硬X射线微探针热台装置、实验方法及其在镍合金高通量表征方面的应用

Facing the high-throughput research needs of the "composition-structure-temperature-time" correlation of materials, and in view of the problems in the existing heating stages including X-ray transmittance, sample rotation-centering, temperature calibration, back scattering fluorescence detection etc., a set of vertical heating stage device with high transmittance for high temperature and high throughput characterization is developed by innovating and optimizing the design of window, mechanical layout, new efficient heater and heat shield, vacuum sealing, sample holder and effective finite element thermal analysis. The corresponding experimental method is also developed for the simultaneous data collection of high temperature back scattered fluorescence and transmitted diffraction mapping after sample rotation-centering with high-precision. The device and its experimental method which can make full use of the advantages of high brightness, high spatial resolution and high detection sensitivity of synchrotron radiation hard X-ray microprobe, is applied to characterize the composition transition zones of diffusion-multiple directly at high temperatures in high throughput mode，obtain the change of Y ultra-low solid solubility in nickel alloys with temperature, measure the growing and dissolution dynamics parameters of carbides in the nickel alloys, and analyze of the diffusion mechanism of the alloying elements and the formation conditions of the deleterious phases of intermetallic compounds. Finally, the above results of characterization are used to guide the research and development of Y+Ti modified Ni-16Mo-7Cr-5Fe-C alloys, in order to improve the service performance of the alloys in the molten salt reactor and testify the application effect of the heating stage.

面向材料“成分-结构-温度-时间”相关性高通量研究需求，针对现有热台在透光率、样品对中、温度校准和背散荧光探测等方面存在的问题，通过窗口、机械布局、真空密封、新型高效加热器及其热屏蔽、样品舱等的创新和优化设计以及有限元热分析来研制一套立式高透光率高温热台表征装置，并发展集成高精度样品对中技术的高温背散荧光和透射衍射并行同步面扫采谱方法。该装置及其实验方法能够高效发挥同步辐射硬X射线微探针高亮度、高空间分辨和高探测灵敏度的优势，被应用于高温下直接高通量快速表征扩散偶和扩散节的成分过渡区，获取镍合金中Y超低固溶度随温度的变化情况和测量镍合金中碳化物长大和溶解动力学参数，并分析元素的扩散机制及金属间化合物有害相的生成条件。最后，用上述表征结果指引Y+Ti改性Ni-16Mo-7Cr-5Fe-C合金的研发，以全面地提高Ni-16Mo-7Cr-5Fe-C合金的熔盐堆服役性能和验证热台装置的应用效果。

面向材料“成分-结构-温度-时间”相关性高通量研究需求，针对现有热台在透光率、样品对中、温度校准和背散荧光探测等方面存在的问题，通过窗口、机械布局、真空密封、新型高效加热器及其热屏蔽、样品舱等的创新和优化设计研制了一套工作温度高达1400℃的立式高透光率高温热台表征装置，并发展了集成高精度样品对中技术的高温背散荧光和透射衍射并行同步面扫采谱方法。该方法实现了微束荧光和衍射数据同步采集，且集成了吸收谱学技术，因而保证了多方法测试的时空一致性。该方法能够高效发挥同步辐射硬X射线微探针高亮度、高空间分辨和高探测灵敏度的优势，被应用于高通量快速表征扩散偶和扩散节的成分过渡区。进一步地，在国内首次发展了自动定位零角度的硬X射线微束高通量掠入射表征实验方法，并将此具有微米级高空间分辨率的方法应用于纳米厚度薄膜的微区分析。零角度自动化定位的扫描结果表明，实验系统微区分析的空间分辨率达到2.8μm，零角度定位精度小于±0.01°。在不同掠入射角下测量了薄膜样品的衍射信号，获取不同入射深度下样品的衍射峰强度，并实现在同一掠入射角下，同步采集样品的荧光计数信号，从而确定了样品表层的相结构信息以及荧光信号强度与入射角关系，实现了对纳米厚度薄膜在微小区域的相结构和组分同时分析。此外，通过该技术能够选取荧光计数最大值对应的入射角度，有助于提高后续发展的低浓度样品掠入射X射线吸收近边结构实验方法的信噪比。该实验方法对分析样品表面或薄膜在微小区域的不均匀组分、结构、厚度、粗糙度和表面元素化学价态等信息具有重要意义。