In this paper, we study the photoluminescence (PL) lifetimes in AlGaN alloys with incommensurate chemical ordering. AlGaN films were grown by RF plasma-assisted MBE under different kinetic conditions. The compositions in all films were maintained at a constant value of 72 % AlN mole fraction by using the same Al flux, while the kinetics of growth were controlled by varying the Ga flux and thus the III/V flux ratio during deposition of the various films, with some of the films grown under Ga-rich conditions and others under N-rich conditions. The structure of these films was previously investigated by XRD using synchrotron radiation and by SED-TEM.