Fabrication of porous TiZrNbTa high-entropy alloys/Ti composite with high strength and low Young’s modulus using a novel MgO space holder

Stress shielding is caused by the mismatch of stiffness between bone and implant materials,which may give rise to bone resorption and loosening,thereby causing implantation failure.There is a huge gap between Young’s modulus of human bone and low Young’s modulusβTi alloys.A porous structure design can achieve the target of low Young’s modulus,and thus achieve the matching between human bone and implant materials.However,a suitable space holder(SH)that can be applied at high temperatures and sintering pressure has not been reported.In this study,the TiZrNbTa/Ti titanium matrix composite(TMC)with high strength and large ductility was used as scaffold materials and combined the SH technique with the spark plasma sintering(SPS)technique to obtain a porous structure.A novel space holder,i.e.,MgO particles was adopted,which can withstand high-temperature sintering accompanied by a sintering pressure.The porous TiZrNbTa/Ti with 40 vol.%MgO added exhibits a maximum strength of 345.9±10.4 MPa and Young’s modulus of 24.72±0.20 GPa,respectively.It possesses higher strength compared with human bone and matches Young’s modulus of human bone,which exhibits great potential for clinical application.

满足老幼需求的老旧小区复合型户外活动空间研究——以南京市鼓楼区为例

通过对南京市鼓楼区9个老旧小区的调研,发现导致老年人户外活动频率较低的外在原因主要为:户外环境安全性不足,户外活动空间少且活动空间设计并未考虑到老年人照看儿童的需要。基于老旧小区户外活动空间现状及老幼对活动空间的不同需求,提出了安全性高、空间满足老幼诉求的复合型户外活动空间形式。