Preparation And Performances Of Mg-Zn-Ca Bulk Metallic Glass Matrix Composite Reinforced By Fe Particle With Electroless Copper Coating

Mg-Zn-Ca amorphous alloy has been widely concerned inthe field ofbiodegradable metallic biomaterials due to the excellent biodegradable properties.Similar to other Mg-based amorphous alloys,Mg-Zn-Ca amorphous alloygenerally has poor plasticity at room temperature,which severely limited its clinical application in biomedical field.In order to improve the plasticity of Mg-Zn-Ca amorphous alloy,Fe particles have been used as the ductile second phase to enhance the Mg-Zn-Ca amorphous alloy.However,in general,there are certain amount of rustson the surface of Fe particles,leading to serious crystallization of amorphous alloy matrix.It is unfavorable or harmful for the formation of the Mg-Zn-Ca amorphous structure of matrix.To reduce this adverse influence,the spherical,spray atomized iron powderswere treated by electroless copper plating andused as the reinforcement to enhance Mg-Zn-Ca amorphous alloy.The effect of copper plating on the glass formation ability?GFA?,mechanical properties and biodegradable behavior of Mg-Zn-Ca alloy were carefully studied.In this dissertation,orthogonal test method was used to optimize the preparation technology of electroless copper plating on iron particles.The major optimized technology parameters were concluded as the following:pH=13,temperature of 40⁵0?,the main salt concentration of 25³0 g/L.The spherical Fe particles after optimized plating treatment showed typical color of bright copper and have microstructure with fine grain.The copper coating coated on the Fe particles appearssmooth and dense surfaces at micro scale.The coated Fe particles were added into the Mg₆₆Zn₃₀Ca₄ amorphous alloy matrix,which has not caused the amorphous matrix to occurr significant crystallization.It is suggested that the copper plating process is in favor of the glass formation of such alloy systemswith weak GFA.The Fe/Mg₆₆Zn₃₀Ca₄ amorphous matrix composite sample was analyzedby Vickers hardness,which shows that the hardness of the composite is significantly higher than that of the amorphous alloy,Mg and AZ91.Moreover,in compression test,we have found that the fracture mode of the composite material belongs to typical shear fracture mode.Meanwhile,the fracture morphology shows typical vein like pattern which generally occurs in toughness BMGs.The fracture strength of the composite isup to 834 MPa and the specific strength reaches 2.79×10⁵ N·m/kg.Compared with Mg₆₆Zn₃₀Ca₄ amorphous alloy,Fe/Mg₆₆Zn₃₀Ca₄ amorphous matrix composite shows improved fracture strength and,enhanced specific strength and obvious plastic deformation characteristics.By simulated body fluid?SBF?cultivation,we have found that the hydrogen gas released behavior of Fe/Mg₆₆Zn₃₀Ca₄ amorphous composites is similar to that of Mg₆₆Zn₃₀Ca₄ amorphous sample and much weaker than that of the reference sample pure Mg.Fe/Mg66Zn30Ca4amorphous composites also shows better corrosion resistance in SBF than that of pure Mg.After immersion in SBF over 30 days,the Fe/Mg₆₆Zn₃₀Ca₄ sample was degraded completely,showing a good biodegradability properties.Therefore,it is demonstrated that the introduction of copper coated Fe particles has no obvious adverse effect on the biological degradation behavior of Mg₆₆Zn₃₀Ca₄ amorphous alloy.