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 - 内存合金（HT-SMA）的特征在于100°C以上的转化温度。设想的应用是高温制度中的成本和资源有效的执行器和传感器。最有希望的HT-SMA是Co-Ni-GA，其特征是成本相对较低，功能性能优异，直至约500°C的温度以及转化应力对温度的低依赖性。然而，二-GA的潜力很难可加工，并且在晶粒尺寸和质地方面表现出了功能特性的强烈依赖性。在应用项目的范围内，应使用基于3D激光的直接能量沉积（DED）来克服以前的可加工性局限性并量身定制微观结构，从而在功能上分级的结构。通过局部叠加的超声波，不仅在几层层上而且在单层内创建不同的微观结构是可行的，从而为三维分级的结构提供了道路。合金的延展性以及转化温度将通过加工后的热处理改善。特别是，将通过将精度引入矩阵中来实现较低的转化温度，并且通过更改缩短顺序来实现较高的转换温度。综合的微观结构和功能表征，特别是通过原位方法，将使处理，微观结构和功能属性之间的关系具有基本见解。