The rapidly solidified Mg-4.8Zn-0.6Yribbons were prepared by melt-spun rapidly solidification with a single roller.The microstructures

phase constituent

micro-segregation and solidification characteristics of the alloy were investigated by SEM

TEM

XRD

EDX and DTA.The results show that the microstructure of rapidly solidified Mg-4.8Zn-0.6Yribbons consists ofα-Mg supersaturation solid solution

quasicrystals I（Mg3YZn6）and X（Mg12YZn）

and the fine equiaxed grain size in free surface reaches 1

3

μm.It indicates that the cooling rate of rapid solidification about 4.60×106

1

.04×107 K·s-1 meets the cooling conditions of quasicrystalline phase precipitation.Magnesium

zinc and yttrium are distributed uniformly along thickness cross section of the rapidly solidified ribbon

however

there exists a small amount of microsegregation in the thickness of ribbons and within the grains as well.Microsegregation is attributed to the difference from the copper substrate to the free surface of ribbons and the solidification velocity rate of solute transport and lattice structure

and for the segregation trend of three elements

Zn is the largest

and then Y

Mg.