| With the increasing demand for medical materials, biodegradable materials have developed rapidly in recent years. Magnesium alloys are essential elements of human metabolism, so have good biocompatibilitys. And magnesium alloys are excellent advantages of mechanical properties. Because there are many advantages, magnesium alloys are becoming the most promising biodegradable materials. But magnesium has the worse of corrosion resistance, because of its chemically active. At present, devices of magnesium implanted have failure in advance in biodegradable materials, due to excessive corrosion. Magnesium alloys have strong application in the biodegradable magnesium，on the basis of relatively mature research of commercial magnesium alloys in AZ series. The object of study are AZ80and AZ80+1Nd magnesium alloy in this paper.The corrosion of two kinds of alloys in simulated body fluids in different heat treatment process has been investigated detailedly in the paper. It is found by the experiment that heat treatment has affected on corrosion of the two kinds of alloys. The corrosion of two kinds of alloys in simulated body fluid in different PH process and the influence of each ion in simulated body fluids on the corrosion resistance of alloys, have been investigated detailedly. Corrosion behavior of alloys in simulated body fluids is thoroughly investigated using immersion hydrogen evolution, get weight loss and electrochemical experiments. The corrosion morphology change and corrosion types have been investigated through analysis of corrosion between macro shots and microscopic. Corrosion products are analyzed by XRD.Through experiments can be seen that the corrosion resistance of solid solution state is poor in AZ80+1Nd and AZ80alloys, but the corrosion resistance of solution+ageing state have been increased firstly, and then decreased with aging’s time increasing. AZ80+1Nd alloy’s corrosion resistance is better than AZ80alloy, due to form stable phase AlNd and Al2Nd with Nd addition. The results of electrochemical experiments show that heat treatment has a significant impact on the anodic dissolution. AZ80+1Nd alloy has little change in the average of corrosion rate and hydrogen evolution, especially hydrogen evolution is2.8ml after solution+36h ageing treatment, and the average of corrosion rate is0.0433mg/cm2day.Therefore,AZ80+1Nd alloy may be further studies for biological magnesium alloys. Meanwhile, it can be seen that corrosion types of two kinds of alloys are pitting and filamentous corrosion from morphology analysis of corrosion products. The main phase of corrosion product is Mg(OH)2, but Mg3(PO4)2、MgS2O7and MgCO3still exist.It is found by immersion hydrogen evolution, get weight loss for as‐cast AZ80and AZ80+1Nd alloys in different PH value after corrosion in simulated body fluids, results show: PH value is inversely proportional with two kinds of alloy corrosion speed, corrosion rate decreases with PH value increasing. Results of electrochemical analysis show the self‐corrosion potential increases gradually, the self‐corrosion current density decreases gradually, and corrosion rate of alloys decreases gradually, with the PH value increasing.The corrosion situation in different ions solution is thoroughly investigated using the as‐cast AZ80and AZ80+1Nd alloys, it is found that accelerated corrosion in simulated body fluids are Cl‐and SO42‐ions, and slow down corrosion are HPO42-, H2PO4-, HCO3-ions and glucose, especially corrosion of HPO2‐4and H2PO4-ions are more slower. Corrosion types are pitting and filamentous corrosion, and the main phase of corrosion product is Mg(OH)2. It is found that the formation of Mg3(PO4)2is protective in the solutions containing HPO42-and H2PO4-ions. At the same time, there is a little MgCO3in the solution containing HCO3-ion, and glucose is not directly involved in the formation of corrosion products. |
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