The temperature,duration,activation energy,and Avrami exponent of the solid phase transformationβ_(1)→α+β_(2) of TC4 titanium alloy treated at 3 GPa in a cooling process are calculated by means of differential sca...The temperature,duration,activation energy,and Avrami exponent of the solid phase transformationβ_(1)→α+β_(2) of TC4 titanium alloy treated at 3 GPa in a cooling process are calculated by means of differential scanning calorimetric curves.Then the effects of high pressure on theβ_(1)→α+β_(2) phase transformation dynamics of TC4 alloy in a cooling process are investigated.The results show that 3 GPa high pressure treatment can increase the activation energy of the TC4 alloy.The beginning time,end time,and duration of theβ_(1)→α+β_(2) phase transition of the 3 GPa high pressure treated TC4 alloy at the cooling rate of 10℃/min are increased by 2.90℃,7.78℃ and-29.28 s respectively.It is known that 3 GPa high pressure treatment has little effect on the phase transition mechanism.展开更多
The high-pressure behaviour of the superconductor MgB_(2) with a hexagonal structure has been investigated by the in situ synchrotron radiation x-ray diffraction method under pressures up to 42.2 GPa in a diamond anvi...The high-pressure behaviour of the superconductor MgB_(2) with a hexagonal structure has been investigated by the in situ synchrotron radiation x-ray diffraction method under pressures up to 42.2 GPa in a diamond anvil cell. An abrupt decrease of about 7% in the unit cell volume of this material occurs in the pressure range of 26.3-30.2 GPa. A split of the Raman spectrum was also observed. The jump of the compression curve and Raman spectrum are ascribed to an isostructural transition in MgB_(2 ) at a pressure of 30.2 GPa.展开更多
The Pd_(39)Ni_(10)Cu_(30)P_(21) bulk metallic glass is isothermally relaxed under various pressures.The degree of the structural relaxation is evaluated in terms of the enthalpy recovery behaviours involved in the irr...The Pd_(39)Ni_(10)Cu_(30)P_(21) bulk metallic glass is isothermally relaxed under various pressures.The degree of the structural relaxation is evaluated in terms of the enthalpy recovery behaviours involved in the irreversible glass transition processes by using a temperature-modulated differential scanning calarimetry technique.A roughly linear increase of the recovery enthalpy is observed within the experimental pressure range from 2.67 to 4.45 GPa,which reflects the release of the frozen-in enthalpy in the as-quenched glass with increasing relaxation pressure.The pressure dependence of the time scale of the enthalpy recovery processes is also exhibited.展开更多
Single crystals ofβ–FeSi_(2) have been grown from vapor by employing chemical vapor transport technique and using iodine as transport agent in a closed ampoule.In the experiment,β–FeSi_(2) single crystals with wel...Single crystals ofβ–FeSi_(2) have been grown from vapor by employing chemical vapor transport technique and using iodine as transport agent in a closed ampoule.In the experiment,β–FeSi_(2) single crystals with well-developed faces and edges have been observed on the silicon substrate,but no needlelike ones have been found.The changes in the size and the geometric shape of the growth ampoule and temperature gradient are primary factors which result in the variation on β–FeSi_(2) single crystal morphology.展开更多
Undercooled melt of Ge_(73.7)Ni_(26.3) alloy sample floated on B_(2)O_(3 ) melt was subjected to sputtering-deposition of Ni clusters on cooling to induce solidification.The initial temperature of solidification was 9...Undercooled melt of Ge_(73.7)Ni_(26.3) alloy sample floated on B_(2)O_(3 ) melt was subjected to sputtering-deposition of Ni clusters on cooling to induce solidification.The initial temperature of solidification was 975 K.Its undercoolingΔT was 134 K with respect to the melting temperature of the primary phase Ge.On the cooling curve existed dual recalescences representing the transformation of the primary phase(Ge)and the eutectics(Ge+GeNi)respectively.But for the sample unsputtered,only a single exothermic peak presented on the cooling curve with the initial solidification temperature of 904K and undercooling of 205K.Careful observation of the microstructure proved that the Ge phase primarily formed in the sputtering experiment was now formed together with the formation of the eutectics in the experiment without sputtering.展开更多
The in situ four-point probe resistivity measurement was used as a main method to study the solid/liquid interfacial characteristics in Ag/Sn/Ag trilayers at temperatures ranging from 150 to 305℃.It is found from the...The in situ four-point probe resistivity measurement was used as a main method to study the solid/liquid interfacial characteristics in Ag/Sn/Ag trilayers at temperatures ranging from 150 to 305℃.It is found from the variation of resistivity that three processes take place on annealing:the dissolution of silver atoms,the diffusion of silver atoms,and the formation of Ag3Sn in liquid tin layer.The first one plays the leading role in the variation of resistivity during annealing process.The apparent diffusivity of silver in liquid tin at 305℃ is determined to be 7.3×10^(-17)cm^(2)/s.展开更多
Hypervelocity impact on rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass(BMG)is performed by a two−stage light gas gun.The targets used in the experiment are BMG plates with a thickness of 5 mm.Th...Hypervelocity impact on rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass(BMG)is performed by a two−stage light gas gun.The targets used in the experiment are BMG plates with a thickness of 5 mm.The projectile,spherical aluminum(3.1 mm in diameter),is accelerated up to various velocities;the light is detected with a radiometer.The emission lasts from 200µs up to 1500µs and the intensity increases from 44 to 900 W/(Sr⋅µm).The duration and intensity of a light emission seem to depend on the impact velocity and the extent of target destruction through the formation of impact craters or penetration.展开更多
文摘The temperature,duration,activation energy,and Avrami exponent of the solid phase transformationβ_(1)→α+β_(2) of TC4 titanium alloy treated at 3 GPa in a cooling process are calculated by means of differential scanning calorimetric curves.Then the effects of high pressure on theβ_(1)→α+β_(2) phase transformation dynamics of TC4 alloy in a cooling process are investigated.The results show that 3 GPa high pressure treatment can increase the activation energy of the TC4 alloy.The beginning time,end time,and duration of theβ_(1)→α+β_(2) phase transition of the 3 GPa high pressure treated TC4 alloy at the cooling rate of 10℃/min are increased by 2.90℃,7.78℃ and-29.28 s respectively.It is known that 3 GPa high pressure treatment has little effect on the phase transition mechanism.
