http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
기계적 합금화법에 의해 제조된 Al+Al3Ti합금 및 Al+10wt.%Ti합금의 고용현상
김혜성,이정일,김긍호,금동화,서동수( Hye Sung Kim,Jung Ill Lee,Gyeung Ho Kim,Dong Wha Kum,Dong Soo Shur ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.2
The solubility of Ti in Al matrix was determined by X-ray diffraction method on two different mechanical alloying systems, i.e Al+Al₃Ti and Al+Ti alloys. Starting powder compositions of two systems were chosen for final volume fraction of Al₃Ti phase being 25%. The solubility of Ti in α-Al was estimated by the lattice parameter measurement of Al. For Al+Al₃Ti mixture, it appeared that some of Al₃Ti particles decomposed during milling and maximum solubility of Ti in A1 was about 0.99%. The majority of Al₃Ti particles were dispersed uniformly in Al matrix, having approximate size of 100∼200㎚. On the other hand, higher Ti solubility of 1.24 wt.% was found in Al+Ti system, with starting composition of Al+10 wt.%Ti. After 15 hours of milling, Ti phase was identified as 20㎚ sized particles embedded in Al matrix. The annealing of mechanically alloyed powders from Al+Al₃Ti and Al+10 wt.%Ti systems was followed in the temperature range of 200 to 600℃ to study thermal stability of supersaturated solution of Al(Ti). After annealing, the lattice parameter of A1 reverted back to that of pure Al, and the peak intensity ratio of Al₃Ti/Al was increased more than the original value before annealing. These results suggest that Ti dissolve into alpha-Al solutions during milling, and by annealing, Do_(22)-Al₃Ti phase forms from Al(Ti) solution.
기계적 합금화법으로 제조된 과포정 Al-Ti합금에서 Al3Ti 형성에 관한 연구
김혜성,서동수,김긍호,금동화 ( Hye Sung Kim,Dong Soo Suhr,Gyeung Ho Kim,Dong Wha Kum ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.1
Mechanical alloying is an effective process to finely distribute inert dispersoids in an Al-TM(TM is a transition metal) system. It has been considered that high melting point aluminides are formed by precipitation from supersaturated Al(Ti) powder. This analysis is based on the fact that much higher content of TM than the solubioity can be dissolved in alpha aluminum during the high energy ball milling. Thus, decomposition behavior of Ti in the Al(Ti) was considered very important. But it is confirmed that the higher portion of Ti than Al(Ti) solid solution is existed as nano-sized Ti particles in the MA powders by high energy ball nilling from the XRD spectrum and TEM analysis in this study. Therefore, the role of undissolved TM particles affect the formation of aluminides should be suitably considered. In this study, we present experimental observation on the formation of Al₃Ti fron mechanical alloyed Al-Ti alloys in the hyperperitectic region. This study showed that, in the mechanically alloyed Al-20wt%Ti specimen, intermediate phase of cubic Al₃Ti and tetragonal Al_(24)Ti_8 formed at 300∼400℃ and 400∼500℃, respectively, before the MA state reaches to equilibrium at higher temperatures. The formation behavior of Ll₂-Al₃Ti is interpreted by interdiffusion of A1 and Ti in solid state based on the fact that large amount of nano-sized Ti particles exist in the milled powder. Present analysis indicated undissolved Ti particles of nanosize should have played an important role initiation the formation of Al₃Ti phase during annealing.
김용성,김혜성,이덕열,금동화,이준엽,김정구,구세진 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.4
The performance of magnesium sacrificial anodes was evaluated to improve the efficiency of anodes based on Mg-Mn, Mg-Al and Mg-Al-Zn alloys. Potentiodynamic polarization, galvanostatic-weight loss tests, EPMA and XRD analyses were used to investigate the corrosion rate, driving potential, efficiency, microstructure. Polarization results indicated that the alloying with Mn, Al, Zn reduced the corrosion rates of Mg anodes. Corrosion morphology was changed from localized to uniform attack by the alloying. Addition of Mn to the Mg anodes yielded increased driving potential and efficiency. The efficiency of Mg-Al anodes was improved up to the 6.37wt% Al addition. The addition of Zn had a little effect on the efficiency of Mg-Al-Zn anodes. Mg-Mn anodes produced higher efficiency in the T6 heat treatment than in the as-cast condition. The improvement of efficiency on Mg-Mn anodes by heat treatment was related to the redissolution of Mg₂Si and Fe-Mn particles.
RSP Al-1.2-7wt% Ti 합금의 고온인장변형특성
김혜성,금동화 대한금속재료학회(대한금속학회) 1994 대한금속·재료학회지 Vol.32 No.2
The P/M consolidation of the rapidly solidified powders is an effective way to produce very fine microstructure in the hyper-peritectic Al-Ti alloys, where the grain size is less than a few microns in diameter with fine and uniform dispersion of the Al₃Ti particles. The RSP Al-Ti alloys show good high temperature strength above 300℃ mainly due to excellant thermal stability of the aluminide. In order to investigate the deformation behavior of the Al-Ti alloy at high temperatures, fine-grained Al-1.2wt%Ti, Al-3.6wt%Ti and Al-7wt%Ti specimens were produced through hot extrusion of the rapidly solidified powders made by gas atomization. The strain-rate(ε˚) vs. flow stress(σ) relations were obtained by the strain-rate change tests in tension at 300-500℃. It has been analysed that the deformation behavior could be represented by the (ε˚/D)=A·exp[-Q_a/(RT)]·(σ/E)^n where D and E are diffusivity and elastic modulus of pure Al, respectively. Stress exponent, n, was 8.5, and the activation energy for deformation was 163∼183kJ/㏖. this observation indicates that tensile deformation of the fine-grained RSP Al-Ti alloys is governed by dislocation slip activated by lattice diffusion of aluminum. Even though the grain size is very fine, the fine dispersion of Al₃Ti particles prevents grain boundaries from being activated at the high temperature range investigated.