The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti₂₀Ta₂₀Nb₂₀(ZrHf)_20−xMo_x (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young’s modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers’ solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers.

Laser cutting technology is one of the basic approaches used for thermal processing of parts fabricated from almost all engineering materials. Various types of lasers are utilized in the industry with different attendant gases such as nitrogen or argon. When the laser beam interacts with a metal surface, the area underneath is heated to the melting point. This liquid or vaporized metal is ejected from the kerf area to the surrounding atmosphere by attendant gas and becomes undesirable waste in the form of powder. In the presented work, the X-ray diffraction, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy methods were used to analyze AISI 304 stainless steel, which was cut by a semiconductor fiber laser, and the waste powder generated during the laser cutting process. The results suggest that this waste material may be reused for industrial applications such as additive manufacturing.

The presented work aimed to investigate the influence of the hafnium/(zirconium and molybdenum) ratio on the microstructure, microhardness and corrosion resistance of Ti₂₀Ta₂₀Nb₂₀(ZrMo)_20−xHf_x (where x = 0, 5, 10, 15 and 20 at.%) high entropy alloys in an as-cast state produced from elemental powder and obtained via the vacuum arc melting technique. All studied alloys contained only biocompatible elements and were chosen based on the thermodynamical calculations of phase formation predictions after solidification. Thermodynamical calculations predicted the presence of multi-phase, body-centered cubic phases, which were confirmed using X-ray diffraction and scanning electron microscopy. Segregation of alloying elements was recorded using elemental distribution maps. A decrease in microhardness with an increase in hafnium content in the studied alloys was revealed (512–482 HV1). The electrochemical measurements showed that the studied alloys exhibited a high corrosion resistance in a simulated body fluid environment (breakdown potential 4.60–5.50 V vs. SCE).