The effectsof melt overheating degree on the undercooling degree and resultant solidification structures of Nd9Fe85-xTi4C2Bx（x=10, 12） glass-forming alloyswerestudied by differential thermal analysis combining with ...The effectsof melt overheating degree on the undercooling degree and resultant solidification structures of Nd9Fe85-xTi4C2Bx（x=10, 12） glass-forming alloyswerestudied by differential thermal analysis combining with solidification structure analysis. The results indicate that the undercooling degree of Nd9Fe85-xTi4C2Bx（x=10, 12） alloys significantly increaseswith the rise of melt overheating degree, and two overheating degree thresholds corresponding to the drastic increase of the mean undercooling degree are found for each of the alloys. The existence of two turning points of the mean undercooling degreescan be linked to the structure transitions inside the overheated melts, which result in the evident increase of volume fraction of amorphous phasein the solidified structures.展开更多
The plastic deformation processes of magnesium alloys near a void at atomic scale level were examined through molecular dynamics(MD)simulation.The modified embedded atom method(MEAM)potentials were employed to charact...The plastic deformation processes of magnesium alloys near a void at atomic scale level were examined through molecular dynamics(MD)simulation.The modified embedded atom method(MEAM)potentials were employed to characterize the interaction between atoms of the magnesium alloy specimen with only a void.The void growth and crystal failure processes for hexagonal close-packed(hcp)structure were observed.The calculating results reveal that the deformation mechanism near a void in magnesium alloy is a complex process.The passivation around the void,dislocation emission,and coalescence of the void and micro-cavities lead to rapid void growth.展开更多
Controlling the thermal deformation is a crucial index for the design of the satellite antenna. To calculate and measure the satellite antenna’s thermal deformation is also an important step for the design of satelli...Controlling the thermal deformation is a crucial index for the design of the satellite antenna. To calculate and measure the satellite antenna’s thermal deformation is also an important step for the design of satellite antenna. Based on the foundation of equivalent assumption, the thermal deformation of the parabolic satellite antenna was analyzed by the finite element method for different design project. The best design project that had the minimum of the thermal deformation could be obtained through changing the lay-angle, lay-layers and lay-thickness of each layer. Results show the asymmetry structure has the minimum of thermal deformation. This paper may provide useful information for the further investigation on the coupling of thermal-stress structure.展开更多
Based on the microscopic elasticity theory and microscopic diffusion equation, the precipitation progress of the binary alloys including coherent strain energy was studied. The results show that coherent strain has ob...Based on the microscopic elasticity theory and microscopic diffusion equation, the precipitation progress of the binary alloys including coherent strain energy was studied. The results show that coherent strain has obvious effect on the coherent two-phase morphology and precipitation mechanism. With the increase of coherent strain energy, the particles shape changes from the randomly distributed equiaxed particels to elliptical precipitate shapes,their arrangement orientation increases; in the late stage of precipitation, the particle arrangement presents obvious directionality along the [10]and[01]directions, and the precipitation mechanism of alloy changes from typical spinodal decomposition mechanism to the mixture process which possesses the characteristics of both non-classical nucleation growth and spinodal decomposition mechanisms.展开更多
The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufac...The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively.展开更多
Deformation of ductile cuttings from sandstone in the mechanical compaction process was designed through the "experimental system of triaxial rock deformation",and the influence on porosity was studied by lo...Deformation of ductile cuttings from sandstone in the mechanical compaction process was designed through the "experimental system of triaxial rock deformation",and the influence on porosity was studied by looking into the deformation characteristics of ductile cuttings. The design indexes are as follows: simulated depth 0- 4 000 m,interval depth 500 m,and pressure range 0- 120 MPa at interval of 1. 5 MPa. The experimental results show that the porosity decreases as buried depth increases,indicating a negative relationship between them. The amount of compression was mainly obtained by porosity reduction and cutting deformation. Deformation of ductile cuttings is mainly ductile deformation; and deformation of crystal fragments is mainly expressed as brittle fracture,resulting in decrease of particle size. The research is of certain value for the exploration and development of oil and gas.展开更多
Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this p...Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this paper, a novel real-time measuring technology is developed for non-contact measuring the deformation behavior of heavy steel castings in heat treatment process. It was employed to measure the distortion and the temperature field of a batch of heavy turbine blade castings at cooling stage in normalizing process. Three inflection points appear in the distortion-time curves, and the residual distortion is affected by the regional area of not finished martensite transformation when the second inflection point appears. When the mean air temperature falls into the range of 10℃-20℃, the residual distortion is small; when it is lower than 10℃, positive distortion appears; when it is higher than 20℃, negative distortion appears. The distortion varies with seasonal temperature, which is directly responsible for the great machining allowance given in production.展开更多
基金Projects(51174121,51274125)supported by the National Natural Science Foundation of ChinaProject(2010R50016-30)supported by Zhejiang Province Science and Technology Innovation Team of Key Projects,ChinaProject supported by the K.C.Wong Magna Fund of Ningbo University,China
文摘The effectsof melt overheating degree on the undercooling degree and resultant solidification structures of Nd9Fe85-xTi4C2Bx（x=10, 12） glass-forming alloyswerestudied by differential thermal analysis combining with solidification structure analysis. The results indicate that the undercooling degree of Nd9Fe85-xTi4C2Bx（x=10, 12） alloys significantly increaseswith the rise of melt overheating degree, and two overheating degree thresholds corresponding to the drastic increase of the mean undercooling degree are found for each of the alloys. The existence of two turning points of the mean undercooling degreescan be linked to the structure transitions inside the overheated melts, which result in the evident increase of volume fraction of amorphous phasein the solidified structures.
