摘要
Zn-1.0Cu-0.5Ca(TA15)alloy has shown promising characteristics of enhanced mechanical properties and biodegradability for absorbable cardiovascular stents,endovascular devices,and wound closure devices applications.In this study,the TA15 alloy for bioabsorbable biomedical applications is investigated.In the conventionally cast TA15(TA15-C)alloy,CaZn_(13) phase are present as a large dendritic network with an average size of 73.25±112.84μm,Hot rolling of the TA15-C alloy has broken the long and dendritic network of the CaZn_(13) phases,however,the refined phases are observed as segregations and the distribution is non-uniform.These segregated CaZn_(13) suffered heavy localised corrosion which lead to poor mechanical properties in the as-fabricated condition and after biodegradation.Ultrasonic treatment(UST)during casting is identified as an effective technique for the refinement and redistribution of CaZn_(13) particles in TA15 alloy,which successfully reduce the size of the CaZn_(13) phase to 10.91±4.65μm in the as-solidified condition.After hot rolling,the UST processed TA15(TA15-UST)shows improved mechanical properties due to grain refinement and the reduction in microstructural defects,i.e.the broken CaZn_(13) phase.Results of 8-week immersion corrosion tests showed that both alloys possess very similar corrosion rate.However,TA15-UST has markedly improved corrosion homogeneity compared to TA15-N which favours the retention of mechanical properties even after prolonged exposure to physiological fluids.
基金
support of the Australian Research Council through the ARC Research Hub for Advanced Manufacturing of Medical Devices(IH150100024)。
