Strengthening mechanisms of developed biomedical titanium alloys with ultra-high ratio of yield strength to Young's modulus
Ruishi Yin, Jinzhou Gong, Pengyao Li, Yujian Zhang, Junsong Zhang, Shunxing Liang, Xinyu Zhang
Abstract
The key factor for the safe and long-term application of biomedical implants in hard tissues is the large ratio of yield strength to Young's modulus . The development of titanium alloys possessing a large ratio of yield strength to Young's modulus has been an enduring challenge in biomedical hard tissue implant materials . In this work, an approach that combines grain refining and controlling the fraction of deformed grains was proposed to increase the yield strength of metastable β bio - Ti alloys with low modulus. Taking titanium-zirconium alloy as the research object, a low modulus TiZrNbSnMo alloy system was designed and prepared by controlling the content of β-stabilizer molybdenum (Mo) and performing appropriate thermomechanical deformation to control the recrystallization process. This biomedical titanium-zirconium alloy system achieves a breakthrough for bio-Ti alloys by exhibiting an ultra-high yield strength of 816 MPa while maintaining an ultra-low Young's modulus of 42 GPa. Surprisingly, the ratio of yield strength to Young's modulus (Re/E) of the Ti-5Zr-10Nb-4Sn-3Mo alloy is as high as about 1.36 × 10 −2 , which far exceeds that of existing titanium alloys . Apart from high yield strength and ultra-low Young’s modulus, this alloy system also shows a high ultimate tensile strength over 850 MPa and an excellent elongation of 30 %. The above alloy design ideas provide new insights into the relationship between Young's modulus and yield strength of biomedical alloys, and also provide a better choice for biological implant materials.