Depression refers to a series of mental health issues characterized by loss of interest and enjoyment in everyday life,low mood and selected emotional,cognitive,physical and behavioral symptoms.Depression is a common ...Depression refers to a series of mental health issues characterized by loss of interest and enjoyment in everyday life,low mood and selected emotional,cognitive,physical and behavioral symptoms.Depression is a common disorder,affecting 5–15%of the general population.When diagnosed as major depressive disorder（MDD）,patients are currentlytreated with pharmacological agents such as serotonin or noradren- aline uptake inhibitors （SSRI or SNRI） or tricyclics.展开更多
A novel variant of friction stir welding process, referred as ultrasonic vibration enhanced friction stir welding, is developed to transmit ultrasonic vibration energy directly into the localized area of the workpiece...A novel variant of friction stir welding process, referred as ultrasonic vibration enhanced friction stir welding, is developed to transmit ultrasonic vibration energy directly into the localized area of the workpiece near and ahead of the rotating tool. Experiments are conducted on 6061-T4 aluminium alloy plates by this new process and the conventional friction stir welding process, respectively. The morphology and macrograph of the welds under both conditions are observed and contrasted. The experimental results show that ultrasonic vibration enhanced friction stir welding can improve the weld formation quality and increase the welding efficiency. And it just needs a smaller axial downward force. Because that the added action of ultrasonic vibration energy may enhance the localized softening extent and the plastic flow around the tool. In addition, it also improves the mechanical properties of the welded joints.展开更多
An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characteriz...An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characterized via electron back-scattered diffraction,transmission Kikuchi diffraction and scanning transmission electron microscopy.From the tail of the gage to the necking region,the microstructure of the material evolved from low-angle grain boundaries(LAGB s) to mixtures of LAGBs and high-angle grain boundaries(HAGBs),and fine equiaxed recrystallized grains.The elongation to failure in the tensile test exceeds 167%.During the hot deformation,continuous dynamic recrystallization of the austenitic matrix was promoted by the multiple secondary phases.The dislocations introduced by the secondary phases were rearranged and continuously transformed into HAGBs.The initially coarse grains(30.5 μm) were refined into ultra-fine equiaxed grains(1 μm),which contributed significantly the enhanced plasticity during hot deformation of the steel.In the necking area of the sample,twins were nucleated in the stress concentration regions and accommodated the local strain by discontinuous dynamic recrystallization,which was also beneficial to improving the plasticity.展开更多
基金funded by Ministry of Education,University and Research(MIUR)ex-60% research fund University of Brescia,Italy
文摘Depression refers to a series of mental health issues characterized by loss of interest and enjoyment in everyday life,low mood and selected emotional,cognitive,physical and behavioral symptoms.Depression is a common disorder,affecting 5–15%of the general population.When diagnosed as major depressive disorder（MDD）,patients are currentlytreated with pharmacological agents such as serotonin or noradren- aline uptake inhibitors （SSRI or SNRI） or tricyclics.
文摘A novel variant of friction stir welding process, referred as ultrasonic vibration enhanced friction stir welding, is developed to transmit ultrasonic vibration energy directly into the localized area of the workpiece near and ahead of the rotating tool. Experiments are conducted on 6061-T4 aluminium alloy plates by this new process and the conventional friction stir welding process, respectively. The morphology and macrograph of the welds under both conditions are observed and contrasted. The experimental results show that ultrasonic vibration enhanced friction stir welding can improve the weld formation quality and increase the welding efficiency. And it just needs a smaller axial downward force. Because that the added action of ultrasonic vibration energy may enhance the localized softening extent and the plastic flow around the tool. In addition, it also improves the mechanical properties of the welded joints.
文摘An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characterized via electron back-scattered diffraction,transmission Kikuchi diffraction and scanning transmission electron microscopy.From the tail of the gage to the necking region,the microstructure of the material evolved from low-angle grain boundaries(LAGB s) to mixtures of LAGBs and high-angle grain boundaries(HAGBs),and fine equiaxed recrystallized grains.The elongation to failure in the tensile test exceeds 167%.During the hot deformation,continuous dynamic recrystallization of the austenitic matrix was promoted by the multiple secondary phases.The dislocations introduced by the secondary phases were rearranged and continuously transformed into HAGBs.The initially coarse grains(30.5 μm) were refined into ultra-fine equiaxed grains(1 μm),which contributed significantly the enhanced plasticity during hot deformation of the steel.In the necking area of the sample,twins were nucleated in the stress concentration regions and accommodated the local strain by discontinuous dynamic recrystallization,which was also beneficial to improving the plasticity.
