Small-angle neutron scattering of single crystals of aged aluminium-13 at.% magnesium alloy

X-ray, neutron and electron diffraction experiments have revealed the existence of internally ordered Guinier-Preston zones in Al-(8 to 15 at.%)Mg alloys; diffuse satellites oriented along (100) directions are observed near Bragg peaks and give rise to modulated contrasts by TEM. A small-angle neutron scattering experiment has been carried out on single crystals and a model is proposed for the interpretation of the observed pattern. The existence of concentration modulations is related to alignments of spherical GP zones along (100) directions.