The effects of pre-deformation following solution treatment on the microstructure and mechanical properties of aged high purity Al-Cu-Mg alloy were studied by tensile test, micro-hardness measurements, transmission el...The effects of pre-deformation following solution treatment on the microstructure and mechanical properties of aged high purity Al-Cu-Mg alloy were studied by tensile test, micro-hardness measurements, transmission electron microscopy and scanning electron microscopy. The micro-hardness measurements indicate that compared with un-deformed samples, the peak hardness is increased and the time to reach peak hardness is reduced with increasing pre-strain. Additionally, a double-peak hardness evolution behavior of cold-rolled （CR） samples was observed during aging. The results of TEM observation show that the number density of S′（Al2CuMg） phase is increased and the size is decreased in CR alloy with increase of pre-strain. The peak hardness and peak strength of the CR alloy are increased because of quantity increasing and refinement of S′ phase and high density dislocation.展开更多
An artificial neural network （ANN） model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on...An artificial neural network （ANN） model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on the dc and their de values were predicted by the ANN model. Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were prepared by injecting into copper mold. The amorphous structures and the determination of the dc of as-cast alloys were ascertained using X-ray diffraction. The results show that the predicted de values of glass forming alloys are in agreement with the corresponding experimental values. Thus the developed ANN model is reliable and adequate for designing the composition and predicting the de of glass forming alloy.展开更多
The effect of pre-deformation followed by or together with artificial aging on the mechanical properties as strength and ductility of an AA6060 aluminium alloy was studied. AA6060 was initially cast, homogenized and e...The effect of pre-deformation followed by or together with artificial aging on the mechanical properties as strength and ductility of an AA6060 aluminium alloy was studied. AA6060 was initially cast, homogenized and extruded according to standard industrial practice. The extruded material was then subjected to a solution heat treatment and subsequently artificial aging after （sequential mode） and during （simultaneous mode） various combinations of deformation （0-10%） and heat treatments. The aging behaviour and mechanical properties were characterized in terms of Vickers hardness and tensile testing. It is found that precipitation kinetics and associated mechanical response, in terms of hardness and tensile properties are strongly affected by pre-deformations. In terms of aging behaviour, kinetics is accelerated and the peak strength generally increases. Comparing sequential mode and simultaneous mode, the latter seems to give overall better mechanical properties and after considerably shorter aging times. The results of the two modes of pre-deformation are compared and discussed in view of differences in processing conditions and microstructure characteristics.展开更多
Many researchers in China are actively engaged in the development of new types of wrought magnesium alloys with low cost or with high-performances and novel plastic processing technologies.The research activities are ...Many researchers in China are actively engaged in the development of new types of wrought magnesium alloys with low cost or with high-performances and novel plastic processing technologies.The research activities are funded primarily through four government-supported programs:the Key Technologies R&D Program of China,the National Basic Research Program of China,the National High-tech R&D Program of China,and the National Natural Science Foundation of China.The key R&D activities for the development of new wrought magnesium alloys in China are reviewed,and typical properties of some new alloys are summarized. More attentions are paid to high-strength wrought magnesium alloys and high-plasticity wrought magnesium alloys.Some novel plastic processing technologies,emerging in recent years,which aim to control deformation texture and to improve plasticity and formability especially at room temperature,are also introduced.展开更多
A new prosthetic hand with a fixed thumb and four fingers actuated by Shape Memory Alloy （SMA） type artificial muscle has been developed in this paper. Different from typical geared motor, SMA actuator is lightweigh...A new prosthetic hand with a fixed thumb and four fingers actuated by Shape Memory Alloy （SMA） type artificial muscle has been developed in this paper. Different from typical geared motor, SMA actuator is lightweight and silent, however shows a little short stroke and small attracting force per each unit. In order to achieve enough output force and motion range of each finger, multiple SMA type artificial muscles with special device which facilitates enough length are equipped in the hand. The fundamental properties of the SMA type artificial muscle including output force and electrical response were determined experimentally and considered for the design of hand mechanism. Besides, the structure of each finger and whole system has been designed based on observation of human hand. The electrical hardware to control multiple shape memory alloy type artificial muscles has been also developed. Finally, the usefulness of the prosthetic hand has been investigated through experiments for grasping several types of objects.展开更多
Additive manufacturing technology has been developed in Xi＇ an Jiaotong University for almost 20 years. Up to now~ it is still attracting the attentions of the researchers or manufacturers all over the world. Some in...Additive manufacturing technology has been developed in Xi＇ an Jiaotong University for almost 20 years. Up to now~ it is still attracting the attentions of the researchers or manufacturers all over the world. Some in- novative processes and frontier application research are all being conducted here to catch up with the new develop- ment of this technology. In the paper, newly developed processes, such as ultraviolet-light emitting diode （UV- LED） stereolithography, ceramic stereolithography, and direct metal forming, were described. Some results of the frontier application researches, such as indirect fabrication of ceramic casting mould, wind-tunnel-testing models, photonic crystals and metamatcrials, were also briefly reviewed.展开更多
In his government work report,Premier Li Keqiang vowed to deepen the reform of the financial sector in 2016.It includes efforts to improve the financial regulatory system,further liberalize interest rates and improve ...In his government work report,Premier Li Keqiang vowed to deepen the reform of the financial sector in 2016.It includes efforts to improve the financial regulatory system,further liberalize interest rates and improve the market-based mechanism for setting the yuan exchange rate.展开更多
基金Project(51301209)supported by the National Natural Science Foundation of China
文摘The effects of pre-deformation following solution treatment on the microstructure and mechanical properties of aged high purity Al-Cu-Mg alloy were studied by tensile test, micro-hardness measurements, transmission electron microscopy and scanning electron microscopy. The micro-hardness measurements indicate that compared with un-deformed samples, the peak hardness is increased and the time to reach peak hardness is reduced with increasing pre-strain. Additionally, a double-peak hardness evolution behavior of cold-rolled （CR） samples was observed during aging. The results of TEM observation show that the number density of S′（Al2CuMg） phase is increased and the size is decreased in CR alloy with increase of pre-strain. The peak hardness and peak strength of the CR alloy are increased because of quantity increasing and refinement of S′ phase and high density dislocation.
