Tham khảo tài liệu 'asm metals handbook - desk edition (asm_ 1998) episode 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fig. 4 Planes in three-dimensional crystals defined by their Miller indices. Source Ref 2 In simple crystal structures . cubic planes with various combinations and permutations of the same indices have identical interplanar spacings. These spacings are referred to as types of planes. For example in a cubic crystal 112 121 211 -112 -211 etc. all spacings are referred to as planes of the type 112 . A number of different types of information can be determined from XRD experiments. The primary types of analyses and their uses are described in the following sections along with information about the threshold sensitivity and precision limitations sample requirements and capabilities of related techniques. References cited in this section 1. R. Jenkins and R. Snyder Introduction to X-Ray Powder Diffractometry John Wiley 1996 2. C. Barrett and T. Massalski Structure of Metals McGraw-Hill 1966 Identification of Compounds and Phases Using X-Ray Powder Diffraction Typical Uses X-ray powder diffraction is used to identify the crystalline phases present in a sample. Examples of the types of questions that can be answered using x-ray powder diffraction include Is a heat treated steel sample 100 martensite or does it contain some retained austenite What compounds are present in the corrosion product that formed when an aluminum alloy was exposed to sea spray What compounds are present in the scale formed on a ingot during high-temperature forging Solving these types of problems by x-ray powder diffraction is the most common use of XRD in metallurgy. Experimental Approach In x-ray powder diffraction an x-ray beam of a single known wavelength is used to determine the interplanar spacings of the planes in the sample. The sample is typical polycrystalline ideally containing a semi-infinite number of randomly oriented crystals. Bragg s law dictates that each set of crystal planes will diffract at its own characteristic angle. Once these angles at which diffraction occurs have been
