微纳米金属玻璃的高速加热超塑性成型与力学行为

微纳米金属玻璃在过去十年里受到了人们广泛关注。其新奇力学行为被报导，这些报导因为样品制备和表征手段问题而存在争议。虽然有唯象模型试图解释微纳米金属玻璃的力学行为，但其物理机制和结构起源没有得到很好的解释。项目申请人在这些方面做了一些初步工作。我们将改进之前的微纳米金属玻璃超塑性成型设备，引入电容放电技术，用高速加热法制备高质量多成分体系的微纳米金属玻璃。在此基础上认清微纳米金属玻璃的超塑性成型机理。然后，我们将研制表征微纳米金属玻璃拉伸力学行为和弛豫行为的设备以去除外界因素的影响。我们也将表征拉伸过程中微纳米金属玻璃的结构演变以揭示形变的结构起源。最后，我们将模型化样品中原有自由体积的剪切转变与剪涨区域的剪切转变之间的耦合作用，建立微纳米金属玻璃流变本构方程以揭示其流变与结构演化的关联。本项目将帮助理解微纳米金属玻璃超塑性成型机理与流变的物理起源，为其走向微纳米器件中的应用奠定基础。

Small scale (micro- and nano-scale) metallic glasses (SMG) have attracted extensive attention in the past ten years. Novel mechanical behavior of SMGs has been reported controversially because of preparation and/or testing problems. At the same time, the mechanism and structure origin of such behavior have not been explained either experimentally or theoretically, even though some phenomenon model was proposed. Our previous works have some preliminary results on such issues. Firstly, we will revise our metallic glassy wire preparation equipment to produce high-quality SMGs of various composition systems by introducing capacitor-discharge technique. Based on this, we will unravel the mechanism of superplastic forming of SMGs. Secondly, we will do instrumentation to characterize tensile and relaxation behavior of SMGs without extrinsic effects. Structure evolution during tension will also be investigated to unravel structure origin of mechanical behavior of SMGs. Finally, constitutive equation for depicting deformation of SMGs will be established by modeling coupling of shear transformation at aboriginal free volume and shear dilatation to unravel correlation between deformation behavior and structure evolution of SMGs. The project has implications for understanding fundamentals of superplastic forming and deformation behavior of SMGs and their application in micro- and nano-devices.