大块非晶合金在搅拌摩擦焊过程中塑性流动行为研究

The two drawbacks of bulk metallic glasses (BMGs) parts, including small size and simple shape, can be overcomed by metallurgical bonding the BMGs with friction stir welding (FSW) technique. However, the flow behavior which decides the joint quality of BMGs during the FSW process has not been currently reported..In this project, Cu36Zr48Ag8Al8 BMGs with excellent mechanical performance will be chosen as research object. In order to analysis and summary the plastic flow behavior of BMGs in the supercooled liquid region under high strain rate, flow behaviors of different FSW welding joints during the FSW process will be observed using material tracing technique, including perfect joint, joint with tunnel defects and joint with cavity defects. Then microstructure and mechanical properties of the BMGs joints will be compared. The mechanism and influence rule of plastic flow behavior on microstructure and mechanical properties of the joints will be researched. In addition, related model will be set up, which can guide the production practice..The works will help us to reveal the forming mechanism of FSW joint and make clear microstructure evolution rule of BMGs during the FSW process. The forming conditions of FSW joint with high quality will also be defined. The results will promote the industrialization process of BMGs, which will be of great significance to the theoretical value and engineering application.

采用搅拌摩擦焊（FSW）实现大块非晶合金（BMGs）之间的连接，可以克服BMGs制件尺寸小、形状简单两大难题。然而，在FSW过程中，对接头质量起决定作用的金属塑性流动行为的研究目前未见报道。.本项目以综合性能优异的Cu36Zr48Ag8Al8 BMGs为研究对象，采用示踪材料法，分别对不同形态的FSW焊接接头（无缺陷接头、隧道型缺陷接头及空洞缺陷接头）在形成过程中的金属塑性流动行为进行跟踪观察，分析总结非晶合金在高应变速率条件下的过冷液相区塑性流动行为。然后，通过焊接接头的显微结构和力学性能对比，得到 FSW 过程中金属塑性流动行为对接头显微结构和力学性能的影响规律以及作用机理，并建立相关模型，指导生产实践。.本申请有助于揭示FSW接头的成形机理，帮助我们搞清楚FSW过程中BMGs显微结构的变化规律以及高冶金质量焊缝的形成条件，对于推动BMGs的工业化应用进程具有重要的理论和工程价值。

为了解决BMGs制件尺寸小、形状简单的难题，对Zr基大块非晶合金的搅拌摩擦焊连接工艺及其焊接过程中的塑性流变行为进行了研究。结果显示当焊接速度为20 mm/min、搅拌头的旋转速度为400 rpm、下压量为0.1 mm，预热100 ℃时，可以得到表面无缺陷的非晶态焊接接头。通过纳米压痕实验对接头蠕变行为的研究发现非晶态焊接接头由于热输入发生了一定程度的结构弛豫。最后，采用示踪材料法研究了搅拌摩擦焊过程中金属的塑性流动行为，提出了Zr基非晶合金在搅拌摩擦焊过程中的三维塑性流动模型，并采用该模型阐述了搅拌摩擦焊焊接接头的形成过程。这些研究成果将对非晶合金的焊接工艺、接头组织和力学性能的控制提供一定的理论基础，推动非晶合金的工业化应用进程。