Phase formation in rapidly quenched Cu-based alloys

Abstract

In the present investigation, we report the formation of γ-brass type phase in the rapidly quenched Cu50Ga30Mg5Ti15 and Cu50Al30Mg5Ti15 alloys. Rapid solidification of Cu50Ga30Mg5Ti15 alloy shows the formation of simple cubic γ-brass type phase (a = 0.863 nm), which on annealing at 1,023 K for 60 h transforms to disordered type γ-brass phase (a = 0.879 nm). It has been observed that intensity modulation of electron diffraction spots corresponding to simple cubic γ-brass phase is similar to the intensity modulation observed in the mirror orientation of icosahedral quasicrystalline phase. Contrary to the crystalline phase formation in Cu–Ga–Mg–Ti alloy, rapid solidification of Cu50Al30Mg5Ti15 shows the formation of amorphous and nanocrystalline bcc γ-brass type phase (a = 0.870 nm), which on annealing transforms to ordered γ-brass type phase (a = 0.872 nm). The structural and microstructural characterization was done through X-ray diffraction and transmission electron microscopy.