基金Project(50874045)supported by the National Natural Science Foundation of China
文摘An artificial neural network （ANN） model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on the dc and their de values were predicted by the ANN model. Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were prepared by injecting into copper mold. The amorphous structures and the determination of the dc of as-cast alloys were ascertained using X-ray diffraction. The results show that the predicted de values of glass forming alloys are in agreement with the corresponding experimental values. Thus the developed ANN model is reliable and adequate for designing the composition and predicting the de of glass forming alloy.
基金Project (176816/I40) supported by the Research Council of Norway
文摘The effect of pre-deformation followed by or together with artificial aging on the mechanical properties as strength and ductility of an AA6060 aluminium alloy was studied. AA6060 was initially cast, homogenized and extruded according to standard industrial practice. The extruded material was then subjected to a solution heat treatment and subsequently artificial aging after （sequential mode） and during （simultaneous mode） various combinations of deformation （0-10%） and heat treatments. The aging behaviour and mechanical properties were characterized in terms of Vickers hardness and tensile testing. It is found that precipitation kinetics and associated mechanical response, in terms of hardness and tensile properties are strongly affected by pre-deformations. In terms of aging behaviour, kinetics is accelerated and the peak strength generally increases. Comparing sequential mode and simultaneous mode, the latter seems to give overall better mechanical properties and after considerably shorter aging times. The results of the two modes of pre-deformation are compared and discussed in view of differences in processing conditions and microstructure characteristics.
基金Project(50725413)supported by the National Natural Science Foundation of ChinaProject(2007CB613704)supported by the National Basic Research Program of ChinaProject(2008DFR50040)supported by the International Cooperation Program of Ministry of Science and Technology of China
文摘Many researchers in China are actively engaged in the development of new types of wrought magnesium alloys with low cost or with high-performances and novel plastic processing technologies.The research activities are funded primarily through four government-supported programs:the Key Technologies R&D Program of China,the National Basic Research Program of China,the National High-tech R&D Program of China,and the National Natural Science Foundation of China.The key R&D activities for the development of new wrought magnesium alloys in China are reviewed,and typical properties of some new alloys are summarized. More attentions are paid to high-strength wrought magnesium alloys and high-plasticity wrought magnesium alloys.Some novel plastic processing technologies,emerging in recent years,which aim to control deformation texture and to improve plasticity and formability especially at room temperature,are also introduced.
文摘A new prosthetic hand with a fixed thumb and four fingers actuated by Shape Memory Alloy （SMA） type artificial muscle has been developed in this paper. Different from typical geared motor, SMA actuator is lightweight and silent, however shows a little short stroke and small attracting force per each unit. In order to achieve enough output force and motion range of each finger, multiple SMA type artificial muscles with special device which facilitates enough length are equipped in the hand. The fundamental properties of the SMA type artificial muscle including output force and electrical response were determined experimentally and considered for the design of hand mechanism. Besides, the structure of each finger and whole system has been designed based on observation of human hand. The electrical hardware to control multiple shape memory alloy type artificial muscles has been also developed. Finally, the usefulness of the prosthetic hand has been investigated through experiments for grasping several types of objects.
文摘Additive manufacturing technology has been developed in Xi＇ an Jiaotong University for almost 20 years. Up to now~ it is still attracting the attentions of the researchers or manufacturers all over the world. Some in- novative processes and frontier application research are all being conducted here to catch up with the new develop- ment of this technology. In the paper, newly developed processes, such as ultraviolet-light emitting diode （UV- LED） stereolithography, ceramic stereolithography, and direct metal forming, were described. Some results of the frontier application researches, such as indirect fabrication of ceramic casting mould, wind-tunnel-testing models, photonic crystals and metamatcrials, were also briefly reviewed.
文摘In his government work report,Premier Li Keqiang vowed to deepen the reform of the financial sector in 2016.It includes efforts to improve the financial regulatory system,further liberalize interest rates and improve the market-based mechanism for setting the yuan exchange rate.
