Effect of equal channel angular pressing die angle on corrosion behavior of bulk nanostructured metal

Equal channel angular pressing technique was used to process bulk nanostructured commercial pure titanium Cp2(Ti Cp2) and aluminium alloy 6061(Al6061). The samples were processed at two different die channel angles of 120 º and 126 º. Hardness test shows that the hardness for Al6061, using channel angle 120° ECAP-ed, has increase 15.55% while using channel angle 126° the increase was 14.89% compared to non-ECAP-ed sample. Hardness test for Ti Cp2 ,using channel angle 120° ECAP-ed has increase 32.89% while using channel angle 126° the increase was 27.05%. The hardness for this both materials have shown that Ti Cp2 has higher hardness compared to Al6061 since the highest increment is 5.84% for 120°ECAP-ed than 126°ECAP-ed for Ti Cp2 samples. The corrosion behavior of the ECAP-ed Al6061 was investigated in 3.5% sodium chloride (NaCl) solution relative to seawater concentration while Ti Cp2 was investigated in phosphate buffered saline (PBS) solution. Corrosion resistance on 120° ECAP-ed for both Al6061 and Ti Cp2 have shown improved corrosion behavior indicated by the least value of corrosion current density when compared to non-ECAP . By using channel angle 120°, Al6061 have shown the lowest corrosion current density (Icorr) value of 1.61E-7 while Ti Cp2 has also shown lowest Icorr value of 1.19E-08. This means ECAP-ed using 120° is the most noble sample with lowest corrosion value, when applied with current, among all samples

The corrosion resistance in artificial saliva of titanium and Ti-13Nb-13Zr alloy processed by high pressure torsion

In order to optimize and enhance the implant material properties, metallic materials may be modified by severe plastic deformation (SPD) procedures. One of the most attracting SPD methods is high-pressure torsion (HPT), which is method where deformation is obtained mainly by simple shear. In the present study ultrafine-grained titanium (UFG cpTi) and ultrafine-grained Ti-13Nb-13Zr (UFG TNZ) alloy were obtained by high pressure torsion (HPT) under a pressure of 4.1 GPa with a rotational speed of 0.2 rpm up to 5 rotations at room temperature. In order to analyse microstructure of materials before and after HPT process, scanning electron microscope (SEM) was used. The aim of this study was to determine the corrosion resistance of titanium and its alloy after HPT process. Electrochemical measurements were performed in artificial saliva with a pH value of 5.5 at 37 degrees C, in order to simulate the oral environment. The materials were analysed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. All examined materials showed good corrosion resistance, but results indicate that HPT process can improves corrosion resistance