粒界破断したピーク時効状態のAl–Zn–Mg合金における結晶粒界の特徴

概要

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In this paper, the phenomenon of intergranular fracture in a peak-aged Al–6.7%Zn–2.8%Mg–0.4%Cu alloy has been investigated by an electron backscattered diffraction (EBSD) technique and the effect of crystallographic orientation on the crack propagation was clarified. Individual grain boundaries were divided into four groups based on their difference in Schmidt factor (S.F.) and stress transfer factor (Nij). The difference in S.F. higher than 0.05 corresponds with the groups A and B and lower that 0.05 is characteristic for the groups C and D. Nij factor higher than 0.5 is specific for the groups A and C and the groups B and D having this factor lower than 0.5. It has been found that grainboundary fracture occurs at the boundaries belonging to the group D in 46% of all cases, in 24% corresponding with the group B and in 23% with the group C. Preferential deformation in the vicinity of grainboundaries belonging to the group B has been also verified by an atomic force microscopy (AFM) technique as the same as a case in the peak-aged Al–Mg–Si alloy.
一般社団法人軽金属学会の論文