L-F. Li
,
Z. Zhang
,
and Y Y Li(Cryogenic Laboratory Chinese Academy of Sciences
,
Beijing 100080
,
China)(Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
The microstructure of a fine-grained 16.5mol% CeO2 stabilized tetragonal zirconia polycrystal (Ce-TZP has been investigated by TEM and it is shown that the mi-crostructures of samples fractured at 298, 77 and 4.2 K change significantly. At 298K there is no stress-induced martensite but a few anti-phase boundaries (APBs) in tetragonal (t) parent phase. With a decrease in temperature, monoclinic (m) product or mariensite within retained t-phase appears. The morphologies are characterized as lenticular and block-like at 77 K and as lenticular and butterfly-like at 4.2 K. The relationship between microstructure and mechanical properties is also discassed in this paper.
关键词:
microstructure
,
null
,
null
Z. Zhang
金属学报(英文版)
Wavelet transforms (WT) are proposed as an alternative tool to overcome the limita-tions of Fourier transforms (FFT) in the analysis of electrochemical noise (EN) data.The most relevant feature of this method of analysis is its capability of decomposingelectrochemical noise records into different sets of wavelet coefficients, which containinformation about the time scale characteristic of the associated corrosion event. Inthis context, the potential noise fluctuations during the free corrosion of pure alu-minum in sodium chloride solution was recorded and analyzed with wavelet transformtechnique. The typical results showed that the EN signal is composed of distinct typeof events, which can be classified according to their scales, i.e. their time constants.Meanwhile, the energy distribution plot (EDP) can be used as "fingerprints" of ENsignals and can be very useful for analyzing EN data in the future.
关键词:
electrochemical noise
,
null
,
null
,
null
,
null
Z. Zhang
,
C. Cai
,
F.H. Cao
,
Z.N. Gao
,
J.Q. Zhang
,
C.N. Cao
金属学报(英文版)
The corrosion behavior of pure aluminum in neutral 3.0% (mass fraction) sodium chloride (NaCl) solution has been studied using electrochemical impedance spectroscopy (EIS) measurement in conjunction with the scanning electron microscopy (SEM) technique. EIS information on the evolution of pitting corrosion over a period of 15 days has been obtained and analyzed with equivalent circuit technique. The results shown that, during the ensemble constant immersion time, two time constants involved, the high frequency one originated from the protective layer on the corroding surface while the low frequency one from the diffusion process or the corrosion reaction and so on. And there existed a period for oxide film to growth and thickening prior to the commencement of the attacking of chloride ions to the substrate. Meanwhile, good relationship between EIS and the material corrosion type / severity has been obtained, which has been interpreted according to the characteristics of corrosion process such as auto acceleration of pitting corrosion and the protection of local anodic reaction to the area around them.
关键词:
pure aluminum
,
null
,
null
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
,
null
,
null
王晓旭
,
陈利
材料工程
doi:10.3969/j.issn.1001-4381.2011.11.001
通过单根Z-pin从复合材料层合板中拔出的试验方法,测试了Z-pin的拔出强度,计算了Z-pin的临界埋入深度,并引入抗拉强度利用率概念来表征Z-pin的抗拉强度在拔出过程中的利用程度.结果表明,直径0.50mm和0.28mm的Z-pin临界埋入深度分别约为5.1mm和3.1mm.当Z-pin的埋入深度小于临界埋入深度时,Z-pin从层板中拔出；Z-pin拔出强度与埋入深度成正比,与Z-pin的直径成反比；当Z-pin的埋入深度大于临界埋入深度时,Z-pin发生断裂,Z-pin的抗拉强度利用率达到100％.最后提出了提高抗拉强度利用率的建议.
关键词:
Z-pin
,
拔出强度
,
复合材料
,
拔出试验
,
抗拉强度
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
王晓旭
,
陈利
航空材料学报
doi:10.3969/j.issn.1005-5053.2011.4.017
通过三种复合材料Z-pin的轴向压缩试验,观察了各Z-pin的压缩行为,分析了三种复合材料Z-pin在不同长度时的极限应力及其失效形式.结果表明,直径为0.50mm的碳纤维Z-pin的压缩性能最好,其各长度Z-pin所能承担的极限应力都较大.直径0.28mm的碳纤维Z-pin易发生失稳现象,芳纶纤维Z-pin在压缩力的作用下,接触端容易受到破坏.两种碳纤维Z-pin临界应力的理论值与试验值吻合较好,但芳纶纤维Z-pin的临界应力的试验值比理论值偏低.
关键词:
Z-pin
,
复合材料
,
压缩试验
,
临界应力
Li XING
,
Jie ZHAO
,
Fuzhong SHEN
,
Wei FENG
材料科学技术（英文）
A Z-parameter method is used to evaluate the damage process of HK40 austenitic steel. By using Z-parameter based on the Larson-Miller method, the nonlinear master curve of the log stress vs Larson-Miller parameter P can be expressed as: P=27.74-3.4lgσ-0.032σ, and a family of curves parallel to the master curve can be written as: P=(27.74-Z)-3.4lgσ-0.032σ, where Z represents the magnitude of the deviation from the master curve. According to the creep rupture data both from different segments of a serviced tube and from the same segment locations with different service time, the value of parameter Z has close relationship with the deterioration of creep rupture properties. The damage state of the samples is evaluated by monitoring the changes in natural frequency f and Young0s modulus E, and the relationships between Z and the damage parameters are discussed.
关键词:
Damage evaluation
,
蠕变断裂
,
奥氏体钢
,
Z参数
