An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction ...An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction （XRD） was used to identify the phases. Microstructure and properties of laser melted layer of AZ31B magnesium alloy were observed or tested by means of optical microscope （OM）, scanning electron microscope （SEM）, micro-hardness equipment and electrochemical corrosion equipment etc. The results show that the microstructure of laser melted layer becomes finer significantly and uniform. Compared with the substrate, the content of β-Mg17 Al12 phase of melted layer decreases comparatively. Microhardness of the laser melted layer is improved to 50 -95 HV0. 05 as compared to 40 -45 HV0.05 of the AZ31B Mg alloy substrate. The results of electrochemical corrosion show that the corrosion resistance of laser surface melted layer has been improved.展开更多
The as-cast microstructure, mechanical properties and casting fluidity of ZA84 alloy containing TiC were investigated. The experimental results indicate that adding 0.5wt%TiC to ZA84 alloy can refine the as-cast micro...The as-cast microstructure, mechanical properties and casting fluidity of ZA84 alloy containing TiC were investigated. The experimental results indicate that adding 0.5wt%TiC to ZA84 alloy can refine the as-cast microstructure, and do not cause the formation of any new phase. After 0.5wt%TiC was added to the ZA84 alloy, the morphology of ternary phases on the grain boundaries changed from coarse quasi-continuous net to fine disconnected net, and the distribution of ternary phases became dispersive and homogeneous. At the same time, the tensile properties of ZA84＋0.5TiC alloy at room temperature were comparable to those of AZ91D alloy, and were higher than those of ZA84 alloy. At 150 ℃, the tensile and creep properties of ZA84＋0.5TiC alloy were also higher than those of ZA84 and AZ91D alloys. In addition, compared with the AZ91D alloy, the casting fluidity of ZA84＋0.5TiC alloy was slightly poor, but better than that of ZA84 alloy. The reason could be related to the effect of TiC on the solidification temperature range of ZA84 alloy.展开更多
Magnesium （Mg） based metals possess unique features of biodegradation that can be used for different purposes. In this study, two tumor cells, MG63 and KB, were cultured directly on a pure Mg with and without MAO co...Magnesium （Mg） based metals possess unique features of biodegradation that can be used for different purposes. In this study, two tumor cells, MG63 and KB, were cultured directly on a pure Mg with and without MAO coating to evaluate their cytotoxic effects on the tumor cells. It was found that both MG63 cells and KB cells adhered better on the surface of the coated Mg samples than those on the pure Mg samples. However, the survivals of two kinds of tumor cells were obviously inhibited on both Mg samples with and without coating, compared with that on the pure titanium. In addition, the survival of MG63 cells was more susceptive to the Mg degradation compared with the KB cells. Thus, the application of such effect should take account of that the degradation of Mg based metal may result in different cytotoxic effect on different cells.展开更多
基金The research is supported by the Shanxi Natural Science Foundation （No. 2008011044）.
文摘An attempt has been made to improve the surface properties of AZ31B magnesium alloy through solid solution hardening and refinement of microstructures using a CO2 laser as a heat generating source. X-ray diffraction （XRD） was used to identify the phases. Microstructure and properties of laser melted layer of AZ31B magnesium alloy were observed or tested by means of optical microscope （OM）, scanning electron microscope （SEM）, micro-hardness equipment and electrochemical corrosion equipment etc. The results show that the microstructure of laser melted layer becomes finer significantly and uniform. Compared with the substrate, the content of β-Mg17 Al12 phase of melted layer decreases comparatively. Microhardness of the laser melted layer is improved to 50 -95 HV0. 05 as compared to 40 -45 HV0.05 of the AZ31B Mg alloy substrate. The results of electrochemical corrosion show that the corrosion resistance of laser surface melted layer has been improved.
基金Funded by the National Natural Science Funds for Distinguished Young Scholar in China(No.50725413)the Major State Basic Research Develop-ment Program of China(973)(No.2007CB613704)+1 种基金the Natural ScienceFoundation Project of CQ CSTC(No.2007BB4400)Chongqing Scienceand Technology Commission in China (No.2006AA4012-9-6)
文摘The as-cast microstructure, mechanical properties and casting fluidity of ZA84 alloy containing TiC were investigated. The experimental results indicate that adding 0.5wt%TiC to ZA84 alloy can refine the as-cast microstructure, and do not cause the formation of any new phase. After 0.5wt%TiC was added to the ZA84 alloy, the morphology of ternary phases on the grain boundaries changed from coarse quasi-continuous net to fine disconnected net, and the distribution of ternary phases became dispersive and homogeneous. At the same time, the tensile properties of ZA84＋0.5TiC alloy at room temperature were comparable to those of AZ91D alloy, and were higher than those of ZA84 alloy. At 150 ℃, the tensile and creep properties of ZA84＋0.5TiC alloy were also higher than those of ZA84 and AZ91D alloys. In addition, compared with the AZ91D alloy, the casting fluidity of ZA84＋0.5TiC alloy was slightly poor, but better than that of ZA84 alloy. The reason could be related to the effect of TiC on the solidification temperature range of ZA84 alloy.
基金support of the National Natural Science Foundation of China(No.30970715 and No.2012CB619101)Chinese Academy of Sciences,Applied Research of Bioactive Bone Implanted Materials(No.KGCX2YW-207)
文摘Magnesium （Mg） based metals possess unique features of biodegradation that can be used for different purposes. In this study, two tumor cells, MG63 and KB, were cultured directly on a pure Mg with and without MAO coating to evaluate their cytotoxic effects on the tumor cells. It was found that both MG63 cells and KB cells adhered better on the surface of the coated Mg samples than those on the pure Mg samples. However, the survivals of two kinds of tumor cells were obviously inhibited on both Mg samples with and without coating, compared with that on the pure titanium. In addition, the survival of MG63 cells was more susceptive to the Mg degradation compared with the KB cells. Thus, the application of such effect should take account of that the degradation of Mg based metal may result in different cytotoxic effect on different cells.
