Analyzing the compressive behavior of porous Ti6Al4V by X-ray microtomography

Samples with 40% vol. of pores and a pore size distribution between 100 and 500 µm were produced by powder metallurgy from Ti6Al4V alloy powders. Sintering was performed at 1300 °C during one hour in an inert Argon atmosphere in a vertical dilatometer. The compressive strength and the porosity of these samples was investigated before and after compression tests through X-ray microtomography. The values of the elastic modulus (8GPa) and yield strength (80MPa) are within the range of those used in bone implants. Porosity leads to greater deformation whereas fracture of compacts occurs perpendicularly to the applied load. It was determined that the origin of the failure is generated by rupture of interparticle necks and, large pores enhance the propagation of cracks.

本研究采用粉末冶金工艺，以Ti6Al4V合金（Ti6Al4V）粉末为原料，制备了孔隙率为40%体积分数、孔径分布介于100~500 µm的试样。随后在立式膨胀仪中，于1300℃的惰性氩气气氛下保温烧结1小时。通过X射线显微断层成像（X-ray microtomography）技术，分别在压缩试验前后对该类试样的抗压强度与孔隙率进行了表征分析。其弹性模量（8 GPa）与屈服强度（80 MPa）的数值范围，处于骨植入体常用材料的性能区间内。孔隙率的提升会增大试样的变形量，而压坯的断裂方向与施加的载荷方向垂直。经研究确定，试样失效起源于颗粒间烧结颈的断裂，且大尺寸孔隙会促进裂纹的扩展。