文章信息/Info

Title:

Synchrotron Polychromatic X-ray Laue Microdiffraction Study on the Microstructures of Crystalline Materials

作者:

潘志豪; 周光妮; 陳凱

西安交通大學 金屬材料強度國家重點實驗室

Author(s):

PAN Zhihao;  ZHOU Guangni;  CHEN Kai

Center for Advancing Materials Performance from the Nanoscale (CAMP-Nano), State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University

關鍵詞:

白光勞厄微衍射; 晶體結構; 晶體取向; 微觀應變; 缺陷

Keywords:

polychromatic X-ray Laue microdiffraction;  Crystal structure;  Crystal orientation;  Microscopic strain;  Defect

DOI:

10.7502/j.issn.1674-3962.2017.03.03

文獻標志碼:

A

摘要:

伴隨著特種聚焦鏡的出現和同步輻射技術的發展，利用微聚焦的同步輻射多波長X射線進行白光勞厄微衍射成為了可能。通過白光勞厄微衍射實驗，可以對材料局域微觀結構進行無損定量表征，并建立材料的微觀特性與機械性能間的關系。本文以脆性多晶Nd2Ir2O7材料及激光3D打印的鎳基高溫合金材料的為研究案例，體現了同步輻射白光勞厄微衍射技術在研究非均一的多相多晶材料的晶體取向、晶格畸變、缺陷類型和密度等重要微觀結構信息方面的特點與優勢。隨著數據采集和數據分析的飛躍式發展，即使以微小的步長對樣品上一個較大的區域進行勞厄微衍射實驗，也可以近乎實時的獲得晶體材料微觀結構的定量圖像。同步輻射白光勞厄微衍射發展至今已有20年，并且新的同步輻射納米衍射線站正在全世界范圍內建設和服役，這里簡單概括其實驗設施、當前應用、最新技術發展、以及未來可能涉及的領域，并借此激勵越來越多的中國學者利用同步輻射白光勞厄微衍射進行材料科學的研究。

Abstract:

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 (?XRD), and these microstructural features can be further related to the mechanical and physical properties of the crystals. The ?XRD 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, is mapped using the ?XRD technique and related to its 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 ?XRD 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 technical developments, and hopefully can spur more and more Chinese researchers and scientists to take advantage of the powerful ?XRD materials study technique.