基金Supported by the National Natural Science Foundation of China under Grant No.10004014the synchrotron radiation experiments were carried out under Approval No.2001PF-03 of the Photon Factory.
文摘The high-pressure behaviour of the superconductor MgB_(2) with a hexagonal structure has been investigated by the in situ synchrotron radiation x-ray diffraction method under pressures up to 42.2 GPa in a diamond anvil cell. An abrupt decrease of about 7% in the unit cell volume of this material occurs in the pressure range of 26.3-30.2 GPa. A split of the Raman spectrum was also observed. The jump of the compression curve and Raman spectrum are ascribed to an isostructural transition in MgB_(2 ) at a pressure of 30.2 GPa.
基金Supported by the National Natural Science Foundation of China under Grant Nos.59889102,10004014by Chinese National Microgravity Laboratory(Pan-Yu-95-34).
文摘The Pd_(39)Ni_(10)Cu_(30)P_(21) bulk metallic glass is isothermally relaxed under various pressures.The degree of the structural relaxation is evaluated in terms of the enthalpy recovery behaviours involved in the irreversible glass transition processes by using a temperature-modulated differential scanning calarimetry technique.A roughly linear increase of the recovery enthalpy is observed within the experimental pressure range from 2.67 to 4.45 GPa,which reflects the release of the frozen-in enthalpy in the as-quenched glass with increasing relaxation pressure.The pressure dependence of the time scale of the enthalpy recovery processes is also exhibited.
基金Supported by the National Natural Science Foundation of China under Grant No.59889102.
文摘Single crystals ofβ–FeSi_(2) have been grown from vapor by employing chemical vapor transport technique and using iodine as transport agent in a closed ampoule.In the experiment,β–FeSi_(2) single crystals with well-developed faces and edges have been observed on the silicon substrate,but no needlelike ones have been found.The changes in the size and the geometric shape of the growth ampoule and temperature gradient are primary factors which result in the variation on β–FeSi_(2) single crystal morphology.
文摘Undercooled melt of Ge_(73.7)Ni_(26.3) alloy sample floated on B_(2)O_(3 ) melt was subjected to sputtering-deposition of Ni clusters on cooling to induce solidification.The initial temperature of solidification was 975 K.Its undercoolingΔT was 134 K with respect to the melting temperature of the primary phase Ge.On the cooling curve existed dual recalescences representing the transformation of the primary phase(Ge)and the eutectics(Ge+GeNi)respectively.But for the sample unsputtered,only a single exothermic peak presented on the cooling curve with the initial solidification temperature of 904K and undercooling of 205K.Careful observation of the microstructure proved that the Ge phase primarily formed in the sputtering experiment was now formed together with the formation of the eutectics in the experiment without sputtering.
文摘The in situ four-point probe resistivity measurement was used as a main method to study the solid/liquid interfacial characteristics in Ag/Sn/Ag trilayers at temperatures ranging from 150 to 305℃.It is found from the variation of resistivity that three processes take place on annealing:the dissolution of silver atoms,the diffusion of silver atoms,and the formation of Ag3Sn in liquid tin layer.The first one plays the leading role in the variation of resistivity during annealing process.The apparent diffusivity of silver in liquid tin at 305℃ is determined to be 7.3×10^(-17)cm^(2)/s.
基金by the National Basic Research Program of China(973 Program)under Grant No 2010CB731600.
文摘Hypervelocity impact on rectangular plate-shaped Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass(BMG)is performed by a two−stage light gas gun.The targets used in the experiment are BMG plates with a thickness of 5 mm.The projectile,spherical aluminum(3.1 mm in diameter),is accelerated up to various velocities;the light is detected with a radiometer.The emission lasts from 200µs up to 1500µs and the intensity increases from 44 to 900 W/(Sr⋅µm).The duration and intensity of a light emission seem to depend on the impact velocity and the extent of target destruction through the formation of impact craters or penetration.
