• Corrosion Science and Technology
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• 제8권4호
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• pp.139-142
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• 2009

Recently, quaternary titanium alloys of the system Ti-Nb-Ta-Zr received considerable research interest as potential implant materials because of their excellent mechanical properties and biocompatibility. However, only few reported works were available on the corrosion behavior of such alloys. Hence, in the present work, electrochemical corrosion of Ti-35Nb-5Ta-7Zr alloy, which has been fabricated by arc melting and heat treatment, was studied in 0.9 wt% NaCl at $37\pm1^{\circ}C$, along with biomedical grade Ti-6Al-4V and CP-Ti. The phase and microstructure of the alloys were investigated employing XRD and SEM. The results of electrochemical studies indicated that the corrosion resistance of the quaternary alloy was inferior to that of Ti-6Al-4V and CP Ti.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.177-180
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• 2002

The effects of pressing temperatures on the formability and the microstructural evolution during equal channel angular pressing (ECAP) of lamellar Ti-6Al-4V alloy were investigated in this study. ECAP above isothermally 600$^{\circ}C$ was successful without producing any noticeable segments at the specimen surfaces after a single pass of pressing. After 4 passes of ECA pressing, lamellar microstructures were significantly refined revealing equiaxed grains of 0.3$\mu\textrm{m}$ in diameter consisting of high angle grain boundaries. Also these ultrafine grains were relatively stable with little grain growth when annealed up to 600$^{\circ}C$ for 1hour.

• 한국재료학회지
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• 제9권7호
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• pp.688-694
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• 1999

Ti-6Al-4V 합금을 타겟트로 사용하여 유리 기판위에 dc reactive magnetron sputtering법으로 $N_2$/(Ar+N_2)$ 비, 기전력 및 시간등의 여러 가지 증착 조건에서 Ti-6Al-4V-N 필름을 증착하였고, 각각의 증착 조건에 따른 결정구조 및 우선방위 거동은 X-선 회절장치를 사용하여 조사하였다. Ti-6Al-4V-N 필름은 본질적으로 fcc 결정구조의 $\delta$-TiN에 Al과 V이 결함으로서 고용된 변형된 형태의 $\delta$-TiN구조이고, TiN의 격자상수(4.240 )보다 작은 값을 나타내었는데, 이는 Ti(1.47 )에 비하여 상대적으로 원자반경이 작은 Al(1.43 )과 V (1.32 )이 Ti의 격자위치에 치환된 결과이다. 그리고 Ti-6Al-4V-N 필름은 $_N2$가스 분압이 감소됨에 따라 (111) 우선방위 성장거동을 하였을 뿐만아니라 증착시간의 증가에 따라 뚜렷한 (111) 우선방위 성장거동을 나타내었다. 그리고 증착속도 및 결정입도의 거동 또한 여러 가지 증착 조건에 크게 의존한다

• 소성∙가공
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• 제16권4호
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• pp.223-228
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• 2007

The profile ring rolling process of Ti-6Al-4V alloy was investigated by finite element(FE) simulation and experimental analysis. The process design of the profile ring rolling includes geometry design and optimization of process variables. The geometry design such as initial billet and blank sizes, and final rolled ring shape was carried out with the calculation method based on the uniform deformation concept between the wall thickness and ring height. FEM simulation was used to calculate the state variables such as strain, strain rate and temperature and to predict the formation of forming defects during ring rolling process. Finally, the mechanical properties of profiled Ti-6Al-4V alloy ring product were analyzed with the evolution of microstructures during the ring rolling process.

• 한국기계가공학회지
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• 제18권11호
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• pp.76-82
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• 2019

This study aims to find the shapes of an end-mill with low cutting temperature during the end-mill process of Ti-6Al-4V alloy. Such ${\alpha}-{\beta}$ titanium alloys are increasingly more used for their high tensile strength and high corrosion resistance. The cutting characteristics of Ti-6Al-4V alloy were studied using an analytical method validated by comparing the estimated cutting resistance with that from experiments. The end-mill shape was analyzed using an experimental method. The end-mill shape with low cutting resistance and low cutting temperature was confirmed by analyzing the signal-to-noise ratios for various conditions. Then, the factors with significance factor of 95% or more were determined in the variance analysis. Finally, an end-mill shape that can ensure a low cutting temperature was proposed.

