Electrochemical behavior in simulated body fluid of Mg-Ca-Zn-TiH₂alloy pre-treatment prepared by mechanical milling

Magnesium alloys were known to have a rapid corrosion rate, leading to material disintegration and eventually implant failure. The study aims to evaluate porous Mg-Ca-Zn alloys as biodegradable implants. The in vitro biocorrosion behavior of magnesium alloys metallic foam Mg-1Ca-3Zn was manufactured via powder metallurgy with a different variation TiH2 used as a foaming agent and different heat treatment routes, i.e., preheated at 450 °C and without preheated followed by sintering at 550 °C for 3 hours. The corrosion behavior was studied through the immersion test and electrochemical test in Hank's solutions. Immersion test results indicated that samples with 3 % TiH2 have the highest pH increment during the test leading to pronounced spallation. After exposure, the SEM results of the studied alloys revealed microcracks as well as volcano-like structure formation. The corresponding EDX measurement revealed that the studied alloys with TiH2 contents:S 1.5 wt.% show some Ca and P traces instead of Mg and O as corrosion products. Whereas samples with 3% TiH2 predominantly contained only Mg and O. Potentiodynamic polarization experiments conducted at 37 °C and pH 7.4 indicated the increased biodegradation rates resulted from the porous structure preheated samples. The results showed that preheating at 450 °C before sintering at 550 °C impairs the corrosion resistance due to the pore formation. The addition of 3 % TiH2 leads to corrosion layer formation consisting of predominantly Mg(OH)2.