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Lamellar TiAl 합금의 고온 저주파 피로 파괴거동에 미치는 압축 유지시간의 효과
朴永森,양성진,南壽祐,朴永宇,黃善根,金洛俊 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.4
Total strain range controlled low cycle fatigue tests have been conducted in lamellar Ti-46.6Al;-1.4Mn-2Mo (at.%) alloy at 800℃ in order to investigate the effect of compressive hold time on high-temperature low cycle fatigue fracture behavior. It is observed that fatigue life decreases with imposing compressive hold time. The experimental results clearly indicate that the imposed compressive hold time accelerates α_2→γ phase transformation at the grain boundary to induce the formation of grain boundary γ phase. Because grain boundary γ phase is proved to be the region where plastic deformation is easily concentrated, it is confirmed that imposed compressive hold time decreases low cycle fatigue life by inducing grain boundary weakness and intergranular cracking.
Ni 함량과 W 결정립 크기에 따른 W-Ni 활성소결체의 고온압축 특성
박영삼,오승탁,양주환,김영도,문인형 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.2
High temperature deformation behavior of activated sintered W powder compacts was investigated. The compression tests were carried out in the temperature range between 900 and 110$0^{\circ}C$ at the strain rate of $10^{-3}s^{-1}$. The sintered specimens of Ni-doped submicron W powder compacts showed decrease in W grain size with increasing the Ni content. As the result, the flow stress was significantly increased with increasing the Ni content. We obtained Ni-activated sintered W compacts with the relative density of 94 $\pm$ l%and the average grain size of less than 5${\mu}{\textrm}{m}$. A moderate true strain up to 0.60 was obtained without fracture even at 110$0^{\circ}C$ with the strain rate of $10^{-3}s^{-1}$ for the activated W compact despite adding the 1.0 wt%Ni to submicron W powder.