| Since the middle of the 20th century, titanium and titanium-based Biomedical Material have been widely used in human disfunctioned hard tissue replacement., and also it has been made a great progress in subsequent development and application,improving the quality of people’s life greatly. Biomedical Titanium has become the first choice of human medical implants material due to its great intensity, low elastic modulus, high strength, excellent biocompatibility and corrosion resistance.The research on this subject is with the aid of a cluster model theory, using the CN14 cluster model represents a component formula of β-titanium with body-centered cubic structure, Under the constraints of the electron concentration e/a = 4.17,according to the size of Enthalpy of mixing △H that between alloying elements in cluster(△H for intracluster characterize the size of interaction force between atoms.The more negative the △H is,the larger the mutual attraction will be.The more positive the AH is, the greater the mutual repulsion will be),we can determine the "clusters+connector atom" model [SnTi14] Mb3 which using Sn as the center atom,Ti as the shell atom,Nb as the connection atom.The ingredients is smelted into button-like alloy whose diameter is 30mm and height is 10mm.Detect the alloy through component analysis, optical microscopy, XRD detector test and nanoindentation testing and the other test method.The experiment is divided into three stages:The first phase is to use Zr atom substituted with the central atom Sn, the actual expression of cluster is [(Sn1-xTix) (Ti14-xZrx)] Nb3 (x= 0,0.3,0.5,0.7); in the second stage,reduct the content of Sn gratually on the basis of [SnTi14] Nb3, we can get the clusters formula of [Sn1-xTi14+x] Nb3 (x= 0,0.1,0.2,0.3,0.4); the third stage is base on the content reduction of the ternary alloys in the second phase and then add Zr atoms to replace Ti atoms which on the cluster shell,the formula of conpoment is[(SnxTi1-x)(Ti14-yZrY)] Nb3 (X is determined by ternary alloy, Y= 0.2,0.4,0.6,0.8)Experiments verified the feasibility of the cluster model’s application in the titanium alloy and proved that there is a certain link between cluster structure and alloy phase structure. With the intracluster mixing enthalpy decrease, Pphase stability of titanium also decrease and alloy phase transits from a to p.In the three stage test, the elastic modulus (65.6 GPa) and hardness (959.3HV) of the ternary alloy [Sn0.8Ti14.2] Nb3 is at the lowest value,at the same time,the alloy is composed of ’β+β’phase.In the series alloys of adding element Zr which on the basis of the ternary alloys, with the increase of Zr atoms, elastic modulus increases gratually. adding Zr atoms increased β alloys phase stable capability, Zr element at this time is no longer a neutral element, but as β stabilizing element,What’s more,the lattice parameter and the hardness of the alloy are also increase. |
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