Effect Of Zr,Si Contents On Microstructure And Properties Of β-type Ti-12Mo Alloys

β titanium alloys which contain non-toxic elements, have good biocompacity,lower elastic modulus and superior wear and corrosion resistance, are ideal andpromising biomaterials in the future. In this work, Ti-12Mo-xZr(x=0,2,4,7,10wt%) and Ti-12Mo-xSi(x=0,0.5,1.0,1.5,2.0wt%) alloys were fabricated byusing tungsten electrode arc furnace and LZ5type centrifugal castingtechnique.The alloys’ microstructures were observed and characterized.Themicrohardness and compression performance of the alloys were tested.The frictionand wear performance of Ti-12Mo-xZr and Ti-12Mo-xSi alloys grindingrespectively against TA2and TC4under the lubrication of Hank’s solution wasinvestigated.The electrochemical corrosion characteristics and mechanism of thealloys in three different solutions such as0.9%NaCl solution,Ringer’s solution andHank’s solution were studied with three-electrode cell.The research results showed that the microstructures of Ti-12Mo-xZr andTi-12Mo-xSi alloys are composed of a single equiaxial β phase, and with theincrease of Zr and Si elements content the crystal grains are refined.Themicrohardness values of Ti-12Mo-xZr and Ti-12Mo-xSi alloys are respectively348~384HV and438~473HV, so Ti-12Mo-xZr and Ti-12Mo-xSi alloys have highermicrohardness than pure Ti and Ti-6Al-4V alloy.Ti-12Mo-xZr alloy exhibits higherplasticity in the compression process, and the compression elastic modulus isbetween18.60~19.01GPa. Athough Ti-12Mo-xSi alloy has poorer ductility thanTi-12Mo-xZr alloy, its fracture behavior is ductile fracture, and the compressionelastic modulus is between21.62~22.25GPa.From the point of view of the abrasion loss, with the increase of Zr elementcontent, the wear rate of Ti-12Mo-xZr alloy decreases, and wear resistanceincreases; with the increase of Si element content, the wear rate of Ti-12Mo-xSialloy increases, and abrasion resistance decreases.From the point of view offriction coefficient, Zr and Si elements content have little effect on the frictioncoefficient of Ti-12Mo-xZr alloy and Ti-12Mo-xSi alloy. The friction coefficientof Ti-12Mo-xZr alloy is between0.13and0.36,and that of Ti-12Mo-xSi alloy is0.17~0.4.When grinding against TA2, the wear mechanism of Ti-12Mo-xZr alloyand Ti-12Mo-xSi alloy is mainly adhesive wear, accompanied by abrasive wear;while against TC4the wear mechanism is abrasive wear.As for Ti-12Mo-xZr alloys, in0.9%NaCl solution, Ti-12Mo-7Zr alloy has thehighest self-corrosion potential-0.047V;in Ringer’s solution, Ti-12Mo alloy shows the highest self-corrosion potential-0.319V and in Hank’s solution Ti-12Mo-2Zralloy puts up the highest self-corrosion potential-0.410V.When it comes toTi-12Mo-xSi alloys, Ti-12Mo alloy exhibits the highest self-corrosion potential-0.206V in0.9%NaCl solution; in Ringer’s solution Ti-12Mo-1Si alloy shows thehighest self-corrosion potential-0.304V and in Hank’s solution Ti-12Mo-0.5Sialloy has the highest self-corrosion potential-0.371V.The corrosion tendency ofTi-12Mo-xZr and Ti-12Mo-xSi alloys in0.9%NaCl solution is the smallest, and inHank’s solution is the largest.The corrosion form of the alloys is pittingcorrosion.The passivation membrane whose composition contains MoO3, ZrO2,SiO2and TiO2forming in alloy corrosion surface, is protective to the alloys, soTi-12Mo-xZr and Ti-12Mo-xSi alloys have good corrosion resistence.