The study involved measurements of surface tension of liquid binary copper-bismuth alloys with respect to their chemical composition and temperature as well as investigations of the liquid alloy - refractory material - gaseous phase system wettability using usual refractory materials, i.e. aluminium oxide, magnesium oxide and graphite. The experiments were performed with the use of sessile drop method and a high-temperature microscope coupled with a camera and a computer was utilised.

Autogenous laser welding of 0.8 mm thick butt joints of car body electro-galvanized steel sheet DC04 was investigated. The Yb:YAG disk laser TruDisk 3302 with the beam spot diameter of 200 μm was used. The effect of laser welding parameters and technological conditions on weld shape, penetration depth, process stability, microstructure and mechanical performance was determined. It was found that the laser beam spot focused on the top surface of a butt joint tends to pass through the gap, especially in the low range of heat input and high welding speed. All test welds were welded at a keyhole mode, and the weld metal was free of porosity. Thus, the keyhole laser welding of zinc coated steel sheets in butt configuration provides excellent conditions to escape for zinc vapours, with no risk of porosity. Microstructure, microhardness and mechanical performance of the butt joints depend on laser welding conditions thus cooling rate and cooling times. The shortest cooling time t8/5 was calculated for 0.29 s.

In the paper, results of surface tension measurements with regard to liquid copper-silver alloys with the maximum silver content of 40 % mass Ag are presented. The measurements were performed at 1373-1573 K with the use of the sessile drop method. In the study, a high-temperature microscope, coupled with a camera and a computer equipped with the software designed for experiment recording and picture analysing, was applied. In order to determine surface tension values, the least square estimation of the parameters of the system of differential equations, describing the shape of a liquid sessile drop, was used.

Increasing the share of circulating scrap in produced castings is not only due to optimizing production costs, but also the need to protect the environment realized by reducing production energy intensity, generating less waste, mitigating greenhouse gas emissions, and consuming fewer natural resources. However, this is associated with maintaining the required properties of castings and considering the impact of impurities on the formation of the structure of aluminum alloys. This research concerns the AlSi10MnMg alloy, which introduces 50 to 75% (every 5%) of circulating scrap. This alloy is one of the most commonly used for producing gravity and pressure die-castings (HPDC), including engine parts and transport structural elements. Based on microscopic research, it was found that the increase in scrap content causes an increase in the share of iron, which results in pre-eutectic (from about 0.45 wt.% to 0.7 wt.% Fe) or even primary crystallization of iron phases (over 0.7 wt.% Fe), mainly the plate–needle phase β-Al₅FeSi. Its unfavorable morphology and size cause the formation of numerous shrinkage porosity areas, which has an impact on the reduction in mechanical properties (reduction in UTS and YS by approx. 16% and elongation by approx. 18%, compared to the AlSi10MnMg alloy with 50% scrap content). It was found that the increase in the share of recycled scrap (from 50 to 75%) can be used only when the manganese content is increased. Its effect is to change the morphology of the β-Al₅FeSi phase into α-Al₁₅(Fe,Mn)₃Si₂, whose crystallization occurs in the temperature range of 540 to 555 °C and increases slightly with increasing manganese addition. It is essential to consider the appropriate value of the Mn/Fe quotient, which should be about 1/2, because a higher value may cause the formation of a sludge factor. This work aimed to determine the limiting iron content (contained in the scrap) at which the sequence of the β-Al₅FeSi phase release (pre-eutectic or primary crystallization) changes. This sequence mainly affects the form of morphology, the dimensions of the β-Fe phase, and the proportion of shrinkage porosity.

Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO₂, Al₂O₃and Cs) were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting) technology, followed by plastic work (the KOBO method). The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

Titanium alloys belong to a group of the most advanced metal materials with increasing applications observed in recent years, mainly in the aircraft, shipbuilding, automotive and chemical industries as well as in medicine. In the paper, results of the study on changes in aluminium content in binary Ti-Al alloys during smelting in the vacuum induction melting (VIM) furnace are presented. The experiments were performed at 5 Pa and 1000 Pa, 1973 K and 2023 K. The investigations were conducted for alloys containing up to 49%mass Al. Each experiment began with loading an alloy sample (about 1000 g) into the graphite crucible placed in the induction coil of the furnace. After closing the furnace chamber, the pre-specified vacuum was generated with the use of a pump system. When the pressure level was stabilised, the crucible was heated up to the required temperature and the metal bath was held for 600 sec. During each smelting experiment, metal samples were collected and subjected to a chemical analysis. The Al loss rate in each experiment was not higher than 21%; it increased with temperature and reduced pressure in the device. It is assumed that the observed loss of aluminium during smelting is the effect of evaporation. The obtained values of Al concentration in the investigated alloys ensured that the aluminium overall mass transfer coefficient in the process could be estimated. The values of overall mass transfer coefficient were 0.88 to 1.66×10^-5 [m·s^-1]. Lack of clear effects of the alloy composition on the analysed process rate proves that it is not controlled by mass transfer in the liquid phase.