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Hf 가 첨가된 Fe-30at.%A1-5at.%Cr 합금의 미세조직 및 열간압연가공 특성
윤계림(Kye Lim Yoon),이도재(Doh Jae Lee),백대화(Dae Hwa Baek),이경구(Kyung Ku Lee) 한국주조공학회 2001 한국주조공학회지 Vol.21 No.6
N/A This study was carried out to examine the effects of adding 0.3at.%Hf in Fe-30at.%Al-5at.%Cr alloy on the variation of microstructures and hot workability. The effect of hot rolling on mechanical properties was estimated by measuring the elongation and tensile strength after rolling at 800 and 1000 respectively. Microstructure of Fe-30at.%Al-5at.%Cr alloy was consisted of large equiaxed grains and it was changed to quasi-equiaxed or columnar structures by adding 0.3at.%Hf to Fe-30at.%Al-5at.%Cr alloy. Every specimens showed a decreased tensile strength after hot rolling compared to that of before rolling. The elongation was increased by hot rolling. Remarkable changes in elongation by hot rollong was observed such as from 1.4% to 4.5% elongation at the specimen of 0.3at.%Hf added to Fe-30at.%Al-5at.%Cr. Fe-30at.%Al-5at.%Cr alloy showed typical cleavage fracture on tensile failure and hot rolling has negligible effects on fracture mode in this alloy. However at the alloy containing Hf fracturemode was changed by hot rolling from intergranular to mixed intergranular and transgranular fracture mode.
생체용 Ti합금의 산화거동에 미치는 Ta 및 Nb 첨가의 영향
이도재,오태욱,박범수,김수학,전충극,윤계림,Lee Doh-Jae,Oh Tae-Wook,Park Bum-Su,Kim Soo-Hak,Jun Choong-Geug,Yoon Kye-Lim 한국재료학회 2004 한국재료학회지 Vol.14 No.3
The oxidation behaviors of Ti-10Ta-10Nb alloy and Ti-6Al-4V alloy were studied in dry air atmosphere. Specimens were melted in consumable vacuum arc furnace and homogenized at $1050^{\circ}C$ for 24 h. Hot rolling was performed at $1000^{\circ}C$. Specimens of the alloys were oxidized as the temperature range $400~650^{\circ}C$ for 30 min. The oxidation behavior of the alloys was analysed by optical microscope, SEM/EDX, XRD, XPS and TGA. Immersion test was performed in 1% Lactic acid. In the microscope observation, oxide layer of Ti-10Ta-10Nb alloy was denser and thinner than Ti-6Al-4V's. The weight gains during the oxidation rapidly increased at the temperature above $600^{\circ}C$ in Ti-6Al-4V's alloy and$ 700^{\circ}C$ in Ti-10Ta-10Nb alloy. According to XRD results, oxide layers were composed of mostly $TiO_2$(rutile) phase. It was analysed that the passive film of the Ti alloys consisted of $TiO_2$ through X-ray photoelectron spectroscopy(XPS) analysis.
가공 열처리에 따른 Ti-10Ta-10Nb합금의 미세조직 및 기계적 특성 변화
이도재 ( Doh Jae Lee ),황주영 ( Ju Young Hwang ),이경구 ( Kyung Ku Lee ),윤계림 ( Kye Lim Yoon ),전충극 ( Choong Geug Jun ) 한국열처리공학회 2005 熱處理工學會誌 Vol.18 No.2
N/A Both commercially pure titanium and Ti-6AI-4V alloy have been widely used as biomaterials because of their excellent biocompatibility, corrosion resistance and mechanical properties. However, in recent years, vanadium has been found to cause cytotoxic effects and adverse tissue reactions, while aluminium has been associated with potential neurological disorders. A newly designed α+ß type Ti alloy, Ti-10Ta-10Nb alloy showed superior properties to CP Ti and Ti-6AI-4V alloy in the point of biomaterial, and elucidated the future uses as a biomaterial. Microstructural changes of Ti-10Ta-10Nb alloy after hot-rolling, warm-rolling, solution and aging treatment were investigated. According to TEM results, the microstructures after solution treatment were composed of mostly α phase with a trace of ß phase due to adding ß-phase stabilizer tantalum and niobium. The microstructures after warm-rolling is coarse and elongated a phase and hot rolling resulted in very fine a widmansta¨tten. The highest value of hardness was obtained by aging treatment at 400℃ for 20hr in which microstructure consisted of very fine a phase in β matrix.