By FENG Benzheng YANG Deqing Institute of Precious Metals
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Kunming
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650221
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Yunnan
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China.Physics Department
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Yunnan University
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Kunming
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China.To whom correspondence should be addressed.
材料科学技术（英）
The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field at room temperature under 10~(-5) Pa vacuum.The results show that the work functions of both glassy alloys are higher than those of the corresponding crystalline alloys.
关键词:
work function
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NING Yuantao Institute of Precious Metals
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Kunming
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China Associate Professor
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Institute of Precious Metals
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Kunming
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Yunnan
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China
金属学报(英文版)
A criterion of the metastable extension of solid solubility was proposed.When the eutectic concentration arm ratio parameter of an alloy,J>10,the hypereutectic extension and the metastable solid solubility limit beyond eutectic concentration may be obtained.When J≤10, the hypoeutectic extension may be obtained.The extension parameter,C_(eq)~s/C_(cu),is directly proportional to the parameter J.Thus,it seems easy to predict the tendency of the solid solu- hility extension under rapid solidification on the basis of the eutectic phase diagram.
关键词:
eutectic system
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NING Yuantao LI Yongnian Kunming Institute of Precious Metals
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Kunmmg
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China Professor
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Kunming Institute of Precious Metals
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Kunming
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Yunnan
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China
金属学报(英文版)
The internal oxidation behavior of Pd-40Ag-1M(M=Zr,Y)alloy wires has been studied in air at 800—1200℃.The relationship between the internal oxidation depth ξ and the reaction time t can be expressed as ξ= Kt~n,where n=0.5—0.75.The higher the temperature,the larger the value of n is.The active elements Zr and Y show different internal oxidation characters.For the alloys eontaining Zr,the oxidation rate along the grain boundaries is about twice as high as that in grains,and“lateral oxidation”exists along the grain boundaries.For the alloys containing Y,the oxidation rates in grains and along the grain boundaries are roughly the same,and there is no“lateral oxidation”along the grain bounda- ries.The activation energies of both alloys are in the range of 120—150kJ/mol.Some prop- erties for oxidized alloys were studied.The mechanisms of the internal oxidation were dis- cussed.
关键词:
Pd-40Ag alloy
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NING Yuantao LI Yongnian Kunming Institute of Precious Metals
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China Ning Yuantao
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Professor
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Institute of Precious Metals
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Kunming
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Yunnan
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China
金属学报(英文版)
The influence of rare-earth elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Ho,Er and Yb on the thermal stability of PdSi_(16.5) glass was studied systematically by means of DSC.All rare-earth elements,especially heavy ones,increase obviously the thermal stability parameters,including T_θ(T_g ,T_x ,T_g),T_(rg) and ΔE etc.The crystallization temperatures T_(p1) and T_(p2) increase linearly with the lanthanide constriction increasing,but Eu shows an anomalous influence:Pd-Si-Eu metallic glass possesses the highest thermal stability and the lowest concentration limit of glass forming among Pd-Si-R glasses.
关键词:
thermal stability
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NING Yuantao ZHOU Xinming DAI Hong Institute of Precious Metals
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Kunming
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Yunnan
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China
金属学报(英文版)
The splat folis of Al-RE(RE=Y,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Er and Yb) binary alloys of 0.04—0.06 mm thickness were made by are-melting and hammer-anvil technique,the.cooling rate is in 10~6 K/s order of magnitude.The metastable extended solid solubilities of these RE elements have been evaluated by measurements of the lattice spacings of the rapidly solidified(RS)Al-RE alloys,they are 0.4,0.15,0.21,0.21,0.3, 0.5,0.1,0.6,0.65,0.7,0.75,0.2 at.-% for above individual RE clements,respectively.The secondary phase in RS Al-RE alloys were identified to be Al_4RE for alloys containing light RE and Eu elements and Al_3 RE for alloys containing heavy RE and Y elements. Some factors influencing the extension of solid solubility of Al-RE alloy were discussed.
关键词:
rapid solidification
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