Study On Preparation Processes, Microstructures And Mechanical Properties Of Small Diameter Magnesium Alloy Wires

Tissue engineering materials is one of the study focuses in biological medical materials field,such as the blood vessel stenter.Magnesium alloy has excellent biological compatibility. In comparing with Ti alloy and stainless steel,it can be dissolved in fluid blood.As a result,the plugged blood vessel can be got recovery.To be as stenter,Mg alloy should possess certain ductility.Therefore,preparing Mg alloy wire with good strength and elongation,and studying its microstructure and properties are very important.In this paper,AZ91D,ZK60 and Mg-5Bi-1.5Ca Mg alloy wires with diameters ofφ1mm～φ2mm were prepared and as-extruded as well as T5 heat treated microstructures were observed via optical microscope,scanning electronic microscope and X-ray diffraction. Mechanical properties were tested.The results show that(1)the optimal extrusion temperatures, extrusion presses and extrusion rates are 410℃,10MPa and 30mm/min for AZ91D wires; 384℃,8MPa and 15mm/min for ZK60 wires;350℃,9MPa and 120mm/min for Mg-5Bi-1.5Ca wires,respectively as well as extrusion ratios 16.08 and lube MoS₂;(2)microstructures consist of refined equiaxed grains with average grain sizes ranging from 5μm to 10μm.T5 heat treatment can influence the as-extruded microstructures and change the morphology and distribution of precipitates.After T5 heat treatment,the microstructures of AZ91D and Mg-5Bi-1.5Ca hadβ-Mg₁₇Al₁₂and Mg₃Bi₂ precipitates.As the aging time prolongs,coarsening of Mg₃Bi₂ happened;(3)the tensile strength,yield strength and elongation are～342MPa,～257MPa and 16.7%for AZ91D wires;～301MPa,～231MPa and 21.2%for ZK60 wires;～177MPa,～102MPa and(5.9～8.4)%for Mg-5Bi-1.5Ca wires,respectively.After T5 heat treatment,Mechanical properties of AZ91D and Mg-5Bi-1.5Ca wires were improved to some extent.The elongation of Mg-5Bi-1.5Ca wires is up to 12.5%at aging 8 hours;(4)dynamic recrystallization occured during the hot extrusion.