The effect of heat treatment on martensitic transformation behavior has been investigated in Ti44Ni47Nb9 alloy. The relation between transformation temperatures and critical stress of stress induced martensitic transf...The effect of heat treatment on martensitic transformation behavior has been investigated in Ti44Ni47Nb9 alloy. The relation between transformation temperatures and critical stress of stress induced martensitic transformation is interpreted in terms of thermodynamic theory. It is shown that the decrease in transformation temperature in specimens of slow cooling rate or low temperature aging after solution heat treatment results from the changes of Ni/Ti ratio in the matrix. The increase of critical stress of stress induced martensitic transformation is a consequence of the decrease of transformation temperatures.展开更多
Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load‐carrying capability due to the increased aircraft weights.Cu–15Ni–8Sn–0.8Nb alloy is well known...Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load‐carrying capability due to the increased aircraft weights.Cu–15Ni–8Sn–0.8Nb alloy is well known for possessing good mechanical and wear properties that satisfy such requirements.In this study,the microstructure,mechanical properties,and grease‐lubricated sliding wear behavior of Cu–15Ni–8Sn–0.8Nb alloy with 0.8 wt%Nb are investigated.The nanoscale NbNi3 and NbNi2Sn compounds can strengthen the alloy through the Orowan strengthening mechanism.A Stribeck‐like curve is plotted to illustrate the relationship among friction coefficient,normal load,and sliding velocity and to analyze the grease‐lubricated mechanism.The wear rate increases with normal load and decreases with sliding velocity,except at 2.58 m/s.A wear mechanism map has been developed to exhibit the dominant wear mechanisms under various friction conditions.When the normal load is 700 N and the sliding velocity is 2.58 m/s,a chemical reaction between the lubricating grease and friction pairs occurs,resulting in the failure of lubricating grease and an increase in wear.展开更多
The stability of NiO and oxidized nickel niobium surface alloy electrode under various molten carbonate fuel cell(MCFC) cathode conditions were investigated by determination of equilibrium solubility of nickel ions i...The stability of NiO and oxidized nickel niobium surface alloy electrode under various molten carbonate fuel cell(MCFC) cathode conditions were investigated by determination of equilibrium solubility of nickel ions in the carbonate melt of the two electrode materials.It is found that under MCFC cathode conditions the stability of NiO electrode is improved significantly by the deposition of niobium.As far as stability is concerned,oxidized nickel niobium alloy electrode can be considered as a candidate for cathode material of MCFC.展开更多
基金The authors are grateful to the State Key Laboratory of Nuclear Flue and Materials Foundation for support.
文摘The effect of heat treatment on martensitic transformation behavior has been investigated in Ti44Ni47Nb9 alloy. The relation between transformation temperatures and critical stress of stress induced martensitic transformation is interpreted in terms of thermodynamic theory. It is shown that the decrease in transformation temperature in specimens of slow cooling rate or low temperature aging after solution heat treatment results from the changes of Ni/Ti ratio in the matrix. The increase of critical stress of stress induced martensitic transformation is a consequence of the decrease of transformation temperatures.
基金The authors would like to express their gratitude for the financial support provided by the National Key Research and Development Program of China(Grant Nos.2017YFB0306105 and 2018YFE0306100).
文摘Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load‐carrying capability due to the increased aircraft weights.Cu–15Ni–8Sn–0.8Nb alloy is well known for possessing good mechanical and wear properties that satisfy such requirements.In this study,the microstructure,mechanical properties,and grease‐lubricated sliding wear behavior of Cu–15Ni–8Sn–0.8Nb alloy with 0.8 wt%Nb are investigated.The nanoscale NbNi3 and NbNi2Sn compounds can strengthen the alloy through the Orowan strengthening mechanism.A Stribeck‐like curve is plotted to illustrate the relationship among friction coefficient,normal load,and sliding velocity and to analyze the grease‐lubricated mechanism.The wear rate increases with normal load and decreases with sliding velocity,except at 2.58 m/s.A wear mechanism map has been developed to exhibit the dominant wear mechanisms under various friction conditions.When the normal load is 700 N and the sliding velocity is 2.58 m/s,a chemical reaction between the lubricating grease and friction pairs occurs,resulting in the failure of lubricating grease and an increase in wear.
文摘The stability of NiO and oxidized nickel niobium surface alloy electrode under various molten carbonate fuel cell(MCFC) cathode conditions were investigated by determination of equilibrium solubility of nickel ions in the carbonate melt of the two electrode materials.It is found that under MCFC cathode conditions the stability of NiO electrode is improved significantly by the deposition of niobium.As far as stability is concerned,oxidized nickel niobium alloy electrode can be considered as a candidate for cathode material of MCFC.
