Effect of Mechanical Alloying and Sintering Environment on the Crystallographic Evolution, Microstructure, Mechanical and Corrosion Properties of Porous Ti4Al4Co Alloy

Abstract

Three group of porous Ti4Al4Co samples made of (i) unmilled powder and vacuum sintered (S1), (ii) milled powder and vacuum sintered (S2), and (iii) milled powder sintered in open atmosphere (S3) were prepared. Phase change, crystallite size and lattice strain variations due to powder milling and sintering were examined by SEM and XRD. To evaluate mechanical property, alloy samples were subjected to the uniaxial compression test. For corrosion analysis, Tafel plot was plotted using electrochemical corrosion system in simulated body fluid (SBF) as electrolytic medium. From the obtained results, it was found that significant microstructural transformation takes place due to milling and change in sintering atmosphere. Sample S1 possessed 139 MPa compressive strength, which was about 48% and 76% higher than samples S2 and S3 respectively. Corrosion current density for S3 was found as 5.5\u2009±\u20090.3 μA/cm2 which is 7 and 12 times lower than S2 and S1 samples.