Effects of ECAP Extrusion on the Microstructure, Mechanical Properties and Biodegradability of Mg-2Zn-xGd-0.5Zr Alloys

Effects of equal channel angular pressing (ECAP) extrusion on the microstructure, mechanical properties and biodegradability of Mg-2Zn-xGd-0.5Zr (x = 0, 0.5, 1, 2 wt%) alloys were studied in this work. Microstructure analysis, tensile test at ambient temperature, immersion test and electrochemical test in Hank's solution were carried out. The results showed that Gd could further enhance the grain refinement during the ECAP extrusion. Both Gd addition and ECAP extrusion could improve the mechanical properties of the alloys, and the extrusion played the dominant role. Minor addition of Gd (0.5-1 wt%) could obviously enhance the corrosion resistance of the alloys. To some extent, ECAP extrusion improved the corrosion resistance of the alloys due to the change of second phases distribution and the refinement of grains. Further increase in extrusion pass was detrimental to the improvement of the corrosion resistance as a result of increment of the grain boundaries.