XRD精修解析Fe-RE系晶格常数、微应变与位错密度特征

XRD Refined Analysis of Fe-RE System Lattice Constant,Micro Strain and Dislocation Density Characteristics

采用Rigaku MiniFlex 600X射线衍射仪进行物相鉴定和晶格分析,利用Rietveld结构精修理论计算解析了Fe-RE系晶格常数、微应变与位错密度特征。采用峰形函数和最小二乘法得到实验钢精确的拟合图谱,并通过与晶体的初始结构模型比较,从晶体学角度解释稀土的添加对铁多晶体微观结构的影响。结果表明,由于稀土原子半径比铁原子半径大,稀土固溶在铁基中后,部分稀土原子进入铁基固溶体,使得钢的晶格常数有变大的趋势,晶格密度变小;以空位机制扩散后占据空位等缺陷而引起晶格畸变,使得钢中微应变增大;同时,占据位错处的稀土原子会阻碍位错运动,使得钢在加工变形中位错密度增加。

The Rigaku MiniFlex 600 X-ray diffractometer was used for phase identification and lattice analysis,and the Rietveld structure refinement theory was used to calculate and analyze the characteristics of the Fe-RE system lattice constant,microstrain,and dislocation density.The peak shape function and the least square method are used to obtain the accurate fitting pattern of the experimental steel,and by comparing it with the initial structure model of the crystal,the influence of the addition of rare earth on the microstructure of the iron polycrystal is explained from the crystallographic point of view.The results show that after the rare earth is solid-dissolved in the iron base,because the radius of the rare earth atom is larger than that of the iron atom,part of the rare earth atoms enters the iron-based solid solution,which makes the lattice constant of the steel tend to become larger and the lattice density become smaller;After the mechanism diffuses,defects such as vacancies are caused to cause lattice distortion,which increases the micro-strain in the steel.At the same time,the rare earth atoms occupying the dislocations will hinder the movement of the dislocations,which will increase the dislocation density in the processing deformation of the steel.