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Jinru Luo,Yaqiong Yan,Jishan Zhang,Linzhong Zhuang 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.4
A strongly basal textured AZ31 magnesium alloy were cryorolled at liquid-nitrogen temperature at various strains. The microstructure and texture of the rolled sheets have been investigated using electron backscatter diffraction (EBSD) and X-ray diffraction. The microstructural and textural evolutions of the AZ31 magnesium alloy during cryorolling have been discussed. A lot of twins were observed in the rolled sheets. The influence of strain on the twin types and variant selection during cryorolling for the magnesium alloy has been discussed quantitatively based on the orientation data collected using EBSD. The influence of the twins on the microstructural and textural evolutions for the AZ31 magnesium alloy during cryorolling has also been discussed. The mechanical properties of the cryorolled sheets were tested by uniaxial tensile tests at the ambient temperature with a strain rate 10 -3 s -1 in the tensile direction respectively along the rolling and transverse directions of the rolled sheets. The relationships between the mechanical properties and microstructure of the cryorolled sheets have been discussed in the present work. The active twinning during rolling at that cryogenic temperature has been found to play an important role in influencing the microstructure, texture, as well as the mechanical properties of the AZ31 magnesium alloy.
Changhao Wang,Yu Luo,Jinru Luo,Xiao Song,Wei Zhang,Pinghuai Wang,Zhenghao Liu,Maoyin Wang,Xinghui He,Linjiang Chai 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.4
Titanium alloys are one of the most important structural materials for the aerospace applications, which bring active studyon microstructural and mechanical optimization of the alloys. In the present study, commercial TA2 titanium sheets withdifferent initial textures were rolled to a strain of 4% at liquid nitrogen temperature. Microstructures of the rolled sheets werecharacterized using a scanning electron microscope equipped with an EBSD detector and their mechanical properties weretested through quasi-static uniaxial tension tests at room temperature. The influence of the initial texture on the microstructureand mechanical performance of the cryorolled sheet were discussed. Twinning is found to occur in the TA2 sheets after rollingeven at a small strain. Initial texture is an important factor affecting both numbers and types of the twins. {11–22} contractiontwinning is always the dominating type of twins for all three sheets having different initial textures. A lot of {11–22}and {11–24} twins can be found in the sheets with the initial texture of C-axes//ND, while the sheet with an initial texture ofC-axes away from the ND contains few twins, with a high density of dislocations developed instead. Along with contractiontwinning, many {10–12} and {11–21} twins are detected in the sheet with the initial texture of C-axes⊥ND. The cryorolledsheet having the densest twins shows the best mechanical properties, indicating a beneficial effect of a small pre-strain.
Kaiyin Zhao,Lijun Zhao,Jinru Hou,Zhongxu Feng,Wenzhi Jiang 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.3
The technology of vibratory mixing has been applied to improve the compressive strength of cement-stabilized macadam (CSM). The aim of this study is to investigate the effect of vibration acceleration and cement dosage on the unconfined compressive strength and density of CSM. The mixtures with four cement dosages (2%, 3%, 4%, and 5%) were prepared by conventional mixing (0 g) and vibratory mixing (1 g, 2 g, and 3.5 g). The unconfined compressive strength was tested under different mixing methods. And the microstructure of CSM was analyzed by scanning electron microscope. The results indicate that samples using vibratory mixing have higher strengths, lower coefficient of variation, and denser microstructures, compared with the conventional compulsory mixing. Compared with 15% in conventional mixing, the strength variable coefficient of CSM is less than 10% in the vibratory mixing method. As the cement dosage and the vibration acceleration increase, the unconfined compressive strength increases. However, cement dosage has a more significant influence on improving the unconfined compressive strength than the mixing method. With the increase of every 1% in cement dosage, the 7-day strength of conventional mixing and in vibratory mixing average increased by 59% and 38%, respectively. However, the maximum improvement rate of the UCS value is 20–56.7% when vibration acceleration increased from 0 to 1 g. Especially when cement dosage is high, the effect of vibratory mixing on improving strength is limited. Besides, vibratory mixing reduces the original cement dosage by over 1.6% with the qualified unconfined compressive strength at vibration acceleration of 2 g, which is recommended in construction practice.
S. Hossein Hosseini Moghaddam,Xin Du,Jun Li,Jinru Cao,Boxiong Zhong,YuYin Chen 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.5
Proteomes of heat tolerant (multivoltine) and heat susceptible (bivoltine) silkworms (Bombyx mori) in response to heat shock were studied. Detected proteins from fat body were identified by using MALDI-TOF/TOF spectrometer, MS/MS, and MS analysis. Eight proteins, including small heat shock proteins (sHSPs) and HSP70, were expressed similarly in both breeds, while 4 protein spots were expressed specifically in the bivoltine breed and 12 protein spots were ex-pressed specifically in the multivoltine breed. In the present proteomics approach, 5 separate spots of sHSP proteins (HSP19.9, HSP20.1, HSP20.4, HSP20.8, and HSP21.4) were identified. Protein spot intensity of sHSPs was lower in the multivoltine breed than in the bivoltine breed after the 45C heat shock treatment, while the difference between two breeds was not significant after the 41C heat shock treatment. These results indicated that some other mechanisms might be engaged in thermal tolerance of multivotine breed except for the expression of sHSP and HSP70. There were visible differences in the intensity of heat shock protein expression between male and female, however, differences were not statistically significant.