The Preparation And Mechanical Properties Of The Matrix Material Of Rare-earth-magnesium Alloy For Medical Stent

For coronary heart disease patients with severe coronary artery stenosis, drug therapy can not effectively reverse the coronary arteries, so thoracic intervention or bypass surgery is required. And the advantage of interventional treatment is not only the effective solution to coronary stenosis but also the reduction of surgical risk. At present, the intervention materials such as cobalt, titanium, stainless steel may lead to vascular intimal hyperplasia and increase late thrombotic events after long-term implantation; and polymers such as biodegradable polylactic acid, due to their failure to meet the requirements of blood vessels supporting performance, the use of such materials is restricted. To address these material problems, this study has developed biodegradable magnesium alloy stent matrix material.This paper takes rare-earth-magnesium alloy with good biocompa-tibility as the subject of the study, and has adopted Mg-Y-Zr (WY=4.2%, WZr=0.5%) as the base alloy, analyze the influence of different amounts of Nd, Ce (La) Rare Earth Elements on microstructure and properties, and has prepared Mg-4.2Y-2.4Nd-0.6Ce (La)-0.5Zr (i.e.the WE43 alloy) with excellent performance.The study has also systematically analyzed the microstructure, biomechanical properties and fracture mechanisms of its cast, extruded and heat treatment state.According to the microstructure observation of WE43-cast,adding appropriate amount of rare earth elements Nd, Ce (La) into magnesium alloys can cause good grain refinement effect. The eutectic phase of rare earth gets enriched in the grain boundary. After T4 treatment, the rare earth element in the alloy solutes into the a-Mg matrix which strengthens the solid solution;after the T6 heat treatment, T6 condition alloy's microstructure is uniform.Grains precipitate a large number of dispersed Mg-Re phase,the age strengthening effect is obvious,its biomechanics overall performance is greatly improved,especially the elongation at high temperature is raised Cast alloy is deformed by hot extrusion after even annealing.It is found that there is follows the three steps:quasi-cleavage fracture of cast state,tendency ductile fracture of heat treatment state,then ductile fracture of extruded state and under high temperature.This paper has made detailed inquiry about the composition design, casting, heat treatment and extrusion of WE43 alloy and demonstrated the feasibility of bio-mechanical compatibility that the WE43 alloy can be used as controllable.