The defects and the k—state of Ni

75

Cr

15

Fe

10

alloy have been investigated using positron annihilation technique. In order to estimate the dislocation density and the vacancy concentration of the plastic deformed samples

the lineshape parameters have been measured as a function of the thickness reduction. When the thickness reduction varied from 4% to 25% the variable ranges of the dislocation density and the vacancy concentration were from 5.2×10

9

cm

-2

to 3.4×10

11

cm

-2

and from 2.0×10

-6

to 3.0×10

-4

respectively.

The dependence of the positron lifetime and the lineshape parameter on the annealing temperature (250℃~800℃) were measured. The k—state of this alloy could be formed around 350℃.