Research On Heat Treatment And Extrusion Process Of Mg-Zn-Mn-Ca Alloy

Magnesium shows huge application value in aspects such as structurematerial and function material for the reason of abundant mineral products,lightweight, easy processing and forming and excellent physical performance andso on. Pure magnesium shows poor mechanical property， properties ofmagnesium may be improved by the way of adding alloying elements and heattreatment as well as hot working process. Magnesium possesses favourablebiodegradability and biocompatibility so that it has an obvious advantage in thearea of implant materials. The density and elasticity modulus of magnesium areclose to human bone, moreover, the applying of magnesium implant materialcould avoid secondary operation to remove, so magnesium can be a potentialsubstitutes for the traditional implant materials. For biological magnesium boneplates of excellent performance, the nutrient elements of Zn, Ca and Mn wereadded into pure magnesium to prepare the alloy of Mg-2Zn-1.0Mn-0.5Ca, thenthe heat treatment and batten extrusion processing conducted on the alloy.The paper is built on the Mg-2Zn-1.0Mn-0.5Ca alloy, microstructure andperformance of the alloy was detected and analyzed by optical microscope, X-raydiffractometer, scanning electron microscope, transmission electron microscopy,microhardness tester and universal testing machine. At the same time, the effectof homogenizing, solid solution and aging treatment was analyzed, parameters ofheat treatment process got optimized. The effect of extrusion temperature anddeformation degree was also analyzed in the batten extrusion process. Solidsolution and aging treatment were conducted on the as-extruded alloy, theperformance changes were detected.This study found that the alloy homogenization process speed up along withthe rise of temperature, higher temperature could shorten aging time properly. Alloy achieve the microhardness peak after homogenization for8h, and strengthand plasticity improved. The high temperature in solid solution can give rise tograin growth quickly, which is harmful to the performance of alloy. In the grainorganization of as-extruded alloy, the distribution of grain size shows regional,and the change of extrusion temperature and deformation degree could alsoinfluence the microstructure and grain size. Alloy which extruded into batten of5mm thickness at325℃possesses the most even and small grains as well asexcellent performance. During the solid solution process after extrusion, grainsgrew up gradually and hardness decreased. The plasticity and strength could bebetter by single-stage or two-stage aging after solid solution.