Ce element was introduced to modify Al−2%Fe(mass fraction)binary alloy.The microstructures,crystallization behavior,electrical/thermal conductivities and mechanical properties of these alloys were systematically inves...Ce element was introduced to modify Al−2%Fe(mass fraction)binary alloy.The microstructures,crystallization behavior,electrical/thermal conductivities and mechanical properties of these alloys were systematically investigated.The results indicated that the appropriate Ce addition decreased the recalescence temperature and growth temperature of Al−Fe eutectic structure,improved the morphology and distribution of Fe-containing phase,and simultaneously increased the conductivity and mechanical properties.The annealed treatment improved the thermal conductivity of these alloys due to the decreasing concentration of point defects.Rolling process further broke up the coarser Fe-containing phases into finer particles and made the secondary phases uniformly distributed in theα(Al)matrix.After subsequent annealing treatment and rolling deformation,the thermal conductivity,ultimate tensile strength and hardness of the Al−2%Fe−0.3%Ce(mass fraction)alloy reached 226 W/(m·K),(182±1.4)MPa and HBW(49.5±1.7),respectively.展开更多
Manuscript received 24 June 1999 The Fe Al P alloy deposits were plated on copper sheets by electroless plating. The change law of the deposition rate, composition, surface appearance and structure for the depo...Manuscript received 24 June 1999 The Fe Al P alloy deposits were plated on copper sheets by electroless plating. The change law of the deposition rate, composition, surface appearance and structure for the deposits was studied by changing the metallic salt ratios (AlCl 3/AlCl 3+FeSO 4), the concentration of metallic salt AlCl 3 and reductant NaH 2PO 2. The optimum plating bath was obtained. It was found that the choices of ligand and reductant were the key of increasing Al content for the deposits.展开更多
The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulati...The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.展开更多
The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial m...The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial mixtures of powders were milled for 100 h in vacuum.The bulk samples were fabricated from the milled powders in a high frequency induction heat sintering(HFIHS)system.The milled powders and the bulk sintered samples were characterized by X-ray diffraction(XRD),Vickers microhardness,field emission scanning electron microscopy(FESEM-EDS)and transmission electron microscopy(TEM).The observations indicated that Fe and Ti were completely dispersed in the matrix to form a supersaturated solid solution(SSSS)with Al.Additionally,the inclusion of alloying elements led to an increase in hardness and yield strength of the alloy by 127%and 152%,respectively.The elevated temperature compression tests were carried out to evaluate the thermal stability of the alloys.The Al−10wt.%Fe−5wt.%Ti alloy revealed the optimum thermally stable behavior of the three alloys studied.The incorporation of Fe and Ti improved the thermal stability of the developed alloys through inhibiting the grain growth,hindering dissolution and growth of second phases(such as Al13Fe4 and Al13Ti),and forming a stable solid solution.展开更多
Time dependent nucleation theory was applied to calculate the incubation time required for α Al nucleation in rapid solidified (RS) Al Fe V Si Nd alloys. The nucleation rates were calculated as a function of tem...Time dependent nucleation theory was applied to calculate the incubation time required for α Al nucleation in rapid solidified (RS) Al Fe V Si Nd alloys. The nucleation rates were calculated as a function of temperature, and the critical cooling rates required for the formation of amorphous α Al at different neodymium concentrations were calculated too. The addition of neodymium increases the amorphizablity of α Al by increasing the incubation time and decreasing the nucleation rate and the critical cooling rate. The calculations are fitted to experimental results when liquidus temperatures are estimated from an approximation, which treats Al Fe V Si Nd as quasi binary Al Fe system.展开更多
