Mechanical properties and corrosion behavior of titanium surface biocomposites reinforced with Al2O3 particles fabricated by friction stir processing

This study aims to investigate the effects of Al2O3 micro and nanoparticles on the microstructure, mechanical, and corrosion properties of the pure titanium surface biocomposites fabricated by friction stir processing (FSP). The microstructure, mechanical, and corrosion properties of samples were evaluated using optical microscopy (OM), electron-backscattered diffraction system (EBSD), hardness tests, tensile tests, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) analyses. The OM and EBSD analyses proved the highest amount of grain refinement associated with the formation of strain-free recrystallized grains by applying FSP at the presence of Al2O3 nanoparticles. However, the amount of micro-strain and grain size of FSPed titanium without particles and with Al2O3 microparticles were much higher than that of samples with Al2O3 nanoparticles. Notably, the hardness values improved by about 33 % and 52 % by introducing Al2O3 microparticles and nanoparticles, respectively. Mechanical tests demonstrated a noticeable enhancement in the tensile strength of the samples, from 200 MPa for the sample processed without Particles to the highest amount of 294 MPa for that processed in presence of nanoparticles. The corrosion test results revealed a significant improvement in the corrosion resistance of the titanium samples by adding Al2O3 nanoparticles in which the corrosion potential increased from 0.244 to 0.192 V and charge transfer resistance from 394 to 794 k omega cm2.