Brief introduction
Technologies have been used to the analysis of chemical composition, which for the alloy, XRD (X - Ray diffraction analysis) is a kind of very good method. X-Ray diffraction analysis refers to the technique that records the interference of the elastic scattering when X-Ray photons collide with atoms with a periodic structure. [1] XRD could also determine the texture and residual stress in process procedure.
Principle
The λ as the wavelength of the incident ray, d for spacing, θ as the diffraction Angle. XRD tests on the crystal structure is effective. Titanium alloy has a crystal structure. The crystals will have its unique crystallographic characteristics, namely space lattice, 14 Bravais lattice represents the lattice type, crystal parameters and limits on the relative number of relationships between the nodes. Then, refer to the Bragg equation, let X-ray through the crystal, as long as meet the conditions of Bragg diffraction, can provide information on atomic arrangement in crystals.
Limitation
In a strict sense, XRD does not give an intuitive picture of the composition of titanium alloys. But its characteristic peaks and crystal structure can be analyzed to infer the composition of titanium alloy. Because titanium alloys are difficult to liquefy, vaporize, and burn, the techniques used to characterize them are very limited. And it's usually a combination of several techniques to get a more accurate and precise representation. At the same time, XRD does not give the quantity, quality and relative percentage of each component. It only tells you what the material is.
Reference
[1] Chen Yanhui, Northwestern Polytechnical University, X-ray diffraction analysis, May22 2020
[2] Chen Quanzhi, Tang Shiguang, Li Shaobo, Huang Zujiang, Li Weizhou, Zeng Jianmin, High temperature exposure of TC4 titanium alloy micro-arc oxide film, Journal of Materials Protection, 2016, 8th, http://www.mat-pro.com/article/deail.action?article.articleId=26069 2018-5-30
XRD spectrum of annealed TC4
Figure shows the XRD pattern of oxidation film prepared from a titanium alloy matrix and three main salts. It can be known that the phases of oxide films prepared in the three solutions all contain Al2TiO5, rutile phase (R-TiO2), α-Al2O3, and the alloy matrix contains Ti (α-Ti and β-Ti), Al, V(TiV and AlV). From the horizontal axis can get their diffraction angle θ.