The recrystallization behavior of Mo wires doped with various contents of La2O3,which were prepared by powder metallurgy method,was investigated using TEM and SEM in detail.It is shown that the recrystallization tempe...The recrystallization behavior of Mo wires doped with various contents of La2O3,which were prepared by powder metallurgy method,was investigated using TEM and SEM in detail.It is shown that the recrystallization temperature and recrystallized microstructure of Mo-La2O3 wires are strongly dependent on the La2O3 contents.An interlocked large grain structure is formed in Mo-La2O3 wires with contents of 0.2-0.4 wt% La2O3,on the other hand,Mo─La2O3 wires containing less than 0.1 or more than 0.8 wt% La2O3 show equiaxed grain structure.The reason for this is the difference between the longitudinal interparticle spacing and the transverse spacing of La2O3 particles in various Mo-La2O3 wires,which was observed by using TEM.展开更多
Ultrafine-grained WC-Co bulk materials were prepared by a new method that contains pretreatment of the milled powder mixture and subsequent spark plasma sintering （SPS）. Ball milling parameters and the pretreatment ...Ultrafine-grained WC-Co bulk materials were prepared by a new method that contains pretreatment of the milled powder mixture and subsequent spark plasma sintering （SPS）. Ball milling parameters and the pretreatment temperature have significant effects on the microstructure and properties of WC-Co cermets. The prepared cermets have a mean grain size of less than 0.5 μm even with a pretreatment temperature as high as 1300℃. The WC-10wt.%Co cermet bulk prepared by the optimized milling, pretreatment, and SPS processing achieves excellent mechanical properties with a Vickers hardness of HV 1643, a fracture toughness of 13.1 MPa.m^1/2 and a transverse rapture strength of 3100 MPa.展开更多
Bulk CoSb3 with single phase was synthesized by mechanical alloying and spark plasma sintering （MA-SPS）. The thermoelectric properties of bulk CoSb3 prepared by different technologies were investigated. All samples ...Bulk CoSb3 with single phase was synthesized by mechanical alloying and spark plasma sintering （MA-SPS）. The thermoelectric properties of bulk CoSb3 prepared by different technologies were investigated. All samples have the character of typical semiconductor electricity and their thermoelectric figures of merit （ZT） get the maximum values at 400℃. The highest ZT value is 0.0571, belonging to the sample sintered at 600℃ among all samples at all temperatures.展开更多
Mo-5Ta targets were prepared by the spark plasma sintering(SPS)technology under the sintering temperatures of 1400-1600℃,the holding times of 0-20 min,and the axial pressure of 30 MPa.The microstructure,performance,a...Mo-5Ta targets were prepared by the spark plasma sintering(SPS)technology under the sintering temperatures of 1400-1600℃,the holding times of 0-20 min,and the axial pressure of 30 MPa.The microstructure,performance,and grain growth kinetics of Mo-5Ta sputtering targets were studied.With the increase of sintering temperatures and times,Ta can more dissolve in Mo and form a Mo(Ta)solid solution.The grain sizes of Mo-5Ta targets remain unchanged at low temperatures(1400-1500℃)while increasing significantly at high temperature(1600℃)with the extension of the holding time.In addition,the densities and Vickers hardness(HV_(0.5))first ascend and then decrease with sintering proceeding.The thermal conductivity is positively correlated with the grain size and density,as a result of their joint action.Based on the comprehensive analysis,the grain growth is dominated by the combination of boundary diffusion and volume diffusion.When n=2,the activation energies of grain growth under holding times of 5,10,20 min are calculated as 762.70,617.86,and 616.52 kJ/mol,respectively.展开更多
The magneto-caloric effect of Gd5 Si2Ge2 compounds produced by various techniques is investigated in terms of their magnetization behaviors in the magnetic field from 0 to 2.0 T.The studied materials include arc-melte...The magneto-caloric effect of Gd5 Si2Ge2 compounds produced by various techniques is investigated in terms of their magnetization behaviors in the magnetic field from 0 to 2.0 T.The studied materials include arc-melted, annealed and sintered alloys.The results demonstrate that the Gd5Si2Ge2 alloys obtained under different processing conditions possess distinct magneto-caloric effect due to their various microstructures.Proper annealing treatment can enhance the magneto-caloric effect of the alloy remarkably.While the sintered alloy bears relatively lower value of magnetic entropy change ( △ SM) than arc-melted one.The magnetic entropy change of the annealed Gd5 Si2Ge2 alloy arrives the arrives the maximum value of - △SM = 15.29 J· kg-1· K-1 for magnetic field change under 2.0 T in the present work.展开更多
High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decompo...High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decomposition dynamic of the magnets were investigated.It is found that higher sintering temperature improves the densification of the magnets, while deteriorates their magnetic properties simultaneously due to the decomposition of the Sm2Fe17Nx.Sintering at lower temperature can preserve the crystal structure of Sm2Fe17Nx compound, while the powders cannot be consolidated into a fully dense compact.An increased compressive pressure leads to better magnetic properties and higher density for the magnet at the same sintering temperature.展开更多
文摘The recrystallization behavior of Mo wires doped with various contents of La2O3,which were prepared by powder metallurgy method,was investigated using TEM and SEM in detail.It is shown that the recrystallization temperature and recrystallized microstructure of Mo-La2O3 wires are strongly dependent on the La2O3 contents.An interlocked large grain structure is formed in Mo-La2O3 wires with contents of 0.2-0.4 wt% La2O3,on the other hand,Mo─La2O3 wires containing less than 0.1 or more than 0.8 wt% La2O3 show equiaxed grain structure.The reason for this is the difference between the longitudinal interparticle spacing and the transverse spacing of La2O3 particles in various Mo-La2O3 wires,which was observed by using TEM.
