LATTICE IMPERFECTION STUDIES IN POLYCRYSTALLINE MATERIALS BY X-RAY-DIFFRACTION LINE-PROFILE ANALYSIS
LATTICE IMPERFECTION STUDIES IN POLYCRYSTALLINE MATERIALS BY X-RAY-DIFFRACTION LINE-PROFILE ANALYSIS
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DOI：
10.1007/bf02894766
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
SENGUPTA, SP
中科院分区：
文献类型：
--
作者：
DE, M;SENGUPTA, SP
本文综述了我们最近对一系列面心立方银和铜基合金(Vizag-Ga，Ag-Ge，Ag-Al和Cu-Ga，Cu-Ge)的X射线衍射线分布的详细分析，并对其重要性进行了简要的总结。概述了Warren-AVerbach峰形傅里叶分析方法以及峰位移法和峰不对称法的理论公式。简要介绍了早先在银基和铜基(Fcc)二元合金方面所进行的重要研究。对本研究中记录的剖面的详细分析表明，一般而言，对表征材料变形状态的几个微观结构参数进行了定量估计，即：层错倾向(本征、本征和孪生断层)、均方根微应变、相干域尺寸、长程残余应力、晶格参数变化、位错密度和层错能。结果表明，随着溶质浓度的增加，层错的浓度总体上呈增加的趋势，主要是本征的，这是观察到的峰移动和磁区尺寸加宽的唯一原因。剖面上小的不对称性是由于存在外在的堆积断层，与本征的堆积断层相比，其强度相对较小，而形变孪生断层几乎不存在--这是一个有意义的观察结果。位错密度的大小相当可观，已经从相干域尺寸和均方根微应变的各向异性值中估计出来。我们还估算了一个重要参数--纯银和纯铜的层错能，并与电子显微镜的结果进行了比较。用以铝为沉淀溶质的Ag-5.8%Al合金进行的退火实验，没有发现任何可检测到的溶质在层错处偏析的证据。合金体系中层错的发生与涉及溶剂-溶质类型的许多物理因素有关。
This review concerns our recent investigations with a series of binary fcc Ag- and Cu-base alloys (vizAg-Ga, Ag-Ge, Ag-Al and Cu-Ga, Cu-Ge) from detailed analyses of x-ray diffraction line profiles, the importance of which has been briefly summarized. The theoretical formulations of the Warren-Averbach’s method of Fourier analysis of peak-shapes along with the methods of peak-shift and peak-asymmetry have been outlined. A preview on the significant studies carried out earlier with Ag- and Cu-base (fcc) binary alloys has been made in short. A detailed analyses on the recorded profiles in the present considerations revealed, in general, quantitative estimates of several microstructural parameters characterising the deformed state of the materials namely, propensity of stacking faults (intrinsic, extrinsic and twin faults), rms microstrains, coherent domain sizes, long-range residual stresses, lattice parameter changes, dislocation density and stacking fault energy. The results indicate a general trend of increase in the concentrations of stacking faults, primarily, of intrinsic character, with increase in solute concentrations; which are solely responsible for the observed peak-shifts as well as domain size broadening. Small asymmetry in the profiles is due to the presence of extrinsic stacking faults, relatively less in magnitude compared to the intrinsic ones while the deformation twin faults are almost absent—an observation with significance. The dislocation density, quite appreciable in magnitude, has been evaluated from the anisotropic values of the coherent domain sizes and rms microstrains. The stacking fault energies of pure Ag and Cu, an important parameter have also been estimated and compared with those obtained from electron microscopy. Annealing experiments with a Ag-5·8% Al alloy, aluminium being a precipitating solute, do not reveal any detectable evidence of solute segregation at the stacking faults. The occurrence of stacking faults in the alloy systems has been correlated with a number of physical factors involving solvent-solute types.