**4. Conclusion**

Currently, efforts are being directed towards the development of analytical techniques which rapidly achieve an accurate determination of phase components in an alloy. According to the obtained results, the applicability of the proposed methods provides a practical alternative to other techniques. The phenol extraction procedure was also successfully applied to the examined aluminium alloys. The main advantages of dissolution techniques are its reliability – when used properly you will always get pure residue – and its low price. The major disadvantageous of phenol extraction method are the possible contamination of the residue and the time needed.

The examined alloys AlSi5Cu1Mg and AlCu4Ni2Mg2 possessed a complex microstructure. By using various instruments and techniques (LM, SEM-EDS, TEM and XRD) a wide range of intermetallics phases were identified. The microstructure of investigated AlSi5Cu1Mg alloy included: β-Al5FeSi, α-Al12(FeMn)3Si, Al2Cu, Q-Al5Cu2Mg8Si6, Si and Mg2Si phases. The microstructure of AlCu4Ni2Mg2 alloy included five phases, namely: Al7Cu4Ni, θ′-Al2Cu, Al6Fe, S-Al2CuMg, and Al3(CuFeNi)2. A size and distribution of these various dispersoids depend on the time and temperature of the homogenization and/or annealing processes. Fine intermetallic particles (<lμm) are formed during artificial aging of heat-treatable alloys and are more uniformly distributed than constituent particles or dispersoids. Dimensions, shape and distribution of these particles may have important effects on the ductility of alloys and more needs to be known regarding their formation, structure and composition. For example, the coarse particles can influence the recrystallization, fracture, surface, and corrosion behavior, while the dispersoids control grain size and provide stability to the metallurgical structure. The dispersoids can also affect the fracture performance and may limit strain localization during deformation. The formation of particles drains solute from the matrix and, consequently, changes the strength properties of the material. This is specially relevant in the heat-treatable alloys, where depletion in Cu, Mg, and Si can significantly change the metastable precipitation processes and age hardenability of a material. Therefore, particle characterization is essential not only for choosing the best processing routes, but also for designing optimized alloy composition. Thus, particle characterization is important not only to decide what sort of processing courses should be applied, but also for designing optimized chemical composition of a material. A variety of microscopic techniques are well appropriate to characterize intermetallics but only from a small section of an analyzed sample. From commercial point of view it is extremely advantageous to provide use quick, reliable and economical examination technique capable of providing data of particles from different locations of a full scale-sized ingot. One of these methods is dissolving the matrix of an aluminium alloy chemically or electrochemically.
