依托扫描电镜发展的原位力学实验技术，集成了扫描电镜的高分辨率成像优势，可以在对材料表面形貌变化细节进行观测的同时获得材料变形本构关系，这对研究微纳米材料的灾变、破坏等非线性力学行为具有重要的意义。其中，原位微尺度扭转实验技术可以创造剪切应力环境，对金属玻璃流变机制、仿生结构材料设计以及柔性电子器件力学性能等问题的研究具有重要价值。

    本文旨在研发一种基于电磁驱动原理的扫描电镜原位微扭转测试仪，发展扫描电镜原位微尺度扭转实验技术，解决微尺度材料在电镜下原位扭转力学性能测试的难题。

    本文的工作包括原位微扭转测试仪的研制、标定和应用三部分。测试仪的研制包括：对技术指标的确定、仪器主机设计制作、控制器与软件系统搭建以及仪器的力学模型分析。主要的技术路线是，基于电磁驱动原理实现扭矩的加载与测量，由非接触式传感器测量扭转角度。解决了为适应SEM环境要求而带来的卧式工作方式、磁场屏蔽、仪器微型化等关键技术难题。对仪器、试样、SEM工作环境耦合的动力学响应模型进行分析，据此发展了针对该仪器的标定和检验方法，完成了仪器的标定与检验工作。主要包括：扭矩相关标定、角度相关标定、系统相关标定。基于电子天平扭矩校准技术实现了对扭矩相关参数的标定。研制完成的原位微扭转测试仪主要技术指标为：扭矩量程为1.4×10^-4 N·m，分辨率1.5×10^-9 N·m，噪声水平约为4×10^-8 N·m，角度量程为100°，分辨率0.006°，噪声约为0.06°。

    最后，选用了直径约50mm的钨丝与直径约110mm的钯基非晶合金丝(Pd₄₀Cu₃₀Ni₁₀P₂₀)作为典型材料，在SEM中进行原位扭转实验，获得了材料的扭转本构曲线，实现了扭转性能测试与显微形貌观测的同步进行，检验了仪器的性能。同时，非晶合金丝剪切模量测试结果与文献参考值接近，证明了本文研制仪器的可靠性。

The in-situ mechanical experiment technology developed based on Scanning Electron Microscopy (SEM), with the advantages of high resolution imaging, can obtain the deformation morphology details combining the constitutive relation of materials, which is of great significance for the study of nonlinear mechanical behaviors such as fracture of micro/nano materials. Among them, the in-situ micro- torsion experiment technology can create a shear stress environment, which is of great value for the study of the shear rheological mechanism of amorphous alloy wires, the design of bionic structural materials and the mechanical properties of flexible electronic devices, etc.

The purpose of this paper is to develop an in-situ SEM micro-torsion tester based on electromagnetism, study the corresponding experiment technology to solve the problems of in-situ SEM torsion testing for micro-scale materials.

The work of this paper includes three parts: development, calibration and application of in-situ micro-torsion tester. The development of the tester includes: the determination of technical indexes, the design and manufacture of the tester, the making of controller and software system, and the analysis of the mechanical model of the instrument. The technical routes are: load and measure the torque by electromagnetic principle, and measure the torsion angle by non-contact angle senor. The key technical problems caused by SEM environment, such as horizontal working mode, magnetic field shielding and instrument miniaturization, are solved. The coupling dynamic mechanical model of the tester, sample and SEM working environment is analyzed. Corresponding, the calibration method for the tester is developed, and the calibration works are performed. Included the calibration of torque, angle and system. The calibration works of torque parameters were finished based on the electronic balance torque calibration technology. The main technical indexes of the in-situ SEM micro-torsion tester are: the torque range is 1.4×10^-4 N·m with the resolution of 1.5×10^-9 N·m and noise of 4×10^-8 N·m; The angle range is 100 Deg with the resolution of 0.006 Deg and noise of 0.06 Deg.

Finally, the in-situ SEM micro-torsion test of tungsten wire with a diameter of 50mm and amorphous alloy wire (Pd₄₀Cu₃₀Ni₁₀P₂₀) with a diameter of 110mm are carried out. The torsional deformation constitutive curves of materials are obtained. It was implemented that measurement of torsion test and morphology observation are carried out simultaneously, which meet the expected the performance of the tester. At the same time, the test results of shear modulus of amorphous alloy wires are close to the reference values, which proves the reliability of the tester developed in this paper.