http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Al-5.2Si-3.4Cu-0.28Mg 합금의 미세조직 및 기계적 특성에 미치는 용체화 및 시효 열처리의 영향
조의제,정제기,박용호 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.12
Since strength and ductility have a trade-off relationship in Al alloys, controlling these properties using heat treatments requires careful attention to the dissolution and evolution of the reinforcing phases. In this study, the effects of solution and aging treatments on the microstructure and mechanical properties of Al-5.2Si-3.4Cu-0.28Mg alloy were investigated. 1-step and 2-step solution treatments were conducted at 495 and 520 ℃ with various holding times, which were determined by thermal analysis. At 495 ℃, the eutectic θ(Al2Cu) phases were quickly dissolved while block-shaped θ phases remained, even until 13 hours. During the 2-step treatment at 520 ℃, these remaining phases were melted both in the grains and boundaries. Although all of the Q(Al5Cu2Mg8Si6) phases were completely dissolved in the 2-step treatment, the hardness of the 2-step treated specimen was lower than the 1-step treated one. After solution treatments at 495 ℃/9 hours, where the highest hardness was observed, artificial aging treatments were conducted at 160 and 200 ℃ with various times. Yield and ultimate tensile strengths showed similar values at the peak aging regardless of the temperature, while higher hardness (117%) and elongation (281%) were obtained at 160 than 200 ℃. Based on the observed results, the correlations between the microstructures and mechanical properties by the heat treatments were investigated.
조의제,김동완,임재영 대한금속·재료학회 2020 대한금속·재료학회지 Vol.58 No.9
Because of their simplicity and low equipment costs, various oxidation methods can be used to create metal oxides, but they still require long processing times and/or high temperatures. In this study, a new electrochemical oxidation (ECO) method, which oxidizes metal in DI water with a constant flowing current to both the cathode and anode, was developed to overcome the disadvantages of conventional oxidation methods. The mechanism of the ECO method is discussed. Metallic Zn films were oxidized by the ECO method in DI water for 1 h. The DI water temperature was varied from 30 to 90 oC to determine the optimal temperature for the ECO process. Increasing the temperature of the DI water led to distinct surface changes in the disk-shaped Zn plate. The intensity of diffraction peaks from the ZnO (002) plane gradually increased from 31.67 to 2806.48. The structural and optical properties of the ZnO thin film were enhanced as the temperature of the DI water approached 90 oC, which means that a high-quality ZnO thin film was synthesized using the ECO method at lower temperatures and shorter processing time compared with established oxidation methods. These results confirm the ECO method can be useful for the low-cost fabrication of transparent and flexible optoelectronic devices.