| Magnesium alloy possess excellent biocompatibility,mechanical compatibility and degradability.Currently,the major drawback of the magnesium alloy as implant materials is that they corrode too fast in physiological environment to meet the requirements mechanical integrity before the completion of bone tissue healing.Therefore,it is necessary to deve lop magnesium matrix composites with controllable corrosion rate and mechanical properties similar to human bone mechanics.In this paper,bioactive nano HA particles were introduced to the Mg-Zn-Ca alloy,the as-cast Mg-3Zn-0.2Ca-1HA composites were prepared.In order to further improve the comprehensive mechanical properties and corrosion resistance of the composite materials,the hot extrusion deformation of as-cast composites were adopted,extruded composite material were prepared.The microstructure,mechanical? corrosion properties and biocompatibility of extruded composites were observed,test and evaluation.In addition,we combined the conventional extrusion and channel angle extrusion of as-cast composites,the combined variable ECAP deformation of the extruded composite material microstructure and corrosion behavior were studied.The results of the study indicate that:1.The phase of the Mg-3Zn-0.2Ca-1HA composite of as-cast and extruded is mainly composed of ?-Mg,Mg2 Ca and Ca2Mg6Zn3.Comparison the result of microstructure can be drawn: the grain size of the composites was reduced about fourteen times,composite particle agglomeration also improved in a certain extent.The distribution of HA particles was arranged in fiber.The tensile strength is 367.252 MPa,the yield strength is 350.884 MPa,the elongation is 10.786% respectively.Electrochemical and the vitro immersion tests showed that the corrosion resistance of the extruded composites was better than the as-cast composites.Cytotoxicity test showed that Mg-3Zn-0.2Ca-1HA composite composed good cell compatibility.2.With the ECAP times increasing,4 passes of Mg-3Zn-0.2Ca-1HA composite TD section after ECAP has the minimum grain size.Mg-3Zn-0.2Ca-1HA with different times of different sections by ECAE is composed of ?-Mg,besides,Mg2Zn3,Mg4Zn7,Ca10(PO4)6(OH)2.4 passes' s texture greatly diffuse,the maximum density value is 5.985,strength is lower.Texture diffusion of 8 passes becomes small,the maximum density value is 3.220,strength is lower.The electrochemical test conclusion is:4 pass has best corrosion resistance.The improved technology is superior to the non-improved technology. |
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