Ultra high vacuum gaseous hydrogen permeation experiments on Fe 3Al based alloy were performed in the temperature range of 330～450℃ with an upstream hydrogen pressure between 3.38×10 4 Pa and 7.28×10 4 Pa...Ultra high vacuum gaseous hydrogen permeation experiments on Fe 3Al based alloy were performed in the temperature range of 330～450℃ with an upstream hydrogen pressure between 3.38×10 4 Pa and 7.28×10 4 Pa. The results show that the hydrogen diffusivity and permeability in Fe 3Al based alloy obey Arrhenius relationship in the experimental temperature range and the hydrogen permeation process is controlled by the lattice diffusion of hydrogen at relative high temperature. The activation energy of hydrogen diffusion in the Fe 3Al based alloy was found to be 75 kJ/mol.展开更多
Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resista...Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resistance ofthe as-welded Cu12Mn8Al3Fe2Ni alloy is much more superior to that of the as-cast one. The cumulative mass lossand the mass loss rate of the as-welded Cu12Mn8Al3Fe2Ni alloy are almost 1/4 that of the as-cast one. SEM analysisof eroded specimens reveals that the as-cast Cu12Mn8Al3Fe2Ni alloy is attacked more severely than the as-weldedone. Microcracks causing cavitation damage initiate at the phase boundaries.展开更多
The mechanism of iron and aluminum intermetallics formation in the reactive sintering of iron and aluminum mixing powders has been studied by investigating iron aluminum diffusion couples.The couples were treated at ...The mechanism of iron and aluminum intermetallics formation in the reactive sintering of iron and aluminum mixing powders has been studied by investigating iron aluminum diffusion couples.The couples were treated at 600℃,700℃,800℃,900℃ and 1000℃ respectively.It was found that an Al rich intermetallics FeAl 3 has formed in iron adjacent to the interface of iron and aluminum by aluminum diffusion into iron at 600℃ (below the eutectic temperature),and that in the case above 700℃ (above the eutectic temperature) there was a liquid,an intermetallics Fe 2Al 5 has formed in both side of the interface.The diffusion of iron and aluminum atoms is companied with the Fe Al reaction during the treatment under the both conditions.The diffusion coefficients of iron and aluminum and the activation energy were determined.The mechanism of the intermetallics formation in the couples is also discussed.展开更多
Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si（wt%）. The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits...Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si（wt%）. The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12（Fe,V）3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 ℃ resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12（Fe, V）3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 k J/mol. A more homogenous microstructure was obtained after annealing at 400 °C for 60 min,which was resistant to coarsening exposed at 425 °C up to 500 h. The Al12（Fe,V）3Si and AlmF e phases were coarsened at 475 and 525℃ with increasing the exposure time. Coarsening of Al12（Fe,V）3Si phase was attributed to a combination of volume diffusion and grain boundary diffusion mechanism of Fe. Heat treatment at 600℃ resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi？cantly degraded the room temperature microhardness.展开更多
Tribological behavior of nanostructured pure Al and Al–Al12（Fe,V）3Si alloys containing 27（FVS0812） and 37（FVS1212） vol% of Al12（Fe,V）3Si precipitates was investigated. All samples were prepared using mechanic...Tribological behavior of nanostructured pure Al and Al–Al12（Fe,V）3Si alloys containing 27（FVS0812） and 37（FVS1212） vol% of Al12（Fe,V）3Si precipitates was investigated. All samples were prepared using mechanical alloying followed by hot pressing. Wear tests were performed at room temperature using a pin-on-disk machine. Results showed that the presence of Al12（Fe,V）3Si precipitates increases the wear resistance of nanostructured Al, and the wear resistance increases with increasing the Al12（Fe,V）3Si content. Scanning electron microscopy images of worn surfaces and wear debris demonstrated that abrasion and adhesion are the governing wear mechanisms for the nanostructured FVS0812 alloy at 2 and 5 N normal loads, whereas for the nanostructured FVS1212 alloy, the dominant wear mechanism is abrasion at these loads. A mechanically mixed layer（MML） containing Fe and O was formed on the worn surfaces of FVS0812 and FVS1212 samples at 10 N normal load. Formation and delamination of MML controls the wear behavior of these samples at the normal load of 10 N. It is also found that the presence of Al12（Fe,V）3Si precipitates decreases the friction coefficient of nanostructured Al.展开更多
