The 15%cin volumetric fraction

chopped carbon fibers reinforced magnesium composites(C

sf

/AZ91D)were prepared by vacuum assisted pressure infiltration method

and the isothermal constant strain rate compression experiment of C

sf

/AZ91 Dcomposites was carried out at the deformation temperatures from 400 ℃to 460 ℃ and strain rates from 0.001s

-1

to 1s

-1

and the true strain of 0.7to understand the behavior of flow stress and dynamic recrystallization.The results indicate that the softening mechanism of the dynamic recrystallization is a feature of true stress-true strain curves of C

sf

/AZ91 D composites

and the critical strain is decreased with increasing in temperature or decreasing in strain rate.The functional relationship with parameter Zcan be exhibited asε

c

=1.6×10

-3

Z

0.037 2

and there enists a linear relationship between critical strain and peak strain

ε

c

=0.385 2ε

p

.The critical strain of the composites is much less than that of magnesium alloy AZ91 D

and the chopped carbon fibers promote the occurrence of dynamic recrystallization of matrix magnesium alloy and refine the recrystallization grains.