Effect of Equal Channel Angular Pressing on the Structure, Mechanical and Corrosion Properties of Mg-Zn-Zr Alloy

Biocompatible magnesium alloys offer promise as materials for the manufacture of bioresorbable implants. This work is devoted to establishing rational modes of equal channel angular pressing (ECAP) of the Mg-8.6Zn-1.2Zr alloy in order to form a structural state with high mechanical properties and corrosion resistance. It is found that 1 cycle of ECAP at a temperature of 400 degrees C results in a noticeable increase in the tensile strength (up to 330 MPa), while the corrosion resistance decreases. Immersion tests indicate that, after 1 cycle of ECAP at 400 degrees C, the corrosion rate in Ringer's solution reaches 9 mm/year. It is suggested that the 2nd cycle of ECAP at a decreased temperature of 250 degrees C should be carried out to maintain the tensile strength at 325 MPa and increase the corrosion resistance to a level corresponding to the as-annealed state (6-8 mm/year). EBSD studies reveal that this behavior is associated with an increase in the number of special Sigma 13a, Sigma 15b and Sigma 17a boundaries in the structure after the 2nd ECAP cycle.