An ultrasonic vibration-assisted air-cooled stirring rod process(ACSR+UV)was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg.A low-cost Al–Si–Fe–Mg–Cu–Zn die-casted allo...An ultrasonic vibration-assisted air-cooled stirring rod process(ACSR+UV)was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg.A low-cost Al–Si–Fe–Mg–Cu–Zn die-casted alloy with high thermal conductivity,high plasticity and medium strength was developed.The alloy was used to manufacture large,thin-walled parts for 5 G base stations by using the ACSR+UV rheological die-casting(ACSR+UV R-DC)process.Investigations were performed on the microstructure,porosity,mechanical properties,fracture behaviour and thermal conductivity of the ACSR+UV R-DC alloy,which was then compared to traditionally die-casted(T-DC)and ACSR R-DC alloys.The mechanisms for the microstructural refinement and enhancement of the mechanical and thermal conductivity performances of the ACSR+UV R-DC alloy were also analysed.The results showed that the ACSR+UV process increased the nucleation rate of the melt due to the increase in the nucleation area and the generation of cavitation bubbles.A radial-and an axial-forced convection was also generated inside the melt under the combined effects of acoustic flow and mechanical stirring,thereby homogenising the melt composition field and the temperature field.Therefore,the ACSR+UV R-DC process not only refined the primaryα-Al(α_(1)-Al),the eutectic silicon and the secondaryα-Al(α_(2)-Al),but also greatly improved the morphology and the distribution of the β-Al5FeSi phase.The mechanical properties of the ACSR+UV R-DC alloy were higher than those of the T-DC and the ACSR R-DC alloys.Compared to the T-DC alloy,the ultimate tensile strength,elongation and yield strength of the ACSR+UV R-DC alloy were increased by 34%,122%and 19%,respectively.This was because the ACSR+UV R-DC technique gave the alloy the characteristics of high density,fine sphericalα1-Al grain and a fine and uniform β-phase,which improved the fracture behaviour of the alloy.The thermal conductivity of the ACSR+UV R-DC alloy was 184 W/(m K),which was 10.2%and 3.4%higher than that of T-DC and ACSR R-DC alloys,respectively.This was because the refined eutectic silicon and β phases in the ACSR+UV R-DC alloy facilitated an easier electron flow through the eutectic region,and the decrease in porosity increased the effective area of heat conduction.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52174363)the GDAS Project of Science and Technology Development,China(No.2019GDASYL-0203002)+2 种基金the Key Research and Development Program of Guangdong Province,China(No.2020B010186002)the Science and Technology Project of Zhaoqing City,China(Nos.2021C003,2018K006)the Development of Key Technologies for Material and Microstructure Control of High Thermal Conductivity Casting Aluminum Alloy,China(No.2014A030313221)。
文摘Ce element was introduced to modify Al−2%Fe(mass fraction)binary alloy.The microstructures,crystallization behavior,electrical/thermal conductivities and mechanical properties of these alloys were systematically investigated.The results indicated that the appropriate Ce addition decreased the recalescence temperature and growth temperature of Al−Fe eutectic structure,improved the morphology and distribution of Fe-containing phase,and simultaneously increased the conductivity and mechanical properties.The annealed treatment improved the thermal conductivity of these alloys due to the decreasing concentration of point defects.Rolling process further broke up the coarser Fe-containing phases into finer particles and made the secondary phases uniformly distributed in theα(Al)matrix.After subsequent annealing treatment and rolling deformation,the thermal conductivity,ultimate tensile strength and hardness of the Al−2%Fe−0.3%Ce(mass fraction)alloy reached 226 W/(m·K),(182±1.4)MPa and HBW(49.5±1.7),respectively.
文摘Manuscript received 24 June 1999 The Fe Al P alloy deposits were plated on copper sheets by electroless plating. The change law of the deposition rate, composition, surface appearance and structure for the deposits was studied by changing the metallic salt ratios (AlCl 3/AlCl 3+FeSO 4), the concentration of metallic salt AlCl 3 and reductant NaH 2PO 2. The optimum plating bath was obtained. It was found that the choices of ligand and reductant were the key of increasing Al content for the deposits.
基金Project supported by the National Magnetic Confinement Fusion Energy Research Project(Grant Nos.2019YFE03120003,2018YFE0307100,and 2017YFE0302500)the National Natural Science Foundation of China(Grant Nos.11975034,11921006,12004010,and U20B2025).
文摘The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.
