Precipitation behavior of an Fe-1.03 wt.% Cu alloy

The precipitation behavior of a high-purity Fe-1.03 wt. % Cu alloy during ageing at 650 degreesC has been investigated by transmission electron microscopy. The microstructure and the corresponding diffraction patterns of the {100}*, {110}* and {111}* reciprocal planes were analysed. A metastable phase with a B2-like structure was observed, which is quite different from the equilibrium copper phase shown in the Fe-Cu phase diagram. The formation mechanism of the B2-like structure is deduced based on the energetic point of view.