QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
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Beijing
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China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
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Journal of Materials Processing Technology
This paper has studied systematically the preparation technology and its effects on the structure and amorphous forming region (AFR), and theoretical description of the AFR for electroless Ni-P alloys. It has been found that the deposition rates increase and approach a maximum value and then decrease with the increase in the concentration of nickel chloride, sodium hypophosphite and pH value, respectively. However, the deposition rates decrease with the increase in sodium citrate. The AFR is P > 9-10 at.% in the range of concentration of nickel chloride studied. In the ran-e of concentration of sodium hypophosphite studied, there was no crystalline structure observed. The AFR calculated theoretically using the Miedema model was in good agreement with the experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.
关键词:
electroless Ni-P alloys;preparation technology;structure;amorphous;forming region;Miedema model;formation enthalpies;nickel deposition;mechanism
