LIU Jian QIU Baoqin LIU Muyi XIAO Yaofu University of Science and Technology Beijing
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Beijing
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China associate professor
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Department of Materials
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University of Science and Technology Beijing
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Beijing 100083
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China
金属学报(英文版)
The phase constitution and variation of Nd_(14)Fe_(73)Co_6B_7 alloy after hydriding and subsequent dehydriding treatment at 770℃ have been investigated respectively by means of X-ray diffraction,SEM,TEM and magnetic measurement techniques.The original coarse,as cast grain structure,is dissolved into α-Fe,Nd hydride and Fe_2B mixture with average dimension of 0.1 μm,during hydriding process,and subsequently the triphase mixture recombined into finely unique Nd_2Fe_(14)B phase with dimension of 0.3 μm by desorbing the hydrogen.It was found that the Nd-rich phase distributed at the boundary of as-cast grain structure diffused into matrix Nd_2Fe_(14)B grain during hydriding.It remains during dehydriding and distribute homogeneously around some colonies composed of fine grains of Nd_2Fe_(14)B.
关键词:
Nd_(14)Fe_(73)Co_6B_7
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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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