In the present work, the microstructure, phase constitution, and corrosion behavior of binary Sn–xZn alloys (x = 5, 9 and 15 wt.%) were investigated. The alloys were prepared by induction melting of Sn and Zn lumps in argon. After melting, the alloys were solidified to form cast cylinders. The Sn–9Zn alloy had a eutectic microstructure. The Sn–5Zn and Sn–15Zn alloys were composed of dendritic (Sn) or (Zn) and eutectic. The corrosion behavior of the Sn–Zn alloys was studied in aqueous HCl (1 wt.%) and NaCl (3.5 wt.%) solutions at room temperature. Corrosion potentials and corrosion rates in HCl were significantly higher compared to NaCl. The corrosion of the binary Sn–Zn alloys was found to take place by a galvanic mechanism. The chemical composition of the corrosion products formed on the Sn–Zn alloys changed with the Zn weight fraction. Alloys with a higher concentration of Zn (Sn–9Zn, Sn–15Zn) formed corrosion products rich in Zn. The Zn-rich corrosion products were prone to spallation. The corrosion rate in the HCl solution decreased with decreasing weight fraction of Zn. The Sn–5Zn alloy had the lowest corrosion rate. The corrosion resistance in HCl could be considerably improved by reducing the proportion of zinc in Sn–Zn alloys.

Deoxidized oxygen free copper C12200, 1 mm in thickness, was welded to 1-mm thick AISI 304 stainless steel with disk laser. The butt-welded joints were produced with different welding parameters. Full factorial design of experiment (DoE) approach consisting of three factors and two levels was utilized. Laser powers used for welding were 1.3 and 1.9 kW and welding speeds of 20 and 30 mm/s. Two beam offsets were tested, namely, 100 μm toward copper side and 200 μm toward AISI 304 steel. It was found that beam offset possesses the largest influence on the welded joints’ tensile strength. Tensile strengths attained values more than 3.7 times higher in comparison to the AISI 304 steel beam offset. When lower laser power was used, the higher tensile strength was attained for copper sheet offset. Higher microhardness was observed when laser beam was offset to AISI 304 steel side. The average microhardness of the weld metal was higher than that of the weaker base material, copper sheet. Energy dispersive X-ray spectroscopy (EDS) analysis confirmed the heterogeneity in elemental composition across the welded joint interface, being lower when laser beam was offset to AISI 304 steel side. On the other hand, the copper content dropped to the average composition of weld metal at the distance of about 140 μm from copper-weld metal interface.

Purpose: This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied. Design/methodology/approach: It was found to contain a Sn matrix, where both Ag phase – ɛ-Ag₃Sn – and Ti phases ɛ-Ti₆Sn₅ and Ti₂Sn₃ – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials. Findings: X-ray diffraction analysis proved the presence of new NTi and AlTi₂ phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu₃Sn and Cu₆Sn₅ phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa. Originality/value: The present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.