Ca对医用Mg-4Zn合金轧制板材组织与性能的影响

Effects of Ca Addition on Microstructure and Properties of the As-rolled Mg-4Zn Alloy Plate for Biomedical Application

采用金相分析、扫描电镜分析和拉伸测试等手段研究了Ca含量(质量分数0.3%,0.6%和0.9%)对高应变速率轧制Mg-4Zn基合金板材显微组织、力学性能和耐生体腐蚀性能的影响.结果表明:加入Ca可以细化Mg-4Zn合金的动态再结晶晶粒,导致合金中残余第2相的含量增加和尺寸增大,并提高其抗拉强度和屈服强度.其中,Mg-4Zn-0.9Ca合金的抗拉强度和屈服强度分别为300 MPa和278 MPa,比基体合金分别提高了12.4%和68.5%.然而,合金的耐腐蚀性能和剩余抗拉强度随着Ca含量的增加而下降,可归因于合金中残余第2相含量的增加以及尺寸增大.Mg-4Zn合金板材中第2相比较细小、分布均匀,倾向于均匀腐蚀,在0.9%NaCl溶液中浸泡7d的平均腐蚀速率为0.80mg/(cm^2·d),浸泡7d,15d后的剩余抗拉强度分别为217 MPa和205 MPa.

Effects of Ca addition （0.3%, 0.6% and 0.9raass%） on microstructure, mechanical properties and bio-corrosion resistance of the Mg-4Zn based alloys prepared by high strain-rate rolling were investiga- ted by OM,SEM, tensile testing and etc. Ca can refine the dynamic recrystallization grains of the as-rolled alloys, increase the content and the size of the residual second phases, and thus improve the ultimate tensile strength and yield strength. The ultimate tensile strength and the yield strength of Mg-4Zn-0.9Ca are 300MPa and 278MPa respectively, about 12.4 % and 68.5 ~ higher than Mg-4Zn. However, corrosion resist- ance and residual tensile strength decrease with the increasing Ca content, resulting from the higher content and the bigger size of the residual second phases. The bio-corrosion of the Mg-4Zn alloy is uniform since the second phase particles are fine and homogenously distributed. The average corrosion rate immersed in 0.9% NaC1 for 7 days is 0.80 mg/（cm2· d）and the residual tensile strength immersed in 0.9G NaC1 for 7 and 15 days are 217 MPa and 205 MPa,respectively.