We consider transient behaviour in antiphase coarsening in simple bina
ry alloys, and corrections to late-stage asymptotic scaling with an ex
ponent of one half. (The problem might be of some importance to the me
tallurgical properties of composite microstructures.) Segments of anti
phase boundaries in three dimensions, with initially small total curva
ture, evolve rapidly, resulting in an effective growth exponent n(eff)
(t) = 1/2[1 + xi'/R(t)BAR] where xi' is a microscopic length and R(t)B
AR is the characteristic antiphase-domain size at time t.