Dynamic Young's modulus of open-porosity titanium measured by the electromagnetic acoustic resonance method

As biological implants, porous titanium with adjustable mechanical properties can solve the stress-shielding effect. In this paper, porous titanium was prepared by the powder metallurgy method, where urea powders as the second phase were removed by heat treatment. Pore morphology (such as pore size and character) was controlled by the character of urea powders. The dynamic Young's moduli of such porous titanium with different morphology was measured by the electromagnetic acoustic resonance method. From the semi-log plots of Young's modulus versus the porosity, it was found that with increased porosity this modulus firstly decreases linearly, then decreases rapidly and goes to zero at certain porosity. However, the Young's modulus was independent of pore size. The relationship between Young's modulus and the porosity was explained by a parallel model based on the Minimum Solid Area method. The value of linear slop `b' and the percolation limit `PC' were used for predicting the trend of Young's modulus varied with the porosity and pore size. So porous titanium with appropriate Young's modulus can be chosen as a candidate for bone substitutes.