Study On Corrosion Characteristics And Corrosion Resistance Mechanism Of New Titanium-zirconium Alloy

Because of their advantages of high specific strength,excellent corrosion resistance,high fatigue strength and heat resistance,titanium-zirconium alloys have been widely used in aerospace,naval,medical,petrochemical and other fields.They play a very important role in ensuring the safety of workpieces,reducing the weight of the parts,optimizing the strength of the parts and prolonging the life of the parts.B is a stable element,and a large number of literatures have shown that adding B to the titanium alloy will result in the formation of TiB or TiB₂,resulting in the reduction of the grain size to improve effectively the mechanical properties of the material.However,the effect of boron addition on the corrosion resistance of titanium-zirconium alloy is not clear.Therefore,on the basis of the improvement of the mechanical properties of the Ti-30Zr-5Al-3V alloy,the influence of the addition of boron on the corrosion resistance of the Ti-30Zr-5Al-3V alloys and their corrosion mechanism are investigated.The ingots of Ti-30Zr-5Al-3V-xB alloys are got by non-consumable vacuum melting furnace,and the hot-rolled alloys are got by rolling under 850?.The phase composition,corrosion resistance and their principle of the alloy are studied.The alloys added B are formed by?phase,?phase and TiB phase.As the mass fraction of B continue to increase,the size of?lath diminishes and the the grain refinement occurs.The electrochemical corrosion measurements show similar results in3.5%NaCl and 5%HCl solutions.With the increase of B content,the corrosion potential of Ti-30Zr-5Al-3V-xB alloys reduces and the corrosion current density raises.The result of electrochemical impedance spectroscopy shows the diameter of arc diminishes,and the phase angle and impedance mode of the alloys added B are lower than that of 0B alloy.The conclusions explain that the corrosion resistance of the alloy decreases when the boron is added.XPS spectra shows that the passivation films of the alloys are basically comprised of TiO₂,ZrO₂,Al₂O₃.With the increase of B content,in 3.5%NaCl solution and in 5%HCl solution,the average surface roughness Ra of alloy increases from 5.0±0.5nm to 9.0±0.3 nm and 7.4±1.0nm to 16.9±1.2 nm,respectively.The results of immersion test are the same as those of electrochemical test.0B alloy has the smallest corrosion rate and the best corrosion resistance.