In this work,we synthesized a brand-new Al foam with a periodic structure via a simple powder metallurgical route.The periodic architecture consists of both hierarchical porous and bi-directional composition-graded st...In this work,we synthesized a brand-new Al foam with a periodic structure via a simple powder metallurgical route.The periodic architecture consists of both hierarchical porous and bi-directional composition-graded structures.The results show that the hierarchical porous material includes large pores on millimeter scale inheriting from the hollow structure of the Al tubes,and small pores on mi-crometer scale produced by the sintering of Al/Mg powders.The bi-directional Mg concentration-graded structure is formed in the tube walls due to the condensation of Mg vapor in the inner tube wall.The addition of Mg powders achieves excellent metallurgical bonding between the Al powders and the hollow tubes at 550℃.The plateau stress and energy absorption capacity of the Al foam in y-axis compression are significantly higher than that in the x-axis due to their anisotropic structure.In general,the Al foam with Mg addition presents the most superior compression performance,and we believe that our find-ings could open up a unique strategy for developing high-performance metallic foams with the periodic architecture involving both hierarchical porous and bi-directional graded structure.展开更多
A Fe/Al clad tube was prepared by explosive welding.Then the bonding characteristic of the interface was investigated by compression,flattening and compression-shear test.The test results exhibit that the clad tubes p...A Fe/Al clad tube was prepared by explosive welding.Then the bonding characteristic of the interface was investigated by compression,flattening and compression-shear test.The test results exhibit that the clad tubes possessing good bonding interface have higher shear strength than that of pure aluminum and can bear both axial and radial deformation.The original interface between aluminum layer and ferrite layer was observed by scanning electron microscopy（SEM）.The results show that the clad tubes with good bonding properties possess the interface in wave and straight shape.The Fe/Al clad tube was used to manufacture the T-shape by hydro-bulging.It is found that the good-bonding interface of the Fe/Al clad tube plays a dominant role in the formation of the T-shape.展开更多
An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. Here,...An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. Here, the controller is introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. When the controller were used, the experimental results of crushing of square tubes controlled by the controller＇s elements showed a good candidate for a controllable energy absorption capability in impact crushing.展开更多
The drop tube technique was performed to achieve rapid solidification of undercooled Al 18%Si hypereutectic alloy. The droplets ranging from 60～1 000 μm in diameter were obtained. The regular polygonal primary Si an...The drop tube technique was performed to achieve rapid solidification of undercooled Al 18%Si hypereutectic alloy. The droplets ranging from 60～1 000 μm in diameter were obtained. The regular polygonal primary Si and lamellar eutectic homogeneously distribute on α (Al) matrix in the droplets larger than 500 μm. While in the droplets smaller than 500 μm the five star primary Si was found, which is often accompanied by some spherical eutectic grains. The different morphologies of primary Si are due to varied undercoolings. Scanning electron microscopy suggests that the spherical eutectic grain is composed of anomalous eutectic in its core and lamellar eutectic radiating outside from its periphery. Such eutectic microstructure is presumed to be the result of combining large undercooling, microgravity with containerless processing during free fall. [展开更多
基金financially supported by the National Key R&D Program of China(No.2021YFB3802300)the Guang-dong Major Project of Basic and Applied Basic Research(No.2021B0301030001)+1 种基金supported by the National Natural Science Foundation of China(Nos.51804239,51972252,and 52171045)the Fundamen-tal Research Project at Zhongshan City in Guangdong province(No.2020B2013).
文摘In this work,we synthesized a brand-new Al foam with a periodic structure via a simple powder metallurgical route.The periodic architecture consists of both hierarchical porous and bi-directional composition-graded structures.The results show that the hierarchical porous material includes large pores on millimeter scale inheriting from the hollow structure of the Al tubes,and small pores on mi-crometer scale produced by the sintering of Al/Mg powders.The bi-directional Mg concentration-graded structure is formed in the tube walls due to the condensation of Mg vapor in the inner tube wall.The addition of Mg powders achieves excellent metallurgical bonding between the Al powders and the hollow tubes at 550℃.The plateau stress and energy absorption capacity of the Al foam in y-axis compression are significantly higher than that in the x-axis due to their anisotropic structure.In general,the Al foam with Mg addition presents the most superior compression performance,and we believe that our find-ings could open up a unique strategy for developing high-performance metallic foams with the periodic architecture involving both hierarchical porous and bi-directional graded structure.
基金Project(BA2006067)supported by Achievement Transitional Foundation of Jiangsu Province,China
文摘A Fe/Al clad tube was prepared by explosive welding.Then the bonding characteristic of the interface was investigated by compression,flattening and compression-shear test.The test results exhibit that the clad tubes possessing good bonding interface have higher shear strength than that of pure aluminum and can bear both axial and radial deformation.The original interface between aluminum layer and ferrite layer was observed by scanning electron microscopy（SEM）.The results show that the clad tubes with good bonding properties possess the interface in wave and straight shape.The Fe/Al clad tube was used to manufacture the T-shape by hydro-bulging.It is found that the good-bonding interface of the Fe/Al clad tube plays a dominant role in the formation of the T-shape.
文摘An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. Here, the controller is introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. When the controller were used, the experimental results of crushing of square tubes controlled by the controller＇s elements showed a good candidate for a controllable energy absorption capability in impact crushing.
文摘The drop tube technique was performed to achieve rapid solidification of undercooled Al 18%Si hypereutectic alloy. The droplets ranging from 60～1 000 μm in diameter were obtained. The regular polygonal primary Si and lamellar eutectic homogeneously distribute on α (Al) matrix in the droplets larger than 500 μm. While in the droplets smaller than 500 μm the five star primary Si was found, which is often accompanied by some spherical eutectic grains. The different morphologies of primary Si are due to varied undercoolings. Scanning electron microscopy suggests that the spherical eutectic grain is composed of anomalous eutectic in its core and lamellar eutectic radiating outside from its periphery. Such eutectic microstructure is presumed to be the result of combining large undercooling, microgravity with containerless processing during free fall. [