文摘The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated.Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated.The initial mixtures of powders were milled for 100 h in vacuum.The bulk samples were fabricated from the milled powders in a high frequency induction heat sintering(HFIHS)system.The milled powders and the bulk sintered samples were characterized by X-ray diffraction(XRD),Vickers microhardness,field emission scanning electron microscopy(FESEM-EDS)and transmission electron microscopy(TEM).The observations indicated that Fe and Ti were completely dispersed in the matrix to form a supersaturated solid solution(SSSS)with Al.Additionally,the inclusion of alloying elements led to an increase in hardness and yield strength of the alloy by 127%and 152%,respectively.The elevated temperature compression tests were carried out to evaluate the thermal stability of the alloys.The Al−10wt.%Fe−5wt.%Ti alloy revealed the optimum thermally stable behavior of the three alloys studied.The incorporation of Fe and Ti improved the thermal stability of the developed alloys through inhibiting the grain growth,hindering dissolution and growth of second phases(such as Al13Fe4 and Al13Ti),and forming a stable solid solution.
基金Project supported by the National Natural Science Foundation of China(55791020)
文摘Time dependent nucleation theory was applied to calculate the incubation time required for α Al nucleation in rapid solidified (RS) Al Fe V Si Nd alloys. The nucleation rates were calculated as a function of temperature, and the critical cooling rates required for the formation of amorphous α Al at different neodymium concentrations were calculated too. The addition of neodymium increases the amorphizablity of α Al by increasing the incubation time and decreasing the nucleation rate and the critical cooling rate. The calculations are fitted to experimental results when liquidus temperatures are estimated from an approximation, which treats Al Fe V Si Nd as quasi binary Al Fe system.
基金Supported by the National Natural Science Foundation of China!( 5 9895 1 5 7)
文摘Ultra high vacuum gaseous hydrogen permeation experiments on Fe 3Al based alloy were performed in the temperature range of 330～450℃ with an upstream hydrogen pressure between 3.38×10 4 Pa and 7.28×10 4 Pa. The results show that the hydrogen diffusivity and permeability in Fe 3Al based alloy obey Arrhenius relationship in the experimental temperature range and the hydrogen permeation process is controlled by the lattice diffusion of hydrogen at relative high temperature. The activation energy of hydrogen diffusion in the Fe 3Al based alloy was found to be 75 kJ/mol.
文摘Cavitation erosion behavior of as-welded Cu12Mn8Al3Fe2Ni alloy in 3.5% NaCl aqueous solution was studied bymagnetostrictive vibratory device for cavitation erosion. The results show that the cavitation erosion resistance ofthe as-welded Cu12Mn8Al3Fe2Ni alloy is much more superior to that of the as-cast one. The cumulative mass lossand the mass loss rate of the as-welded Cu12Mn8Al3Fe2Ni alloy are almost 1/4 that of the as-cast one. SEM analysisof eroded specimens reveals that the as-cast Cu12Mn8Al3Fe2Ni alloy is attacked more severely than the as-weldedone. Microcracks causing cavitation damage initiate at the phase boundaries.
文摘The mechanism of iron and aluminum intermetallics formation in the reactive sintering of iron and aluminum mixing powders has been studied by investigating iron aluminum diffusion couples.The couples were treated at 600℃,700℃,800℃,900℃ and 1000℃ respectively.It was found that an Al rich intermetallics FeAl 3 has formed in iron adjacent to the interface of iron and aluminum by aluminum diffusion into iron at 600℃ (below the eutectic temperature),and that in the case above 700℃ (above the eutectic temperature) there was a liquid,an intermetallics Fe 2Al 5 has formed in both side of the interface.The diffusion of iron and aluminum atoms is companied with the Fe Al reaction during the treatment under the both conditions.The diffusion coefficients of iron and aluminum and the activation energy were determined.The mechanism of the intermetallics formation in the couples is also discussed.
基金support of the National High Technology Research and Development Program of China("863 Program",Grant No.21100002013101006)
文摘Selective laser melting was used to produce an aluminum alloy Al-8.5Fe-1.3V-1.7Si（wt%）. The effects of heat treatment on microstructure evolution and phase stability during long-term thermal exposure of the deposits were investigated. Results show that the microquasi-crystalline phase, Al12（Fe,V）3Si and AlmF e metastable phases coexisted with α-Al in the as-produced alloy. Annealing at 400 ℃ resulted in decomposition of microquasi-crystalline phase and supersaturated α-Al into Al12（Fe, V）3Si phase in the fusion zone, accompanied by the decrease in alloy hardness. The activation energy of this decomposition process was 115 k J/mol. A more homogenous microstructure was obtained after annealing at 400 °C for 60 min,which was resistant to coarsening exposed at 425 °C up to 500 h. The Al12（Fe,V）3Si and AlmF e phases were coarsened at 475 and 525℃ with increasing the exposure time. Coarsening of Al12（Fe,V）3Si phase was attributed to a combination of volume diffusion and grain boundary diffusion mechanism of Fe. Heat treatment at 600℃ resulted in accelerated microstructure coarsening and formation of large-sized equilibrium phases, which signi？cantly degraded the room temperature microhardness.
