ABSTRACT
Defects in crystals, based on their effect on the X-ray diffraction pattern, can be classified as type-I and type-II defects. Type-I defects, like thermal vibrations and vacancies, lead to a decrease in the intensity of the Bragg peaks, without an increase in the peak width. On the other hand, type-II defects like dislocations and stacking faults, result in peak broadening. Dilute solid solutions are type-I defects, which fall into the Huang scattering regime. Concentrated disordered solid solutions, binary or multicomponent, based on their signature on the X-ray diffraction pattern, form a distinct class wherein the disorder permeates the whole solid and is infinitesimal nowhere. On the formation of a concentrated disordered solid solution, the Bragg peaks are broadened, with the existence diffuse intensity between the peaks. Hence, the consequences of the formation of a concentrated alloy on the X-ray diffraction pattern cannot be modelled akin to the effect of temperature. In this chapter we try to comprehend the answer to the following questions, which relate to the effects of the formation of multicomponent disordered solid solutions on the X-ray diffraction pattern. (1) How to compare the Bragg intensity of alloys across a series (as we traverse from pure elements to a multicomponent alloy). (2) Is the intensity decrease significant on the formation of a multicomponent disordered solid solution? (3) Which parameter serves as a good measure of lattice distortion? (4) What is the magnitude of the bond length distortion? (5) How are dilute disordered solid solutions different from concentrated disordered solid solutions?
Key Phrases and Symbols: X-Ray diffraction. diffuse scattering. Lattice strain. Disordered solid solution. Concentrated disordered solid solution. Multicomponent disordered solid solution. Alloy series—starting with a pure element, a series of alloys are created with two, three, four, five (or more) elements. Al–aluminium, Co–cobalt, Cr–chromium, Cu–copper, Fe–iron, Mn–manganese, Ni–nickel, Si–silicon, V–vanadium.
