In order to investigate the existing form and action mechanism of minor scandium (Sc) and zirconium (Zr) in Al-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-...In order to investigate the existing form and action mechanism of minor scandium (Sc) and zirconium (Zr) in Al-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-cast, homogenized, hot-rolled, as-solution and natural aged, were observed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It is revealed that Sc and Zr are completely dissolved into the supersaturated solid solution in as-cast ingot, but grain refinement is not observed. Coffee-bean-like Al3(Sc, Zr) particles deposit during homogenization of ingot induce an increase in hardness. Al3(Sc, Zr) particles are slightly coarsened in as-solution samples, but they still maintain coherent to matrix, which indicates a high thermal stability of these particles. Good coherency of Al3(Sc, Zr) particles makes some benefits for inhibiting recrystallization and reserving work-hardening.展开更多
When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing w...When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing wave or a short-crested wave in front of the wall. This paper presents the experimental observations of sand bed configurations under the action of these water waves in front of the wall. The geometry of sand ripples under these water waves in front of the vertical wall is presented as a function of flow parameters, such as the water particle semi-excursion and the mobility number.展开更多
基金Project(2005DFA50550) supported by International Science and Technology Cooperation Program of ChinaProject(2005CB623705) supported by the National Basic Research Program of China
文摘In order to investigate the existing form and action mechanism of minor scandium (Sc) and zirconium (Zr) in Al-Cu-Mg alloy, microstructures of Al-4Cu-1Mg-Sc-Zr alloy under different conditions, including states of as-cast, homogenized, hot-rolled, as-solution and natural aged, were observed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It is revealed that Sc and Zr are completely dissolved into the supersaturated solid solution in as-cast ingot, but grain refinement is not observed. Coffee-bean-like Al3(Sc, Zr) particles deposit during homogenization of ingot induce an increase in hardness. Al3(Sc, Zr) particles are slightly coarsened in as-solution samples, but they still maintain coherent to matrix, which indicates a high thermal stability of these particles. Good coherency of Al3(Sc, Zr) particles makes some benefits for inhibiting recrystallization and reserving work-hardening.
文摘When a 2-D progressive wave train normally or obliquely approaches a vertical wall and then is normally or obliquely reflected from it, the combination of the approaching and reflected waves may result in a standing wave or a short-crested wave in front of the wall. This paper presents the experimental observations of sand bed configurations under the action of these water waves in front of the wall. The geometry of sand ripples under these water waves in front of the vertical wall is presented as a function of flow parameters, such as the water particle semi-excursion and the mobility number.
