Effect Of Adding Nickel On Mechanical And Corrosive Wear Properties Of Titanium-Copper Alloy

Titanium alloy has become an outstanding biomedical metal material due to its low density,high specific strength,non-toxicity,good corrosion resistance and excellent biocompatibility.Titanium-copper alloy has great application potential as a medical implant material.In recent years,numbers of researches about its composition,phase characteristic,antibacterial property and electrocatalytic performance have been carried on deeply.To be a qualified medical implant material applied in more and more broaden fields,its antimicrobial,mechanical and corrosive wear properties need to be comprehensively investigated.On the other hand,Titanium-nickel alloy shows high resilience,even shape memory function.Therefore,this paper adds Ni to the existing alloy Ti₇₀Cu₃₀ with alloying treatment to obtain three kinds of new ternary alloys: Ti₇₀Cu₃₀,Ti₆₅Cu₃₀Ni₅ and Ti₆₀Cu₃₀Ni₁₀.The microstructure and composition of these alloys were characterized by X-ray diffractometer and glow discharge optical emission spectrometry;their nano-mechanical properties were studied by nano-indentation hardness tester;electrochemical method was used to study the electrochemical behaviors in artificial body fluid;then the wear properties were investigated using ball-disk friction and wear tester.The results are as follows:1.The phase structure and composition of three alloys were analyzed.Ti₇₀Cu₃₀ is mainly composed of CuTi and CuTi₃ phase.After adding Ni,Ti₆₅Cu₃₀Ni₅ mainly consists of Cu NiTi₂ and TiNi_0.8Cu_0.2 phase,and Ti₆₀Cu₃₀Ni₁₀ has new phases: CuNi_0.5Ti_0.5O₂ and CuNi₂ Ti.The compositional distribution curve shows that the maximum atomic percentages of Ti,Cu and Ni content are almost the same as the alloying ratio.2.The nano-mechanical properties of Ti₇₀Cu₃₀,Ti₆₅Cu₃₀Ni₅ and Ti₆₀Cu₃₀Ni₁₀ were studied by nanoindentation technique.The experimental results show that the addition of nickel improves the hardness of Ti₇₀Cu₃₀ alloy and its ability to resist external load.The alloy with a content of nickel at 5 at.% has better elastic deformation ability,but the content of nickel at 10 at.% decreases its elastic modulus.The elastic modulus of three alloys is in order as: Ti₆₅Cu₃₀Ni₅ > Ti₇₀Cu₃₀ > Ti₆₀Cu₃₀Ni₁₀.3.The electrochemical corrosion behaviors of the alloys in Hank’s simulated body fluid were studied by means of potentiodynamic polarization curve method and impedance spectrogram method.The experimental results show that addition of nickel reduces the corrosion resistance of Ti₇₀Cu₃₀ alloy.When the content of nickel reaches up to 10 at.%,severe corrosion takes place in the artificial body fluid,with the occurrence of large-scale pitting.Finally,the structure of Ti₆₀Cu₃₀Ni₁₀ is destroyed.4.The friction/wear properties and their mechanisms were studied by friction and wear tester.Dry friction results show that the wear in air is adhesiondominated.The wear resistance of Ti₆₅Cu₃₀Ni₅ is the best,and that of Ti₆₀Cu₃₀Ni₁₀ is the worst.In the wet friction in artificial body fluid,the wear mechanism is different for the impact of electrochemical corrosion: Ti₆₀Cu₃₀Ni₁₀ is mainly dominated by chemical corrosion wear,while Ti₇₀Cu₃₀ presents abrasive wear,and Ti₆₅Cu₃₀Ni₅ falls in between.This also leads to the highest resistance performance of Ti₆₅Cu₃₀Ni₅.