Characterization of structural, mechanical, tribological and corrosi̇on properties of cocrfemnnitix high entropy alloys manufactured by powder metallurgy and selecti̇ve laser melting methods

In this thesis, CoCrFeMnNiTix High Entropy Alloy (HEA) materials were produced by powder metallurgy (P/M) and selective laser melting (SLM) methods. The effects of P/M and SLM methods on the structural, mechanical, and corrosion properties of the parts produced were investigated with both production methods. Structural and morphological analyses of CoCrFeMnNiTix powder and samples were carried out with X-ray diffractometers, 3D profilometer, scanning electron microscopes, energy dispersive spectroscopy, and optical microscopes. In order to obtain tribological analyses, experiments were carried out in linear reciprocating order under room conditions. Electrochemical corrosion experiments were measured by the potentiodynamic polarization method in a 3.5% NaCl solution. Samples mechanically alloyed in the P/M method for 300 minutes and then hot pressed at 600°C-650 MPa (HEA-HP-8) and YEA-1 specimens (0° orientation) produced by SLM with optimum laser fabrication parameters in different structural orientations exhibited superior mechanical and surface properties. Structural, morphological, mechanical, tribological, and corrosion analyses were performed by adding 3% and 5% Ti to the alloy powders of HEA-HP-8 and YEA-1 (0° build) samples. In both production methods used, an increase in microhardness values and a significant improvement in wear rates were observed in parallel with the increasing Ti addition. While the HEA-HP-10 sample produced with TM with 5% Ti addition and the YEA-3 sample produced with SLM exhibited the best mechanical and wear properties, their corrosion behavior was lower than the other samples. While SLM samples exhibited higher filling rates and corrosion resistance than TM samples, they exhibited lower wear rates and hardness values.