• 대한치과보철학회지
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• 제36권5호
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• pp.701-720
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• 1998

Research advances in dental implantology have led to the development of several different types of materials and it is anticipated that continued research will lead to advanced dental implant materials. Currently used pure titanium has relatively low hardness and strength which may limit its ability to resist functional loads as a dental implant. Ti-6Al-4V also has potential problems such as corrosion resistance. osseointegration properties and neurologic disorder due to aluminium and vanadium, known as highly toxic elements, contained in Ti-6Al-4V. Newly developed titanium based alloys(Ti-20Zr-3Nb-3Ta-0.2Pd-1In, Ti-20Zr-3Nb-3Ta-0.2Pd) which do not contain toxic metallic components were designed by the Korea Institute of Science and Technology (KIST) with alloy design techniques using Zr, Nb, Ta, Pd, and In which are known as non-toxic elements. Biocompatibility and osseointegration properties of these newly designed alloys were evaluated after implantation in rabbit femur for 3 months. The conclusions were as follows : 1. Mechanical properties of the new designed Ti based alloys(Ti-20Zr-3Nb-3Ta-0.2Pd-1In, Ti-20Zr-3Nb-3Ta-0.2Pd) demonstrated close hardness and tensile strength values to Ti-6Al-4V. 2. New desinged experimental alloys showed stable corrosion resistance similar to the pure Ti but better than Ti-6Al-4V. However, the corrosion rate was higher for the new alloys. 3. Cell culture test showed that the new alloys have similar cell response compared with pure Ti and Ti-6Al-4V with no cell adverse reaction. 4. New designed alloys showed similar bone-metal contact ratio and osseointegration properties compared to pure Ti and Ti-6Al-4V after 3 months implantation in rabbit femur. 5. Four different surface treatments of the metals did not show any statistical difference of the cell growth and bone-metal contact ratio.

• 소성∙가공
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• 제15권2호
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• pp.105-111
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• 2006

A study was made to investigate the microstructure and the mechanical properties of low-carbon steel, Al-Mg alloy and Ti-6Al-4V alloy each representing bcc, fcc and hcp crystal structures, respectively fabricated by equal-channel angular(ECA) pressing. After a series of ECA pressings was performed, most grains were significantly refined below ${\mu}m$ in diameter with high mis-orientation of grain boundaries irrespective of different crystal structure used. Regarding the strain hardening capability, tensile tests of ultrafine grain (UFG) dual-phase (ferrite/martensite) steel which was different from UFG ferrite-pearlite steel were carried out at ambient temperature, and corresponding mechanical properties were discussed in relation to modified C-J analysis. Low-temperature and/or high strain-rate superplasticity of the UFG Al-Mg alloy and UFG Ti-6Al-4V alloy were also studied. Based on the analysis used in this study, it was concluded that UFG alloys exhibited the enhanced mechanical properties as compared to coarse-grained (CG) counterparts.

• Corrosion Science and Technology
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• 제20권6호
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• pp.475-483
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• 2021

Additively manufactured titanium alloy is one of the promising materials in advanced medical industries. However, these additively manufactured alloys show corrosion properties different from those of conventional materials due to their unique microstructure. In this study, the effect of surface roughness and masking conditions on the results of the potentiodynamic polarization tests on additively manufactured or conventional Ti-6Al-4V alloys in artificial saliva solution with or without fluoride was investigated. The results showed that the corrosion potential was slightly lower with a flat cell with an O-ring than with masking tape. The corrosion rate was decreased with decreases in the surface roughness. Localized corrosion involving delamination of the surface layer occurred at 7 ~ 9 V (SSC) on the additively manufactured alloy in solution with or without fluoride when the samples were finished with 1000-grit SiC paper, whereas localized corrosion was not observed in the specimens finished with 1-㎛ alumina paste.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 추계학술발표 개요집
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• pp.160-162
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• 1997

• 한국재료학회:학술대회논문집
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• 한국재료학회 1993년도 추계 학술발표 강연 및 논문 개요집
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• pp.15-15
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• 1993