基金Project(10776023)supported by the National Natural Science Foundation of China
文摘The plastic deformation processes of magnesium alloys near a void at atomic scale level were examined through molecular dynamics(MD)simulation.The modified embedded atom method(MEAM)potentials were employed to characterize the interaction between atoms of the magnesium alloy specimen with only a void.The void growth and crystal failure processes for hexagonal close-packed(hcp)structure were observed.The calculating results reveal that the deformation mechanism near a void in magnesium alloy is a complex process.The passivation around the void,dislocation emission,and coalescence of the void and micro-cavities lead to rapid void growth.
文摘Controlling the thermal deformation is a crucial index for the design of the satellite antenna. To calculate and measure the satellite antenna’s thermal deformation is also an important step for the design of satellite antenna. Based on the foundation of equivalent assumption, the thermal deformation of the parabolic satellite antenna was analyzed by the finite element method for different design project. The best design project that had the minimum of the thermal deformation could be obtained through changing the lay-angle, lay-layers and lay-thickness of each layer. Results show the asymmetry structure has the minimum of thermal deformation. This paper may provide useful information for the further investigation on the coupling of thermal-stress structure.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50071046)the National Hi-Tech Research and Development Program ofChina (Grant No.2002AA331051).
文摘Based on the microscopic elasticity theory and microscopic diffusion equation, the precipitation progress of the binary alloys including coherent strain energy was studied. The results show that coherent strain has obvious effect on the coherent two-phase morphology and precipitation mechanism. With the increase of coherent strain energy, the particles shape changes from the randomly distributed equiaxed particels to elliptical precipitate shapes,their arrangement orientation increases; in the late stage of precipitation, the particle arrangement presents obvious directionality along the [10]and[01]directions, and the precipitation mechanism of alloy changes from typical spinodal decomposition mechanism to the mixture process which possesses the characteristics of both non-classical nucleation growth and spinodal decomposition mechanisms.
基金Project(20122BAB206014)supported by National Natural Science Foundation of ChinaProject(51365038)supported by the Natural Science Foundation of Jiangxi Province,ChinaProject(GJJ13068)supported by the Science and Technology Program of Educational Committee of Jiangxi Province,China
文摘The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively.
基金Supported by joint project of CNOOC with Jilin University(No.CCL2012TJXSBS0282)
文摘Deformation of ductile cuttings from sandstone in the mechanical compaction process was designed through the "experimental system of triaxial rock deformation",and the influence on porosity was studied by looking into the deformation characteristics of ductile cuttings. The design indexes are as follows: simulated depth 0- 4 000 m,interval depth 500 m,and pressure range 0- 120 MPa at interval of 1. 5 MPa. The experimental results show that the porosity decreases as buried depth increases,indicating a negative relationship between them. The amount of compression was mainly obtained by porosity reduction and cutting deformation. Deformation of ductile cuttings is mainly ductile deformation; and deformation of crystal fragments is mainly expressed as brittle fracture,resulting in decrease of particle size. The research is of certain value for the exploration and development of oil and gas.
基金supported by the National Eleventh Five-Year Science and Technology Support Program of China (Grant No.2007BAF02B02)the Major Projects of Ministry of Science of China (Grant No.2009ZX04014-082)
文摘Distortion often appears at the corners of heavy turbine blade castings during heat treatment processes, so a great machining allowance is generally set in production which directly results in cost increase. In this paper, a novel real-time measuring technology is developed for non-contact measuring the deformation behavior of heavy steel castings in heat treatment process. It was employed to measure the distortion and the temperature field of a batch of heavy turbine blade castings at cooling stage in normalizing process. Three inflection points appear in the distortion-time curves, and the residual distortion is affected by the regional area of not finished martensite transformation when the second inflection point appears. When the mean air temperature falls into the range of 10℃-20℃, the residual distortion is small; when it is lower than 10℃, positive distortion appears; when it is higher than 20℃, negative distortion appears. The distortion varies with seasonal temperature, which is directly responsible for the great machining allowance given in production.
