Diffraction analysis of α-Fe precipitates in a polycrystalline Cu-Fe alloy

The microstructure and orientation of alpha-Fe precipitates after a small amount of deformation in a polycrystalline Cu-2.1 wt.% Fe alloy were investigated. Analysis of electron diffraction patterns and Moire fringes of alpha-Fe precipitates showed that the orientation relationship between alpha-Fe precipitates and Cu matrix was close to Pitsch relationship, while the results were contrary to the previous research. The simulated diffraction pattern along the [001](Cu), was established and the result was in good agreement with the experimental observation, which indicated that the mutually perpendicular streaks along < 220 >(Cu) directions came from the diffractions of precipitates in four variants. The interaction between the 1 (1) over bar0(Fe)/(1) over bar 10(Fe) diffraction of precipitates (under [110](Fe) zone axis) and the 200(Cu)/020(Cu), diffraction of matrix (under [001](Cu) zone axis) resulted in Moire fringes normal to the < 220 >(Cu), direction with spacing about 0.98 nm in the corresponding precipitates. After aging treatment, the twinned structure in the alpha:Fe precipitates disappeared and the orientation relationship between those alpha-Fe precipitates and Cu matrix finally satisfied Kurdjumov-Sachs relationship. It is concluded that Pitsch relationship and KS relationship can co-exist in polycrystalline Cu-2.1Fe alloy. (C) 2015 Elsevier Inc. All rights reserved.