Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction
Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction
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DOI：
10.1016/j.nima.2016.06.127
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发表时间：
2016-10-11
影响因子：
1.4
通讯作者：
Suzuki, Hiroshi
中科院分区：
文献类型：
--
作者：
Ikeda, Yoshimasa;Taketani, Atsushi;Suzuki, Hiroshi
基于加速器的紧凑型中子源最近在工程应用方面得到了讨论，如透射式成像、小角散射以及反射率测量。然而，由于它的中子通量很低，没有人考虑将其用于中子衍射实验。因此，本研究利用日本理研加速器驱动的紧凑型中子源(RANS)进行了中子绕射实验，以阐明该紧凑型中子源用于中子工程绕射的能力。通过合理布置光学系统以降低背景噪声，成功地测量了铁素体钢的衍射图，证实了在可接受的测量时间，即10min内，用10 mm立方体的大采样体积就可以测量出可识别的衍射图。在S质子脉冲宽度为8微米时，RANS的最小分辨率约为2.5%，这不足以进行中子衍射应变测量。在110反射对应的波长处的慢化时间宽度估计约为30亩S，这是决定分辨率的最主要因素。因此，通过减小慢化剂的厚度或应用退耦器系统或应用角色散中子衍射技术来改进慢化剂系统以缩短慢化时间，对于提高致密中子源衍射实验的分辨率是重要的。相反，通过RANS测量衍射峰强度的变化，成功地观察到了由塑性变形引起的织构演变。此外，还利用Rietveld程序对衍射图进行了拟合，成功地估算了双相模拟样品中奥氏体相的体积分数。因此，RANS已被证明能够用于中子工程衍射，目的是方便地测量织构和残余奥氏体量。(C)2016年提交人。爱思唯尔出版公司(Elsevier B.V.)
A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 mu s of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 mu s, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access measurement of the texture and the amount of retained austenite. (C) 2016 The Authors. Published by Elsevier B.V.