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1.
1IntroductionNickel-based alloys containing 20 -30 wt % Mo isknown to be essential for corrosion resistance in re-ducing media[1],especially for resistance to HCl at alltemperatures and concentrations[2]. However , uponexposure to elevated temperatures in the range of600 -800 ℃,these alloys suffer an al most completeloss of roomtemperature ductility as a result of long-range ordering (LRO) to Ni4Mo .It is considered thatthe loss of ductility mainly results from the environ-mental embrittle…  相似文献   

2.
The mechanism involving the effect of disorder/order transformation on the environmental embrittlement in gaseous H2 is summarized. It is shown that there is no hydrogen embrittlement in disordered state of Kurnakov type intermetallics in gaseous H2. However, the H2-induced environmental embrittlement for the ordered alloy having identical chemical composition becomes severer as the degree of the order increases. The results of testing on the ion gage turned on and off during tensile testing show that the more sensitive to H2-induced hydrogen embrittlement for ordered alloy than disordered one is attributed to the fact that atomic ordering may accelerate the kinetics of the catalytic reaction to produce more atomic hydrogen. The results on simultaneous hydrogen charging show that disordered alloys embrittled as hydrogen atoms are forced into the material implying that the embrittlement of ordered alloy in gaseous H2 is also due to the acceleration of the kinetics of catalytic reaction. The above suggestion was further verified by the adsorption tests of Ni3Fe intermetallics powder. It is shown that the amount of chemically adsorbed hydrogen in ordered state is significantly larger than that adsorbed by the disordered alloy, indicating that the more sensitive to H2-induced embrittlement in the ordered state of alloy is essentially due to the accelerated catalytic reaction.  相似文献   

3.
硼对金属间化合物Ni_3Fe氢气诱发环境氢脆的影响(英文)   总被引：1，自引：0，他引：1  
In this paper the tensile properties of both ordered and disordered Ni-24Fe and Ni-24Fe-0.03%B(wt%)alloys in gaseous hydrogen was investigated.The result shows that the ductility of the disordered Ni_3Fe is significantly larger than that of ordered material in gaseous hydrogen.However,the ductility of ordered Ni3Fe doped with 0.03%B is nearly the same as that of disordered one indicating the obvious suppressing effect of boron on the H_2-induced embrittlement.Based on the segregation behavior of boron in Ni_3Al,it is proposed that the suppressing effect of boron in Ni_3Fe on the H_2-induced embrittlement is attributed to the segregation of boron on grain boundaries,thereby reducing the hydrogen diffusivity along the grain boundaries.  相似文献   

4.
1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｏｗｉｎｇｔｏｉｔｓｈｉｇｈｈｙｄｒｏｇｅｎ ｓｔｏｒａｇｅａｂｉｌｉｔｙ ,ｌｏｗｃｏｓｔａｎｄａｂｏｕｎｄｉｎｎａｔｕｒａｌｒｅｓｏｕｒｃｅｓ ,Ｍｇ ｂａｓｅｄａｌｌｏｙｂｅ ｃｏｍｅｓａｃｏｍｐｅｔｉｔｉｖｅｈｙｄｒｏｇｅｎ ｓｔｏｒａｇｅｍｅｄｉｕｍｗｈｉｃｈｃａｎｂｅｕｓｅｄｉｎＮｉ ＭＨｂａｔｔｅｒｙａｎｄｆｕｅｌｃｅｌｌ.Ｔｈｅｅｌｅｃ ｔｒｏｃｈｅｍｉｃａｌｍｅｔｈｏｄｈａｓｂｅｅｎｕｓｅｄｉｎｔｈｅｓｔｕｄｙｏｆｈｙ ｄｒｏｇｅｎａｔｉｏｎ/ｄｅｈｙｄｒｏｇｅ…  相似文献   

