材料期刊网

伴随着特种聚焦镜的出现和同步辐射技术的发展,利用微聚焦的同步辐射多波长X射线进行白光劳厄微衍射成为可能.通过白光劳厄微衍射实验,可以对材料局域微观结构进行无损定量表征,并建立材料的微观特性与机械性能之间的关系.脆性多晶Nd2Ir2O7材料及激光3D打印的镍基高温合金材料的研究,体现了同步辐射白光劳厄微衍射技术在研究非均一的多相多晶材料的晶体取向、晶格畸变、缺陷类型和密度等重要微观结构信息方面的特点与优势.随着数据采集和数据分析的飞跃式发展,即使以微小的步长对样品上一个较大的区域进行劳厄微衍射实验,也可以近乎实时的获得晶体材料微观结构的定量图像.同步辐射白光劳厄微衍射发展至今已有20多年,并且新的同步辐射纳米衍射线站正在全世界范围内建设和服役.简单概括了同步辐射白光劳厄微衍射其实验设施、当前应用、最新技术发展以及未来可能涉及的领域,并借此激励更多的中国学者利用同步辐射白光劳厄微衍射技术进行材料科学的研究.

With the advent of efficient brightness-preserving X-ray focusing optics and synchrotron radiation-based techniques,local crystal structure,orientation,microscopic elastic strain/stress,and defect type and density can all be probed with a single scan of micro-focused synchrotron polychromatic X-ray Laue diffraction (μXRD),and these microstructural features can be further related to the mechanical and physical properties of the crystals.The μXRD technique is particularly suitable for the non-destructive and quantitative mapping of the microstructural characteristics of inhomogeneous multiphase polycrystalline samples,as well as imperfect epitaxial crystals,without involving any critical sample preparation procedures.In this paper,three examples are introduced in details.First of all,the orientation distribution Nd2Ir2O7 polycrystals,which are brittle and virtually impossible for fine surface polishing,are mapped using the μXRD technique and related to their unique electrical conductance distribution.Secondly,the elastic lattice strain distribution in laser 3D printed Ni-based superalloy is studied and compared to the case in cast bulk materials.Finally,the defect type (mainly dislocations) and density are thoroughly mapped from the matrix to the cladding layers of a laser 3D printed Ni-based superalloy.By studying the nano-hardness of the same region using the technique of nano-indentation,the mechanical properties are successfully linked with the dislocation densities.As μXRD enters its 20th year of existence and new synchrotron nanodiffraction facilities are being built and commissioned around the world,two dimensional or even three dimensional scans on the testing specimens with tiny scanning steps become possible and giant amount of Laue diffraction data are collected.Therefore new data analysis algorithms and tools are being developed.In this paper we briefly review the new achievements and trends in this field.We take the opportunity to overview the current capabilities as well as the latest techinical developments,and hopefully can spur more and more Chinese researchers and scientists to take advantage of the powerful μXRD materials study technique.