采用X射线衍射方法,显示出镁-5Wt％锌合金在165℃时效初期有两种过渡相β′_1和β′_2共存。对细杆状过渡相,β′_2的一维衍射现象进行了详细分析。这种过渡相具有六角点阵结构,其[0001]轴是杆的长轴,它的点阵常数及与母相间的取向关系经测定为:a_(β′_2)=13.2,c(β′_2)=5.25,[0001]_(β′_2)∥[0001]_M,<1010 >_(β′_2)∥<1010 >_M。文中还讨论了由β′_2沉淀于基体中产生点阵畸变的问题。 X-ray diffraction shows that there are two kinds of transitional phases β’_1 and β’_2 coexist in the early stage of aging at 165 ℃ for magnesium-5Wt% zinc alloy. One-dimensional diffraction phenomenon of β’_2 was analyzed in detail for the thin rod-like transition phase. The transition phase has a hexagonal lattice structure, the axis of which is the long axis of the rod, and its lattice constant and the orientation relationship with the mother phase are determined as follows: a_ (β’_2) = 13.2, c (β ’ _2) = 5.25, [0001] _ (β’_2) // [0001] _M, <1010> _ (β’_2) // <1010> _M. The paper also discusses the problem of lattice distortion caused by the deposition of β’_2 in the matrix.