Microstrain and grain-size analysis from diffraction peak width and graphical derivation of high-pressure thermomechanics
Microstrain and grain-size analysis from diffraction peak width and graphical derivation of high-pressure thermomechanics
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DOI：
10.1107/s0021889808031762
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发表时间：
2008-12-01
影响因子：
6.1
通讯作者：
Zhang, Jianzhong
中科院分区：
文献类型：
--
作者：
Zhao, Yusheng;Zhang, Jianzhong
提出了一种分析方法，用于推导多晶材料在高压 (P) 和高温 (T) 条件下的热机械性能。该方法通过检查不同 P-T 条件下的峰宽变化来处理异质晶粒之间的不均匀应力和纳米晶材料的表面应变。由于该方法直接处理晶格 d 间距和由应力引起的局部变形，因此它可以应用于处理任何衍射剖面，而与检测模式无关。此外，还开发了一种使用衍射弹性比来处理与纳米级晶粒尺寸相关的严重表面应变和/或应变各向异性效应的校正程序，以便可以以物理上有意义的方式减少显着的数据散射。所得微应变分析的图形说明可以识别由高应力集中引起的晶粒间相互作用的微观/局部屈服，以及整个样品塑性变形的宏观/整体屈服。这种简单直接的方法能够揭示相应的微观和/或宏观屈服应力、晶粒破碎或生长、加工硬化或软化、高 P-T 条件下的热松弛，以及多晶块中的固有残余应变和/或表面应变。此外，这种方法允许以直接的方式说明和减去仪器的贡献，从而避免仪器校正带来的潜在复杂性和错误。通过同步加速器 X 射线和飞行时间中子衍射对 α-SiC（6H，碳硅石）和微晶和纳米晶镍的研究证明了该方法的应用。
An analytical method is presented for deriving the thermomechanical properties of polycrystalline materials under high-pressure (P) and high-temperature (T) conditions. This method deals with non-uniform stress among heterogeneous crystal grains and surface strain in nanocrystalline materials by examining peak-width variation under different P-T conditions. Because the method deals directly with lattice d spacing and local deformation caused by stress, it can be applied to process any diffraction profile, independent of detection mode. In addition, a correction routine is developed using diffraction elastic ratios to deal with severe surface strain and/or strain anisotropy effects related to nano-scale grain sizes, so that significant data scatter can be reduced in a physically meaningful way. Graphical illustration of the resultant microstrain analysis can identify micro/local yields at the grain-to-grain interactions resulting from high stress concentration, and macro/bulk yield of the plastic deformation over the entire sample. This simple and straightforward approach is capable of revealing the corresponding micro and/or macro yield stresses, grain crushing or growth, work hardening or softening, and thermal relaxation under high-P-T conditions, as well as the intrinsic residual strain and/or surface strain in the polycrystalline bulk. In addition, this approach allows the instrumental contribution to be illustrated and subtracted in a straightforward manner, thus avoiding the potential complexities and errors resulting from instrument correction. Applications of the method are demonstrated by studies of alpha-SiC (6H, moissanite) and of micro- and nanocrystalline nickel by synchrotron X-ray and time-of-flight neutron diffraction.