Acta Metall Sin  2020, Vol. 56 Issue (4): 487-493    DOI: 10.11900/0412.1961.2020.00016
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A Method to Calculate the Dislocation Density of a TWIP Steel Based on Neutron Diffraction and Synchrotron X-Ray Diffraction
LI Yizhuang1,2,HUANG Mingxin1,2()
1.Department of Mechanical Engineering, The University of Hong Kong, Hong Kong 999077, China
2.Shenzhen Institute of Research and Innovation, The University of Hong Kong, Shenzhen 518057, China
Abstract

The modified Williamson-Hall method, which has been widely used to calculate dislocation densities of high-strength steels and other structural alloys, is re-examined in this work, and is further applied to calculate the dislocation density of a deformed twinning-induced plasticity (TWIP) steel by using its neutron diffraction patterns and synchrotron X-ray diffraction patterns. This paper aims not only to promote the proper use of the method but also to shed light on its underlying pre-requisites and assumptions, and is thus expected to help avoid any errors during its usage.

 ZTFLH: TG115，TG142
Fund: National Key Research and Development Program of China(2019YFA0209900);National Natural Science Foundation of China(U1764252);Research Grants Council of Hong Kong(17255016);Research Grants Council of Hong Kong(17210418);Research Grants Council of Hong Kong(R7066-18)
Corresponding Authors:  Mingxin HUANG     E-mail:  mxhuang@hku.hk
 Fig.1  Synchrotron XRD patterns (blue) and neutron diffraction patterns (red) of the undeformed and deformed twinning-induced plasticity (TWIP) steel (K is the reciprocal of the lattice spacing)Color online Fig.2  The relationship between ΔK and K of the undeformed TWIP steel and the standard sample (ΔK is the full width at half maximum (FWHM) of the corresponding diffraction peak at K)Color online Fig.3  The relationships between ΔK (corrected) and K of the deformed TWIP steel measured by neutron diffraction and synchrotron XRD Fig.4  The modified Williamson-Hall plots obtained by neutron diffraction and synchrotron XRD (β=(1.5φs+φt)/a, where a is the lattice constant; φs and φt are the probability of finding a stacking fault and a twin boundary in {111} planes, respectively; Whkl is a factor to scale the faulting-induced peak broadening at different {hkl} reflections; $Cˉ$ is the average dislocation contrast factor)