ASTM E81 Standard Test Method for Preparing Quantitative Pole Figures

ASTM E81 is the standard test method for preparing quantitative pole figures. In this test method, X-ray diffraction is an important non-destructive tool used to study all types of matter ranging from fluids to powders and crystals. X-ray diffraction methods are used to identify crystalline phases in different materials and for quantitative phase analysis. X-ray diffraction methods are better for understanding the three-dimensional atomic structure of crystalline solids. The test method utilizes the Schulz reflection technique. Data for constructing pole figures are obtained with an X-ray diffractometer, using reflection and transmission techniques. Data for making pole figures are obtained with an X-ray diffractometer, using reflection and transmission techniques.

The ASTM E81 test method mentions using the X-ray diffractometer to prepare quantitative pole figures. The test method consists of several experimental procedures. Some of the procedures permit the construction of a complete pole figure. Others must be used in combination to prepare a complete pole figure.

This test method uses an X-ray diffractometer to prepare quantitative pole figures. Ordinarily, in ASTM E81, test specimens are obtained from thicker sections by reducing them mechanically as far as possible, then etching them to the final required thickness. The sample must not be overheated or plastically deformed during thinning.

The ASTM E81 test method characterizes the distribution of orientations of selected lattice planes with respect to sample-fixed coordinates. The distribution is usually obtained by measuring the intensity of X-rays diffracted by the sample. In such measurements, the detector and associated limiting slits are fixed at twice the appropriate Bragg angle, and the diffracted intensity is recorded as the sample orientation changes. After the measured data has been corrected, as necessary, for background, defocusing, and absorption, and is normalized to have an average value of unity, the results may be plotted in stereographic or equal-area projection.

ASTM E81 test method covers the use of the X-ray diffractometer to prepare quantitative pole figures. Pole figures are 2D graphic representations, on polar coordinate paper, of the average distribution of crystallite orientations in 3D. Data for constructing pole figures are obtained with X-ray diffractometers, using reflection and transmission. For an iron sample with molybdenum K-alpha radiation, the linear absorption coefficient is 303 cm⁻¹, and the optimum specimen thickness for transmission is approximately 0.03 mm (0.001 in.). It is extremely difficult to prepare specimens this thin, and in practice, iron specimens having a thickness between 0.05 to 0.1 mm (0.002 to 0.004 in.) are normally used in transmission with molybdenum K-alpha radiation.

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