## 1 Introduction  
The development of technology places high demands on construction materials. More and more construction materials are being created, and the materials used are gaining increasingly higher mechanical properties. Achieving mechanical properties with higher parameters requires research to be conducted. In the case of classical construction materials, their chemical composition has already been largely optimized. Their further development can be achieved by influencing technological processes. These processes allow for the shaping of the microstructure of alloys and, consequently, the mechanical properties of the alloys [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11]. Hypoeutic silumins have been widely used in industry. This is due to their good corrosion resistance, good mechanical and physical properties and low melting point. Unfortunately, despite the large number of advantages, they have a rather troublesome disadvantage, which is the tendency to create a microstructure with large dimensions of individual phases. Large eutectic silicon platelets constitute the natural notches of the microstructure. They are the reason for the low mechanical properties of alloys. For many years, a number of technological procedures have been known to refine the microstructure and, at the same time, increase the mechanical properties resulting from the microstructure [12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. Hypoeutic silumins are one of the few alloys in which, as a result of changes in the microstructure, it is possible to increase all mechanical properties, e.g., tensile strength and elongation, at the same time. In most metal alloys, as one parameter increases, the other decreases. Many technological processes are known that allow for the modification of the microstructure. The literature provides the results of research leading to an increase in the properties of silumins, using temperature gradients [23], electromagnetic fields, heat treatments [24, 25], chemical modifications [26, 27, 28, 29, 30], etc. Chemical modification and heat treatment have been widely used in industrial practice. The process of the chemical modification of hypoeutectic sliumins was described in 1921 [41]. Since then, a lot of works have been written showing the influence of various elements, chemical compounds [42, 43, 44, 45] and the technological processes [46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57] on the microstructure and mechanical properties of the tested sliumins. Unfortunately, despite such a significant amount of research, it has not been possible to clearly identify the mechanisms causing microstructure refinement and increases in mechanical properties. A number of hypotheses have described the mechanisms of modification. Based on a literature analysis, it can be assumed that there are many modification mechanisms. Taking into account the large number of published results and the constant lack of a clear and reliable modification mechanism, it can be assumed that, at the current level of technique, this is a very complex issue, and is very difficult or even impossible to explain [26, 27, 28, 29, 50, 51, 52, 53, 54, 55, 56, 57]. Most likely, for this reason, many authors of research papers present research results without even trying to create further theories of the probability of the chemical modification process of alloys. Works have been found in the literature describing the influence of master alloys containing aluminum, titanium and boron on the microstructure and properties of hypoeutectic sliumins [58, 59]. Some authors have conducted research with different proportions of titanium and boron in the master alloy [59, 60, 61, 62]. In many studies, the authors modify hypoeutectic slium by introducing titanium and boron into the liquid alloy in the form of a powder or rod. There are works presenting the results of silumin modification using the available industrial alloy, AlTi5B1 [58]. There are works in which the authors define the titanium-to-boron ratio of 5:1 as optimal [63, 64].