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In this study, the microstructure and defects of an Al‐Mn‐Mg‐Zr alloy produced by the Powder Bed Fusion–Laser Beam (PBF‐LB) technology are investigated. The influence of the process parameters on the microstructure and defects is demonstrated. Aluminum alloys are usually prone to cracking during solidification. However, finding the optimal parameters of the PBF‐LB process yielded three‐dimensional specimens of Al‐Mn‐Mg‐Zr alloy with densities reaching 99.6% of the theoretical value, free from cracks. It is shown that manganese not only precipitates as a brittle Al6Mn intermetallic compound after solidification but also forms a supersaturated solid solution of manganese in aluminum. The influence of the process parameters on the surface roughness of the manufactured samples and their microhardness was evaluated. It is also shown that the cooling rate of the melt pool has an effect on the microstructure of the samples obtained at the optimal process parameters. [ABSTRACT FROM AUTHOR]

The positive effect of plasma electrolytic treatment on CrWMn tool steel to increase the wear resistance of its surface is shown. The effect of plasma electrolytic nitriding and subsequent polishing on the structure, phase and elemental composition, microhardness of the surface layer, and surface morphology is established. Steel nitriding leads to the formation of a modified surface layer including Fe2–3N iron nitride and nitrogen martensite, below which hardening martensite is formed, reaching a microhardness value of 1200 HV. Subsequent polishing leads to a decrease in surface roughness by 42–68%. Tribological tests were carried out according to the shaft-bushing scheme. A decrease in the friction coefficient and weight wear of up to 2.6 and 30.1 times, respectively, is shown. The formed structure of the surface layer compensates for the effect of the counter body and determines the destruction of friction bonds by plastic displacement. The wear mechanism has been established and is defined as fatigue wear under dry friction and plastic contact. [ABSTRACT FROM AUTHOR]

Zr57Cu15Ni10Nb5 (more known as Vit-106) is a promising zirconium-based alloy with a high glass-forming ability, and belongs to the so-called bulk metallic glasses (BMG). Workpieces with a size of around one centimeter in all three dimensions can be obtained from a BMG alloy by casting. However, further increasing the cast size decreases the cooling rate and thus induces crystallization. Selective laser melting (SLM) is a well-known technique to overcome size limitations for BMGs because a workpiece is built by the addition of multiple melt portions in which the cooling rate is kept above the critical one. Currently, BMG parts obtained by SLM suffer from partial crystallization. The present work studies the influence of SLM process parameters on the partial crystallization of Vit-106 by metallography and the influence of the microstructure on mechanical properties by microhardness and wear resistance testing. Submicron crystalline inclusions are observed in an amorphous matrix of a Vit-106 alloy obtained by SLM. The size and the concentration of the inclusions can be controlled by varying the laser scanning speed. It is shown that submicron crystalline inclusions formed in the amorphous matrix during SLM can favorably affect microhardness and wear resistance. [ABSTRACT FROM AUTHOR]