Zr基块体非晶合金过冷液相区超塑性微成形流变机理研究

The application of bulk metallic glasses as engineering materials is restricted due to poor room temperature processing performance. Developing micro-forming technology of metallic glasses is an effective way to solve the problem. However, the fundamental questions such as the temperature-time window of supercooled liquid stabilizing without phase change, the influence factors and the changing rules of viscosity, the scale effect during micro forming of metallic glasses are unsolved, which become the main bottlenecks restricting the popularization and application of the micro-forming technology. In this application, intending to Zr-Cu-Al-Ni-Re bulk metallic glasses as the research object, basic scientific research on rheological mechanism of superplastic micro-forming for Zr-based metallic glasses in the supercooled liquid region are proposed to conduct. The concrete contents are as follows. Zr-based bulk metallic glasses suitable for micro-forming will be optimized and prepared, and the temperature-time relationship of supercooled liquid stabilizing without phase change will be determined. Using the thermal simulation experiment，the influence factors and the changing rules of viscosity shall be systematically studied. Micro-nano scale moulds with the same cavity and different size will be designed, and the scale effect during micro-forming will be systematically studied. The micro-nano scale thermal processing map of micro-forming will be established, and the rheological mechanism of superplastic micro-forming of Zr-based bulk metallic glasses will be revealed. This subject has important theortical guiding significance on perfecting the fundamental research of the micro-forming technology for metallic glasses, and promoting the application in the micro-forming technology.

块体非晶合金由于室温加工性能差而严重制约着其作为工程材料的应用，开发块体非晶合金微成形技术是解决该问题的有效途径。然而，非晶合金过冷液态稳定而不发生相变的温度-时间窗口、粘度的影响因素和变化规律及微成形中的尺度效应等基础问题尚未解决，成为制约该项技术推广应用的主要瓶颈。本申请以Zr-Cu-Al-Ni-Re块体非晶合金为对象，对其过冷液相区的超塑性微成形流变机理进行基础科学研究。具体内容包括：优化制备出适合于超塑性成形的Zr基块体非晶合金，确定其过冷液态稳定而不发生相变的温度-时间关系；利用热模拟实验，系统研究过冷液态粘度的影响因素及变化规律；设计型腔相同、尺寸大小不同的微纳尺度模具，系统研究超塑性微成形过程中的尺度效应，建立微纳尺度微成形热加工图，揭示Zr基块体非晶合金超塑性微成形流变机理。本课题对于完善块体非晶合金微成形技术的基础研究，拓展其在微成形技术领域的应用具有重要的理论指导意义。

随着高新技术的迅猛发展，产品微型化是工业发展的重要趋势。非晶合金由于不存在晶粒尺度效应，具有极小的热膨胀系数和良好的近净成形能力，因此被誉为微成形技术的理想材料，从而应用于微机电系统(Micro-electro-mechanical system, MEMS)，在IT产业、生物医疗、武器装备、航空、航天等领域有广阔的应用前景。然而非晶合金在过冷液相区保持稳定而不发生相变的温度-时间窗口、粘度的影响因素和变化规律及微成形过程的流变行为尺度效应是非晶合金应用于微成形技术中急需解决的关键基础问题。.本研究通过非晶合金的成分优化制备、相关力学性能实验、XRD和TEM结构分析、热模拟实验和成形过程的流动性模拟以及热加工图的构建对非晶合金过冷液态稳定而不发生相变的温度-时间窗口、粘度的影响因素和变化规律及微成形过程的流变行为尺度效应等三个基础科学问题进行系统研究。主要研究内容和结论为：(1)从成分设计出发，通过室温力学性能的测定，优化制备出了系列适合于超塑性成形的Zr基块体非晶合金，确定了过冷液相区过冷液态稳定而不发生相变的温度-时间关系，为Zr基块体非晶合金用于超塑性微成形技术的成分选择提供了理论支撑。(2)系统研究了Zr基块体非晶合金过冷液相区过冷液态粘度的影响因素，确定了流动应力、应变速率、温度、粘度之间的关系，揭示了粘度的变化规律，为超塑性微成形时参数的选择提供理论依据。(3)研究了Zr基块体非晶合金超塑性微成形过程中的尺度效应，构建了超塑性微成形热加工图，揭示了超塑性微成形流变机理，为Zr基块体非晶合金在过冷液相区微成形时加工工艺的选择提供了理论指导。.研究成果为适合于超塑性成形的Zr基块体非晶合金的成分设计提供理论依据；为深入研究Zr基块体非晶合金过冷液相区超塑性微成形流变机理并优化微成形工艺提供了理论指导；为推广Zr基块体非晶合金在微机电系统的应用奠定了坚实的理论基础和应用指导。