Neutron Scattering Studies of the Effects of Uniaxial Stress and Ageing on the β 1–Cu–Al–Zn Alloy

In the present paper, we give the results of neutron scattering studies on the β 1 -phase of Cu–17.0Al–14.3Zn alloy. Our interests are mainly concerned with both phonon dispersion relations and elastic scattering anomalies of single crystal specimens: the one is under the [001] compressive stress and the other after ageing. Behaviours of the [110]TA 1 phonon branch indicate that the [001] stress enhances the lattice instability relating to the β 1 -to-martensite transition. The 2/3 q 0 -peak is not due to any martensites. The ageing at 373 K for 7 days has no influence on the [110]TA 1 , [111]LA and [112]TA phonon branches and also on the 2/3 q 0 - and ω-like peaks. The result means that the ω-like peak is not due to the ω-phase formation. Both the 2/3 q 0 - and ω-like peaks would be caused from a certain kind of regular arrangements of vacancies in the L2 1 -type β 1 -phase.