COMBINED TECHNOLOGY OF ELECTRO-SPARK ALLOYING AND THERMAL DIFFUSION BORIDING OF STEEL

The process of thermal diffusion boriding is well known and used throughout the world. It has a number of unique properties, such as high hardness and wear resistance under abrasive wear conditions. Continuous boride layers have increased brittleness, which is related with the elastic properties of borides. In this work, we studied the features of the formation of surface layers onlow-carbon steels after electro-spark alloying, and not by continuous processing of the entire surface of the steel, but only sections and subsequent thermal diffusion boriding from powder medium. Such complex technology enables to form discrete regular and irregular layers, which have a number of advantages, in particular, reduced brittleness. The structure and phase composition of the combined coating growth kinetics of the diffusion layer during the thermal diffusion boriding, are investigated. The creation of the considered composite layers with FeB and Fe2B phases with reduced brittleness will significantly expand their area of application, for example, for working conditions with moderate impact loads.

Mechanical and Microstructural Characterization of Powder Medium Entropy Alloy

High and medium entropy alloys are an intriguing new material class, revered for possessing an exceptional combination of primarily mechanical properties. In this scientific contribution, the CoCrNi medium entropy alloy has been produced by a combination of mechanical alloying (MA) and spark plasma sintering (SPS). The properties have been characterized by means of X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and tensile testing. The powder after the MA process exhibited nano-grained microstructures with fine chemical homogeneity. After the SPS densification, a full density of the bulk products has been achieved. The microstructure was composed of major FCC phase and minor secondary precipitates. The materials possessed high strength values coupled by reasonable ductility levels, therefore overall satisfactory results.