文摘Tribological behavior of nanostructured pure Al and Al–Al12（Fe,V）3Si alloys containing 27（FVS0812） and 37（FVS1212） vol% of Al12（Fe,V）3Si precipitates was investigated. All samples were prepared using mechanical alloying followed by hot pressing. Wear tests were performed at room temperature using a pin-on-disk machine. Results showed that the presence of Al12（Fe,V）3Si precipitates increases the wear resistance of nanostructured Al, and the wear resistance increases with increasing the Al12（Fe,V）3Si content. Scanning electron microscopy images of worn surfaces and wear debris demonstrated that abrasion and adhesion are the governing wear mechanisms for the nanostructured FVS0812 alloy at 2 and 5 N normal loads, whereas for the nanostructured FVS1212 alloy, the dominant wear mechanism is abrasion at these loads. A mechanically mixed layer（MML） containing Fe and O was formed on the worn surfaces of FVS0812 and FVS1212 samples at 10 N normal load. Formation and delamination of MML controls the wear behavior of these samples at the normal load of 10 N. It is also found that the presence of Al12（Fe,V）3Si precipitates decreases the friction coefficient of nanostructured Al.
基金the National Natural Science Foundation of China(Nos.52005034 and 52027805)the Fundamental Research Funds for the Central Universities(No.FRF-TP-18-043A1)+1 种基金the Zhuhai Industry-University-Research Cooperation Project(No.ZH22017001200176PWC)the China Postdoctoral Science Foundation Funded Project(No.2019M650486)。
文摘An ultrasonic vibration-assisted air-cooled stirring rod process(ACSR+UV)was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg.A low-cost Al–Si–Fe–Mg–Cu–Zn die-casted alloy with high thermal conductivity,high plasticity and medium strength was developed.The alloy was used to manufacture large,thin-walled parts for 5 G base stations by using the ACSR+UV rheological die-casting(ACSR+UV R-DC)process.Investigations were performed on the microstructure,porosity,mechanical properties,fracture behaviour and thermal conductivity of the ACSR+UV R-DC alloy,which was then compared to traditionally die-casted(T-DC)and ACSR R-DC alloys.The mechanisms for the microstructural refinement and enhancement of the mechanical and thermal conductivity performances of the ACSR+UV R-DC alloy were also analysed.The results showed that the ACSR+UV process increased the nucleation rate of the melt due to the increase in the nucleation area and the generation of cavitation bubbles.A radial-and an axial-forced convection was also generated inside the melt under the combined effects of acoustic flow and mechanical stirring,thereby homogenising the melt composition field and the temperature field.Therefore,the ACSR+UV R-DC process not only refined the primaryα-Al(α_(1)-Al),the eutectic silicon and the secondaryα-Al(α_(2)-Al),but also greatly improved the morphology and the distribution of the β-Al5FeSi phase.The mechanical properties of the ACSR+UV R-DC alloy were higher than those of the T-DC and the ACSR R-DC alloys.Compared to the T-DC alloy,the ultimate tensile strength,elongation and yield strength of the ACSR+UV R-DC alloy were increased by 34%,122%and 19%,respectively.This was because the ACSR+UV R-DC technique gave the alloy the characteristics of high density,fine sphericalα1-Al grain and a fine and uniform β-phase,which improved the fracture behaviour of the alloy.The thermal conductivity of the ACSR+UV R-DC alloy was 184 W/(m K),which was 10.2%and 3.4%higher than that of T-DC and ACSR R-DC alloys,respectively.This was because the refined eutectic silicon and β phases in the ACSR+UV R-DC alloy facilitated an easier electron flow through the eutectic region,and the decrease in porosity increased the effective area of heat conduction.
