Near β-type Zr-Nb-Ti biomedical alloys with high strength and low modulus

The as-cast Zr-12Nb-xTi (x = 0, 2, 4, 8, 16 at.%) alloys were synthesized in a nonconsumable vacuum arc melting furnace. The aim is to explore biomedical materials with excellent mechanical properties for hard tissue replacements. The microstructures were characterized by using optical microscopy (OM) and X-ray diffractometry (XRD), and the mechanical properties were measured by compression tests. The results show that the phase composition of the all samples is composed of beta and omega. The presence of omega phase may be due to the athermal beta -> omega transformation. In the Zr-12Nb-(2-16)Ti alloys, besides of the needle-like structures, a lenticular structure was observed. The grain size decreases firstly and then increases with increasing Ti content. When the Ti concentration is 8%, the grain size reach a minimum about 180-320 mu m. The Zr-12Nb-xTi (x >= 4alloys exhibit relatively higher mechanical properties, especially the Zr-12Nb-8Ti alloy. Its compression strength reaches 1940 MPa and the value of plastic strain is 45.8%. Additionally, the Young's modulus of the Zr-12Nb-xTi alloys ranges from 23 to 27 GPa, which is in range of that of the human skeleton. (C) 2017 Elsevier Ltd. All rights reserved.