5.
In this paper the tensile properties of both ordered and disordered Ni-24Fe and Ni-24Fe-0.03%B （wt%） alloys in gaseous hydrogen was investigated. The result shows that the ductility of the disordered Ni3Fe is significantly larger than that of ordered material in gaseous hydrogen. However, the ductility of ordered Ni3Fe doped with 0.03%B is nearly the same as that of disordered one indicating the obvious suppressing effect of boron on the H2-induced embrittlement. Based on the segregation behavior of boron in Ni3A1, it is proposed that the suppressing effect of boron in Ni3Fe on the H2-induced embrittlement is attributed to the segregation of boron on grain boundaries, thereby reducing the hydrogen diffusivity along the grain boundaries.  相似文献   

6.
The process of gaseous hydrogen charging into a Ti3Al-based alloy in the temperature range of 500–650°C is investigated. The results showe that the relationship between the average hydrogen concentration at constant temperature and charging time reveals a parabolic rate law. Applying the theory of lattice diffusion to analyze the hydrogen diffusion in the alloy, we find that the apparent activation energy of hydrogen diffusion is 90.40 kJ/mol, and the equilibrium hydrogen content in the alloy depends on the temperature of the gaseous hydrogen charging process. Project supported by the Natural Science Foundation of Shanghai (93QE14002)  相似文献   

7.
Mg-25 wt% Mg2Ni composite was prepared by sintered method,hydrided at 613 K and then ball-milled with 1.5 wt% PdCl2 additive for 51 h. The effects of PdCl2 on the hydriding and dehydriding behavior of Mg-25 wt% Mg2Ni composite were investigated. The absorption and desorption rate of the composite with PdCl2 is fast and the hydrogen storage capacity is more than that of the composite without PdCl2. The maximum hydrogen storage capacity reached 3.48 wt% at 373 K,and 5.05 wt% H at 453 K,respectively. The improvement of sorption and desorption kinetics is attributed to the catalytic effect of PdCl2,and the grain refining and lattice strain introduced by ball milling.  相似文献   

8.
INTRODUCTION Mg-based alloys are considered as potentialcandidates for hydrogen storage materials because oftheir large hydrogen capacity (Reilly and Wiswall,1968; Pedersen and Larsen, 1993). However, asMg-based alloys desorb hydrogen at temperatureshigher than 600 K, they are not applicable to practicaluse. Many researches have studied to improve hy-driding/dehydriding kinetics and to lower the workingtemperature (Wang et al., 2002; Tsushio et al., 1998;Spassov and K?ster, 1998; Orim…  相似文献   

9.
Mg2Ni0.8Cr0.2-x wt.% CoO/Al2O3 (x=0.5, 1, 2 and 3) composites were prepared by mechanically milling sintered Mg2Ni0.8Cr0.2 alloy and CoO/Al2O3 compound for 45 h. The addition of CoO/Al2O3 compound resulted in the good kinetics properties of hydriding/dehydriding reaction of the composites. The composite with 1.0 wt.% CoO/Al2O3 catalyst could reach the maximum hydrogen absorption capacity (2.9 wt.%) within 5 min at 393 K under H2 pressure of 4 MPa, and can desorb rapidly at 493 K. The decomposition and synthesis of hydrogen molecule on Mg2Ni0.8Cr0.2 alloy surface was promoted by addition of CoO/Al2O3 catalyst. In addition, the formation of metallic Ni particles, strain and defects during the ball milling process also resulted in the improved hydrogenation performance of Mg2Ni-based alloys.  相似文献   

10.
采用简单、高效的方法,成功制备了应用于碱性介质电催化制氢的Ni-MoxNy/NF电极,对其进行XRD、SEM、TEM和XPS表征,并系统研究了该电极的电催化析氢性能。结果表明:产物的相组成物为单质Ni、Mo2N及Mo5N6。控制工艺条件,可制备出性能最佳的相结构为Ni-Mo2N,Mo5N6的含量增加不能提高产物的性能;性能最佳试样的显微形貌呈现纳米棒状,Ni(111)与Mo2N(200)构成的异质结构界面赋予材料优异的电催化析氢性能,在碱性电解质中,10mA/cm2下析氢过电位达 21mV,接近20%Pt/C电极(18mV),Tafel斜率为39.9mV/dec。电极的优异性能既来源于高电化学活性面积,也来源于其高本征活性,跻身当前性能最佳的非贵金属催化材料,为非贵金属碱性析氢电催化材料的、研发提供了新思路。  相似文献   

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