基金supported by the National Natural Science Foundation of China (Nos. 50401001 and 50671001) the Program for New Century Excellent Talents in Universities of China (No. NCET-06-0182)
文摘Ultrafine-grained WC-Co bulk materials were prepared by a new method that contains pretreatment of the milled powder mixture and subsequent spark plasma sintering （SPS）. Ball milling parameters and the pretreatment temperature have significant effects on the microstructure and properties of WC-Co cermets. The prepared cermets have a mean grain size of less than 0.5 μm even with a pretreatment temperature as high as 1300℃. The WC-10wt.%Co cermet bulk prepared by the optimized milling, pretreatment, and SPS processing achieves excellent mechanical properties with a Vickers hardness of HV 1643, a fracture toughness of 13.1 MPa.m^1/2 and a transverse rapture strength of 3100 MPa.
文摘Bulk CoSb3 with single phase was synthesized by mechanical alloying and spark plasma sintering （MA-SPS）. The thermoelectric properties of bulk CoSb3 prepared by different technologies were investigated. All samples have the character of typical semiconductor electricity and their thermoelectric figures of merit （ZT） get the maximum values at 400℃. The highest ZT value is 0.0571, belonging to the sample sintered at 600℃ among all samples at all temperatures.
基金“Solid Waste Recycling”Key Project of National Key R&D Plan of China(No.2018YFC1901700)the Fundamental Research Funds for the Central Universities of China(Nos.JZ2021HGTB0094 and PA2021GDGP0059)。
文摘Mo-5Ta targets were prepared by the spark plasma sintering(SPS)technology under the sintering temperatures of 1400-1600℃,the holding times of 0-20 min,and the axial pressure of 30 MPa.The microstructure,performance,and grain growth kinetics of Mo-5Ta sputtering targets were studied.With the increase of sintering temperatures and times,Ta can more dissolve in Mo and form a Mo(Ta)solid solution.The grain sizes of Mo-5Ta targets remain unchanged at low temperatures(1400-1500℃)while increasing significantly at high temperature(1600℃)with the extension of the holding time.In addition,the densities and Vickers hardness(HV_(0.5))first ascend and then decrease with sintering proceeding.The thermal conductivity is positively correlated with the grain size and density,as a result of their joint action.Based on the comprehensive analysis,the grain growth is dominated by the combination of boundary diffusion and volume diffusion.When n=2,the activation energies of grain growth under holding times of 5,10,20 min are calculated as 762.70,617.86,and 616.52 kJ/mol,respectively.
文摘The magneto-caloric effect of Gd5 Si2Ge2 compounds produced by various techniques is investigated in terms of their magnetization behaviors in the magnetic field from 0 to 2.0 T.The studied materials include arc-melted, annealed and sintered alloys.The results demonstrate that the Gd5Si2Ge2 alloys obtained under different processing conditions possess distinct magneto-caloric effect due to their various microstructures.Proper annealing treatment can enhance the magneto-caloric effect of the alloy remarkably.While the sintered alloy bears relatively lower value of magnetic entropy change ( △ SM) than arc-melted one.The magnetic entropy change of the annealed Gd5 Si2Ge2 alloy arrives the arrives the maximum value of - △SM = 15.29 J· kg-1· K-1 for magnetic field change under 2.0 T in the present work.
文摘High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decomposition dynamic of the magnets were investigated.It is found that higher sintering temperature improves the densification of the magnets, while deteriorates their magnetic properties simultaneously due to the decomposition of the Sm2Fe17Nx.Sintering at lower temperature can preserve the crystal structure of Sm2Fe17Nx compound, while the powders cannot be consolidated into a fully dense compact.An increased compressive pressure leads to better magnetic properties and higher density for the magnet at the same sintering temperature.
