means of in situ methods, will enable elementary insights in the relation between processing, microstructure and functional properties.

高温形状记忆合金（HT-SMA）的特征在于相变温度高于100 °C。设想的应用是在高温状态下具有成本和资源效率的致动器和传感器。最有前途的HT-SMA之一是Co-Ni-Ga，其特征在于相对较低的成本，高达约500°C的温度的优异功能特性以及相变应力对温度的低依赖性。然而，Co-Ni-Ga具有困难的可加工性，并且显示出相对于晶粒尺寸和织构的功能性质的强依赖性。在应用项目的范围内，基于3D激光的直接能量沉积（DED）应用于克服以前的限制，可加工性和定制微观结构，因此，功能梯度结构。通过局部叠加超声波，不仅可以在几个层上而且可以在单个层内创建不同的微观结构，从而为三维梯度结构铺平道路。合金的延展性以及转变温度将通过后加工热处理来改善。特别地，通过向基体中引入沉淀物将实现较低的相变温度，并且通过改变短程有序度将实现较高的相变温度。全面的微观结构和功能表征，特别是通过原位方法，将使加工，微观结构和功能特性之间的关系的基本见解。