GOALI: Dissimilar Metal Joining for Micro-Scale Medical Devices

GOALI学术联系机会奖的研究目标是研究一种新的连接方法--自生(无填充材料)激光铜焊，用于连接不同的生物兼容金属。具体地说，该项目的目的是通过考虑工艺的热、动力学和热力学方面来加深对自体激光钎焊接头的基本了解，通过实验和数值研究非平衡工艺条件对焊缝金属混合物的热力学性质的影响及其对所产生的相和界面微观结构的影响，并显著增强对不同材料对中金属间相形成的知识，并探索减轻或消除这些相的潜在途径。预计解决这一问题的方法是限制材料的混合，并在不使用填充材料的情况下快速冷却熔融金属。将对相、显微组织和强度进行表征。研究结果将验证由有限冷却速率相形成和空间分辨成分计算组成的建模工作。该项目的好处有望使创新的植入式医疗设备的设计和制造成为可能，这些设备选择性地结合具有独特性能的生物兼容金属，以显著提高设备性能或引入突破性功能。加入这些材料的需要源于希望以坚固和具有成本效益的方式整合其独特的特性。然而，阻碍异种金属接头广泛使用的主要障碍是接头内形成的脆性金属间化合物相。PI得到了一个关键工业合作伙伴的大力支持，可能会导致这些设备在现实生活中的应用迅速发展，具有广泛的社会影响。本项目为生物相容性金属对开发的加工技术、分析方法和预测能力可推广到飞机结构和汽车电池应用的其他材料对。

The research objective of this Grant Opportunity for Academic Liaison with Industry (GOALI) award is to investigate a novel joining process, autogenous (no filler material) laser brazing, for joining dissimilar biocompatible metals. Specifically, the project aims to develop a fundamental understanding of autogenous laser brazed joints by considering the thermal, kinetic, and thermodynamic aspects of the process, to experimentally and numerically investigate the effect of non-equilibrium processing conditions on the thermodynamic properties of the weld metal mixture and their effect on the resulting phases and interface microstructures, and to significantly enhance the knowledge of intermetallic phase formation in dissimilar material pairs and investigate potential avenues for their mitigation or elimination. The projected approach to address this issue is by limiting mixing of the materials and rapidly cooling the molten metal without the use of filler materials. Phase, microstructure, and strength will be characterized. The results will validate the modeling efforts which will consist of finite cooling rate phase formation and spatially resolved composition calculations.The benefits of this project are expected to enable the design and fabrication of innovative, implantable medical devices that selectively incorporate biocompatible metals with unique properties to significantly enhance device performance or introduce groundbreaking functionalities. The need to join these materials stems from the desire to integrate their unique properties in a robust and cost-effective manner. The main impediment to widespread use of dissimilar metal joints, however, is the formation of brittle intermetallic phases within the joints. The PI's strong support by a key industrial partner could lead to rapid development of real life applications of these devices with broad societal impact. The processing techniques, analysis methods, and predictive capabilities developed for the biocompatible metal pairs addressed in this project can be extended to other material pairs for aircraft structure and automobile battery applications.