In this study, the addition of Sn on the microstructure of Zn 1.6 wt.% Al 1.6 wt.% Mg alloy was studied. Currently, the addition of Sn into Zn-Al-Mg based systems has not been investigated in detail. Both as-cast and annealed states were investigated. Phase transformation temperatures and phase composition was investigated via DSC, SEM and XRD techniques. The main phases identified in the studied alloys were η(Zn) and α(Al) solid solutions as well as Mg₂Zn₁₁, MgZn₂ and Mg₂Sn intermetallic phases. Addition of Sn enabled the formation of Mg₂Sn phase at the expense of Mg_xZn_y phases, while the overall volume content of intermetallic phases is decreasing. Annealing did not change the phase composition in a significant way, but higher Sn content allowed more effective spheroidization and agglomeration of individual phase particles.

The Royalloy steel was boronized at 1173, 1223, 1248, 1273 or 1323 K for 1, 3, 5, 7 or 10 h using a Durborid powder mixture. The boronized samples were analyzed by scanning electron microscopy, X-ray diffraction and Vickers microhardness testing. The kinetic activity of boronized layers growth obeys the parabolic law, and the maximum thickness was 182 ± 10 µm. The thickness of FeB makes up to 40% of the total layer thickness. The obtained layers have two phases, which were composed of FeB and Fe₂B phases, except for the sample boronized at 1173 K for 1 h which had an Fe₂B layer only. The microhardness of the Fe₂B phase had a range of 1370–1703 HV_0.1, and that of the FeB phase was within 1727–2231 HV_0.1. During the boronizing process, the chromium created extra particles with the highest amount of chromium in the transient region. The highest amount of silicon was observed at the boride layer/substrate interface. The amount of manganese was slightly lower in the boride layers compared to the amount in the substrate. Finally, the integral diffusion model was applied to determine the boron activation energies in the FeB and Fe₂B layers, and this was followed by a comparison with the literature data.

In the present work, the corrosion behavior of the Mg₂Sn alloy (Mg_66.7Sn_33.3, concentration in at.%) has been studied. The alloy was prepared from high purity Sn and Mg lumps by induction melting in argon. The alloy was composed of intermetallic Mg₂Sn with a small amount of Mg₂Sn + (Sn) eutectic. The corrosion behavior was studied by hydrogen evolution, immersion, and potentiodynamic experiments. Three aqueous solutions of NaCl (3.5 wt.%), NaOH (0.1 wt.%) and HCl (0.1 wt.%) were chosen as corrosion media. The alloy was found to be cathodic with respect to metallic Mg and anodic with respect to Sn. The corrosion potentials of the Mg₂Sn alloy were −1380, −1498 and −1361 mV vs. sat. Ag/AgCl in HCl, NaCl and NaOH solutions, respectively. The highest corrosion rate of the alloy, 92 mmpy, was found in aqueous HCl. The high corrosion rate was accompanied by massive hydrogen evolution on the alloy’s surface. The corrosion rate was found to decrease sharply with increasing pH of the electrolyte. In the NaOH electrolyte, a passivation of the alloy was observed. The corrosion of the alloy involved a simultaneous oxidation of Mg and Sn. The main corrosion products on the alloy surface were MgSn(OH)₆ and Mg(OH)₂. The corrosion mechanism is discussed and implications for practical applications of the alloy are provided.

Corrosion behaviour of Sn (0.0, 0.5, 1.0, 2.0 and 3.0 wt.%)-doped Zn 1.6 wt.% Al 1.6 wt.% Mg alloys exposed to salt spray testing was investigated. Intergranular corrosion was observed for all alloys in both as-cast and annealed states. However, due to microstructure spheroidisation in the annealed samples, potential intergranular corrosion paths are significantly reduced. Samples with 0.5 wt.% of Sn showed the best corrosion properties. The main corrosion products identified by XRD analysis for all samples were simonkolleite and hydrozincite. Occasionally, ZnO and AlO were identified in limited amounts.

The microstructure of materials is shaped not only by their chemical composition, but also by the thermomechanical processes used during the processing of a specific piece. The correct interpretation of the microstructure gives a rich source of information. This consists of several related steps, such as segmentation. Successful segmentation enables the qualitative as well as quantitative analysis of the individual microstructure components. The current paper deals with the segmentation and classification of four basic microstructure components of the Zn-Al-Mg-Sn alloy system. This is attempted with the help of several image processing techniques, where thresholding is the main one used. The investigated samples are the cast and annealed Zn-Al-Mg-Sn alloy bulks. The input data for this analysis are the SEM BSE images. These were taken for all alloys with a varying Sn content, covering a significant area of each investigated sample at different zoom levels. A semiautomatic algorithm running under Matlab is introduced. It addresses several tasks, such as preprocessing, noise filtering and decision methods. For the individual procedures, the time requirements for their execution are also indicated.

Recent advances in laser technologies offer significant flexibility in the additive manufacturing domain. Extensive work was focused on material processing using laser-directed energy deposition for repairing parts. This pilot study investigated the use of selective laser melting (SLM) for depositing a superior material such as CoCr on an existing stainless steel base. The interface between these dissimilar materials was analyzed. During fabrication, both metals were gradually mixed in the liquid state as the first CoCr powder layer was melded on the steel base without obvious defects. According to SEM and EDAX, the heat-affected zone has a limited depth (<20 µm). XRD patterns recorded across the CoCr–304 interface show a homogenous mixture of γ(Fe) and α(Co) solid solutions. The microporosity calculated by CT was under 0.5%. Microhardness was measured at and near the interface region, showing that the intermixing zone has high hardness (470–480 HV1), which may be related to the fine-grained microstructure. Mechanical testing reveals that the adhesion strength at rupture is 35% higher compared with the ultimate tensile strength of 304 steel. This adhesion strength can be attributed to the complete melting of CoCr particles after laser irradiation and to the reduced thickness of the HAZ and the IZ.