## 2 Materials and Methods
### Procedure for Manufacturing AMCs  
Figure 1 shows the stages of the AMC's fabrication process carried out in the melting area of 540 \(\times\) 580 mm\({}^{2}\) of the Department of Technological Machines and Transportation of Karaganda Industrial University at 24.4-28.1 \({}^{\circ}\)C and at the air humidity of 60-74%. The electric resistance furnace used to prepare the composites had a power of 5 kW, a maximum temperature of 1200 \({}^{\circ}\)C, and a temperature accuracy of \(\pm\)1 \({}^{\circ}\)C. During the experimental procedure, the electric resistance furnace was turned on and heated to 750 \({}^{\circ}\)C. Then, pre-heated blocks of pure aluminum with a crucible were placed in the heating chamber of the electric resistance furnace to melt the aluminum materials. For mechanical stirring, a cantilever electric stirrer had a speed range of (50-2200) \(\pm\) 3 rpm, power of 70 W, and a steel impeller with four blades with angles of 90\({}^{\circ}\). The diameter of the impeller with blades was half the diameter of the crucible (42 mm). The stirrer motor was insulated from below and on the sides with refractory mullite-silica wool (kaolinite wool) to avoid undesirable heating. The heating chamber of the resistance furnace and the sides of the crucible had additional insulation with the same material to limit heat loss. Mechanical stirring was performed at 600 \(\pm\) 3 rpm with vortexing for approximately 7-10 min. The pre-weighed and heated B\({}_{4}\)C particles and K\({}_{2}\)TiF\({}_{6}\) wetting agent were introduced gradually into the formed molten metal vortex using a stainless-steel spoon. The temperature was monitored using a K-type chromel-alumel thermocouple. The stirrer impeller slowly moved at a height above and below the mid-height of the melt because the mechanical stirrer can make a reciprocating motion on the cantilever to intensify melt mixing. After mechanical stirring to remove slag from the melt surface, ultrasonic treatment or cavitation occurred using the ultrasonic system JH-LRT30 (Hangzhou Precision Machinery Co., Ltd., Hangzhou, China), which has an ultrasonic probe with a titanium alloy head, transducer, or converter connected to a powerful ultrasonic generator (Figure 1). Ultrasonic stirring occurred at 20.53-20.62 kHz and a power of 2 kW for 20 min, creating high-intensity ultrasonic waves and vibrations [29; 30]. After ultrasonic stirring, the melt was cast into a steel mold to obtain cast AMC specimens as round rods with dimensions of \(\mathcal{O}\)25 mm \(\times\)220 mm. To remove all possible moisture, the casting mold was preheated with a blowtorch and then in the muffle furnace to a temperature of 300 \({}^{\circ}\)C (together with a refractory fieclay brick on the upper surface of which the casting mold stood during casting) and maintained at this temperature to minimize directional solidification and heat transfer in the casting process. The steel clamps held the mold at both ends during the composite casting process. Experimental observations revealed that it takes approximately 3-3.5 h for the mold to cool down to room temperature. Thus, specimens S1 and S2 were obtained for further characterization. After cooling, some specimens were subjected to T6 heat treatment [25] to obtain S1-HT and S2-HT. Solid solution heat treatment of the specimens was performed in a muffle furnace at 520 \({}^{\circ}\)C for two hours, followed by water quenching. For artificial aging, the specimens were heated to 180 \({}^{\circ}\)C, maintained at that temperature for 12 h, and then cooled in air. After complete cooling, the AMCs were mechanically wet-cut into individual pieces and then used to assess and analyze the specimen characteristics. Initially, all external shrinkages of the specimens were wet-cut on a lathe with a continuous supply of water coolant emulsion to the cutting zone. Dog-bone-shaped specimens were also prepared using this method for uniaxial tensile testing according to ASTM E8 recommendations [31].