The specific heat of nanocrystalline iron with grain size of 40nm has been measured in the low temperature range from 1.8 to 26K.The anomalous specific heat behavior of nanocrystalline iron is compared to that of the ...The specific heat of nanocrystalline iron with grain size of 40nm has been measured in the low temperature range from 1.8 to 26K.The anomalous specific heat behavior of nanocrystalline iron is compared to that of the standard bulk iron.It is found that the electronic specific heat coefficientγobtained at low temperatures decreases by about 50%.A T^(2) term in the heat capacity associated with surface modes has been clearly observed.A large enhancement of the specific heat at temperatures above 16K may be interpreted as the Einstein oscillator contributions.展开更多
Amorphization was achieved by a non.equilibrium process of ion mixing of multilayered films iii an inuniscible Fe-Cu system with a large positive heat of formation(+19kJ/mol).The free energy diagrtiin of the Fe-Cu sys...Amorphization was achieved by a non.equilibrium process of ion mixing of multilayered films iii an inuniscible Fe-Cu system with a large positive heat of formation(+19kJ/mol).The free energy diagrtiin of the Fe-Cu system was constructed.In calculation,the inter facial free energy,ferromugnctic effect and the structure ch arac-tenstics were considered.The calculated Fe-Cu free energy diagram can explain the ainorphization behavior in this imniiscible system.展开更多
The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement o...The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (ΔSm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum ΔSm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.展开更多
Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,...Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,accelerometers,force cells,displacement transducers and so forth.The commonly used commercial crystalline strain sensing materials of SGs are in the form of wire or foil of which performance and reliability is not good enough due to their low electrical resistivity and incapacity to get thin thickness.Smaller SGs with single straight strand strain sensing materials,which are called ideal SG,are highly desirable for more than seven decades since the first SG was invented.Here,we show the development of a type of minuscule length scale strain gauge by using a bare and single straight strand metallic glassy fiber(MGF) with high resistivity,much smaller lengthscale,high elastic limits(2.16%) and especially the super piezoresistance effect.We anticipate that our metallic glassy fiber strain gauge(MGFSG),which moves toward the ideal SGs,would have wide applications for electromechanical transducers and stress analysis and catalyze development of more micro-and nanoscale metallic glass applications.展开更多
基金Supported by the National Natural Science Foundation of Chinaspecial funds from State Commission of Science oiid Technologyfrom the Chinese Academy of Sciences.
文摘The specific heat of nanocrystalline iron with grain size of 40nm has been measured in the low temperature range from 1.8 to 26K.The anomalous specific heat behavior of nanocrystalline iron is compared to that of the standard bulk iron.It is found that the electronic specific heat coefficientγobtained at low temperatures decreases by about 50%.A T^(2) term in the heat capacity associated with surface modes has been clearly observed.A large enhancement of the specific heat at temperatures above 16K may be interpreted as the Einstein oscillator contributions.
基金Supported by the National Natural Science Foundation of China。
文摘Amorphization was achieved by a non.equilibrium process of ion mixing of multilayered films iii an inuniscible Fe-Cu system with a large positive heat of formation(+19kJ/mol).The free energy diagrtiin of the Fe-Cu system was constructed.In calculation,the inter facial free energy,ferromugnctic effect and the structure ch arac-tenstics were considered.The calculated Fe-Cu free energy diagram can explain the ainorphization behavior in this imniiscible system.
基金the National Natural Science Foundation of China (Grant Nos. 50621061 and 50731008)the National Basic Research Program of China (973 Program) (Grant No. 2007CB613904)
文摘The magnetocaloric effect (MCE) has made great success in very low temperature refrigeration, which is highly desirable for application to the extended higher tem-perature range. Here we report the giant enhancement of MCE in the metallic glass composite. The large magnetic refrigerant capacity (RC) up to 103 J·kg-1 is more than double the RC of the well-known crystalline magnetic refrigerant compound Gd5Si2Ge1.9Fe0.1 (357 J·kg-1) and MnFeP0.45As0.55 (390 J·kg-1)(containing either ex-orbitant-cost Ge or poisonous As). The full width at half maximum of the magnetic entropy change (ΔSm) peak almost spreads over the whole low-temperature range (from 303 to 30 K), which is five times wider than that of the Gd5Si2Ge1.9Fe0.1 and pure Gd. The maximum ΔSm approaches a nearly constant value in a wide tem-perature span over 100 K, and however, such a broad table-like region near room temperature has seldom been found in alloys and compounds. In combination with the intrinsic amorphous nature, the metallic glass composite may be potential for the ideal Ericsson-cycle magnetic refrigeration over a broad temperature range near room temperature.
基金support from the National Natural Science Foundation of China (Grant Nos. 50921091 and 50731008)the National Basic Research Program of China (973) (Grant Nos. 2007CB613904 and2010CB731603)
文摘Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,accelerometers,force cells,displacement transducers and so forth.The commonly used commercial crystalline strain sensing materials of SGs are in the form of wire or foil of which performance and reliability is not good enough due to their low electrical resistivity and incapacity to get thin thickness.Smaller SGs with single straight strand strain sensing materials,which are called ideal SG,are highly desirable for more than seven decades since the first SG was invented.Here,we show the development of a type of minuscule length scale strain gauge by using a bare and single straight strand metallic glassy fiber(MGF) with high resistivity,much smaller lengthscale,high elastic limits(2.16%) and especially the super piezoresistance effect.We anticipate that our metallic glassy fiber strain gauge(MGFSG),which moves toward the ideal SGs,would have wide applications for electromechanical transducers and stress analysis and catalyze development of more micro-and nanoscale metallic glass applications.
