YAO Kefu TANG Naiyong CHEN Nanping Tsinghua University
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Beijing
,
China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A213—A218
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Ph.D.Student
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Dept.of Materials Sci.and Eng.
,
Tsinghua University
,
Beijing
,
China
金属学报(英文版)
The development of dislocation structures in the plastic zone ahead of a crack tip has been in- vestigated in a duplex stainless steel during in-situ deformation experiments in a scanning transmission electron microscope.It was found that the dislocation distribution was significantly different in the ferrite and in the austenite.In the ferrite grains,the dislocations emitted by the crack tip may cross-slip out of the original slip planes and form a broad plastic zone.However,in the austenite,the dislocation free zone is small and the dislocations emitted by the crack pile up in its slip plane.The selection of slip systems at the crack tip depends on the crack tip Schmid factors in both phases.But after large deformation,the selection of the second slip systems at the craek tip in austenite does not depend on the Schmid factors.
关键词:
crack tip
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null
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null
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null
陈言坤
,
杜仕国
,
鲁彦玲
,
汪明球
表面技术
doi:10.3969/j.issn.1001-3660.2010.05.023
在pH值不同的几种植酸转化液中对AZ91D镁合金进行表面转化处理,利用扫描电镜及自带能谱仪、Tafel曲线和阻抗谱等分析手段,结合NaCl水溶液点滴实验,研究了pH值对植酸转化膜表面成分及耐蚀性的影响.结果表明:在酸性条件下形成的植酸转化膜的耐蚀性较好;转化液的pH值会影响植酸螯合物的形成和转化膜的物质组成,进而影响转化膜的耐蚀性能;在酸性条件下,镁合金表面形成的植酸转化膜应属于电子导体膜,它阻碍了腐蚀介质与基体的接触,同时抑制腐蚀产物的扩散,对镁合金起到防护作用.
关键词:
镁合金
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植酸
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转化膜
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耐蚀性
Z. Zhang
,
W.H. Leng
,
J.Q. Zhang
金属学报(英文版)
The influence of pH value of the electrolyte solution on the zinc electroplating process was studied by means of cyclic voltammetry and chronoamperometry approaches. The results shown that, under this experimental conditions and at high overpotentials, the nucleation of zinc is instantaneous, and the nuclear densities N increase with the overpotentials. While at low potentials, no distinguished nucleation current can be observed. High pH promotes the deposition either by drifting the initial depositing potential positively, or by increasing the depositing current through the change of the total charge of the adsorption process Qads, i.e., theｖstructure of electrochemical double layer.
关键词:
zinc electroplating
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null
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null
