Jenei Péter, Choi Hyelim, Tóth Adrián, Choe Heeman, Gubicza Jenő
Department of Materials Physics, Eötvös Loránd University, P.O.B. 32, Budapest H-1518, Hungary.
School of Advanced Materials Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Republic of Korea.
J Mech Behav Biomed Mater. 2016 Oct;63:407-416. doi: 10.1016/j.jmbbm.2016.07.012. Epub 2016 Jul 15.
Pure Ti and Ti-5%W foams were prepared via freeze casting. The porosity and grain size of both the materials were 32-33% and 15-17µm, respectively. The mechanical behavior of the foams was investigated by uniaxial compression up to a plastic strain of ~0.26. The Young׳s moduli of both foams were ~23GPa, which was in good agreement with the value expected from their porosity. The Young׳s moduli of the foams were similar to the elastic modulus of cortical bones, thereby eliminating the osteoporosis-causing stress-shielding effect. The addition of W increased the yield strength from ~196MPa to ~235MPa. The microstructure evolution in the grains during compression was studied using electron backscatter diffraction (EBSD) and X-ray line profile analysis (XLPA). After compression up to a plastic strain of ~0.26, the average dislocation densities increased to ~3.4×10(14)m(-2) and ~5.9×10(14)m(-2) in the Ti and Ti-W foams, respectively. The higher dislocation density in the Ti-W foam can be attributed to the pinning effect of the solute tungsten atoms on dislocations. The experimentally measured yield strength was in good agreement with the strength calculated from the dislocation density and porosity. This study demonstrated that the addition of W to Ti foam is beneficial for biomedical applications, because the compressive yield strength increased while its Young׳s modulus remained similar to that of cortical bones.
通过冷冻铸造制备了纯钛泡沫和含5%钨的钛泡沫。两种材料的孔隙率和晶粒尺寸分别为32 - 33%和15 - 17μm。通过单轴压缩对泡沫材料的力学行为进行了研究，直至塑性应变为0.26。两种泡沫的杨氏模量均为23GPa，这与根据其孔隙率预期的值非常吻合。泡沫的杨氏模量与皮质骨的弹性模量相似，从而消除了导致骨质疏松的应力屏蔽效应。添加钨使屈服强度从196MPa提高到235MPa。使用电子背散射衍射（EBSD）和X射线线形轮廓分析（XLPA）研究了压缩过程中晶粒内的微观结构演变。在压缩至塑性应变为0.26后，钛泡沫和含钨钛泡沫中的平均位错密度分别增加到3.4×10(14)m(-2)和~5.9×10(14)m(-2)。含钨钛泡沫中较高的位错密度可归因于溶质钨原子对位错的钉扎效应。实验测量的屈服强度与根据位错密度和孔隙率计算出的强度非常吻合。这项研究表明，在钛泡沫中添加钨对生物医学应用有益，因为压缩屈服强度增加，而其杨氏模量仍与皮质骨的杨氏模量相似。
