Biocorrosion Behavior And Antibacterial Properties Of TiNiCu Alloys Treated By Different Processing

In the process of clinical application,there were many problems,such as bacterial infection and the biosafety caused by the accelerated dissolution of metal ions due to the exisitence of bacteria.In the present paper,Ti_49.2Ni_43.8Cu₇ alloy was used as the research object,which was treated by high pressure torsion,thermal oxidation and N ion implantation respectively.The biocorrosion behavior and antibacterial properties of Ti Ni Cu alloys under these different treatment processes were systematically studied.The relationship between microstructure and surface composition of Ti Ni Cu alloy and its biocorrosion and antibacterial properties was established.The biocorrosion mechanism and antibacterial mechanism of Ti Ni Cu alloy under different processes were revealed.The results showed that Ti Ni Cu alloy with high pressure torsion consisted of B2 phase and Ti₂（Ni,Cu）phase at room temperature.When high pressure torsin process reached 1/2 T,the alloy showed coarse grained structure.At the same time,the dislocation density was increased and the dislocation cell structure was formed.When the alloy was twisted for one turn,the microstructure was composed of coarse grain structure,submicron grain and dislocation cell structure,and the microstructure uniformity was poor.The amorphous degree of the dislocation intracellular tissue was increased.When the turns reached 3/2 T,the grain size of the alloy was about 20 nm.There were a lot of amorphous structure in the alloy and part of the microstructure was changed from austenite to martensite.The Ti Ni Cu alloys with1/2 and 3/2 turns of high pressure torsion showed excellent biological corrosion property,and their antibacterial properties were better than the coarse-grain Ti Ni Cu alloy.After thermal oxidation treatment,Ti Ni Cu alloy was consisted of B2 phase,Ti₂（Ni,Cu）phase,Ti O phase and Ti O₂ phase at room temperature.The oxide particles were formed on the surface of the alloy,and Cu element was enriched on the oxide particles.The biological corrosion property of hot-oxidized Ti Ni Cu alloy was decreased,and the antibacterial rate was increased by 8.7%compared with the coarse-grained alloy.After N ion implantation,Ti Ni Cu alloy was consisted of B2 phase,Ti₂（Ni,Cu）phase,Ti N phase and Ti₂N phase at room temperature.After N ion implantation for 5 h,granular bulge structure was formed on the surface of the alloy.The pore structure appeared on the surface of the alloy after N ion implantation for more than 10 h,and the pore diameter gradually increased with the prolonging of N ion implantation time.When N ion implantation time was less than 15 h,the biological corrosion properties of Ti Ni Cu alloy were better than the original alloy.The antibacterial rate of Ti Ni Cu alloy implanted with N ions for 15 h was the highest,which was 26.6%higher than the original alloy.