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Ti-Ni-Cu 합금의 B2??B19 변태에 수반되는 형상기억특성과 격자변형과의 관계
남태현 慶尙大學校生産技術硏究所 1991 生産技術硏究所論文集 Vol.7 No.-
Lattice deformation associated with the B2?? B19 transformation in Ti-Ni-Cu shape memory alloys have been calculated by using lattice parameters of the parent and martensite phases obtained from X-ray diffraction. The transformation elongaton and hysteresis associated with the B2?? B19 transformation were examined in relation to the calculated lattice deformation, and the following was found. Cu-content dependence of the transformation elongaton originates from that of the lattice deformation. The decrease in transformation hysteresis with increasing Cu-content originates from the decrease in the normal component of the lattice deformation.
南泰鉉,崔普永,李于錫,蔡義業 경북대학교 의학연구소 1969 慶北醫大誌 Vol.10 No.1
Electrocardiographic changes of 15 rabbits under acute hypoxia, chronic hypoxia and G-force )+Gz) were studied. 3 standard limb leads and 3 augmented limb leads were recored. Acute hypoxia was induced exposing animals to low pressure chamber at the 18,000ft. equivalent altutude and 1/2 atmospheric pressure was maintained in the the chamber. Another acute hypoxia was demonstrated with rebreathing methods. Chronic hypoxia was obtained with exposing animals for 7hrs.per day and for 7 weeks. ECG changes were also measured at each combination of magnitude of G and exposure time as following three different runs with 27G-2min, 18 G-2 min, and 10 G-5 min. Under acute hypoxia exposing to low pressure chamber increased heart rate, decreased amplitude of P and T waves, shortened Q-T intervlas and sinus tarchycardia were noted. In another acute hypoxia induced by rebreathing methods, increased R_2 waves and peaked T_2 were observed. Under positive acceleration increased amplitude of T_2, peaked T_2 flat P_2 were specific ECG findings of exhausted heart. In first recovery stage from dangerous G stress, QRS-complex of ECG was reappeared regularly and small P AND T was appeared thereafter.
Ti 과잉 Ti-Ni-Cu 합금박막의 상변태거동 및 형상기억특성
남태현,박중학 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.6
Thin films of 55Ti-(45-x)Ni-xCu(x = 0, 5, 10, 20 at.%) compositions were fabricated by d.c. magnetron sputtering method. Deposited films were annealed at 973 K for 3.6 ks to induce crystallization. The phase transformation behaviors of these thin films were investigated by differential scanning calorimetry and X-ray diffraction. Shape memory characteristics were studied by thermal cycling test under a constant load. As-sputtered films contained a mixture of amorphous and very fine(=15 ㎚) Ti₂Ni phase. Crystallization temperature(Tc) decreases from 774 K to 747 K with increasing Cu-content from 0 at.% to 20 at.%. Two-stage transformation behavior, i.e., the B2→R→B19', was observed in a 55Ti-45Ni(at.%) alloy thin film. The B2→B19' transformation occurred in a 55Ti-40Ni-5Cu(at.%) alloy film, while the B2→B19 transformation occurred in 55Ti-35Ni-l0Cu(at.%) and 55Ti-30Ni-20Cu(at.%) alloy films. The stress dependence of transformation temperature(dT/dσ) of 55Ti-40Ni-5Cu(at.%) and 55Ti-35Ni-10Cu(at.%) thin films were 0.015 K/㎫ and 0.016 K/㎫, respectively. They were very small as compared to those of 50Ti-45Ni-5Cu(at.%) and 50Ti-40Ni-10Cu(at.%) alloys.
남태현 국립경상대학교 공과대학 부설 첨단소재연구소 1993 尖端素材 Vol.3 No.-
Transformation temperatures and shape memory effect of Ti-Ni-Cu-Fe shape memory alloys have been investigated by means of electrical resistivity measurements, X-ray diffraction and thermal cycling tests under constant load, and then compared with those of Ti-Ni-Cu alloys. Transformation temperature decreases largely with increasing Fe content, while the transformation behaviour does not change (B2-B19-B19'). The critical stress for slip deformation increases largely by adding Fe to Ti-Ni-Cu ternary alloys.
남태현 국립경상대학교 공과대학 부설 첨단소재연구소 1992 尖端素材 Vol.2 No.-
The crystal structure of a Ti-Ni hydride formed by electrochemical hydrogenation in a Ti-48Ni-2Al (at%) alloy has been investigated by electron microscopy and diffraction, and was found to be a body centered tetragonal whose lattice parameters were a=0.62nm and c=1,24nm, hydrogen atoms being located at (000) and (1/2 1/2 1/2) of the unit cell. Orietation relationship between the parent(B2) and hydride lattice was 〔100〕?//〔100〕?, (001)?//(001)?. Irrespective of whether the electrochemical hydrogenation was made in the parent state or martensitic state, the obtained hydrides were identical in crystal structure and similar in morphology. 1/2-extra reflections previously often observed in the parent state of TiNi alloys (including 0 0 1/2, 1/2 1/2 0, 1/2 1/2 1/2 and 0 1/4 2/4 reflections) were found to be due to the formation of the hydride.
남태현 국립경상대학교 공과대학 부설 첨단소재연구소 1991 尖端素材 Vol.1 No.-
Shape memory characteristics of a thermo-mechanically treated Ti-40Ni- 10Cu (at%) alloy have been investigated by means of electrical resistivity measurement, differential scanning calorimetry, X-ray diffraction and thermal cycling test under constant load, and then were compared with those of a solution treated Ti-40Ni-10Cu alloy. The following results are obtained. (1)The transformation occurs in two stage, i. e., B2↔B19↔B19', in both the thermo-mechanically treated and solution treated conditions. (2)Both the B2↔B19 and B19↔B19' transformation start temperatures are increased by thermo-mechanical treatments. (3)The transformation hysteresis and maximum recoverable elongation associated with the B2↔B19 transformation is increased from 11K to 16K and from 3.2% to 3.7% respectively, by thermo-mechanical treatments.