6.1. SOLID DISORDERED NANOSTRUCTURES
135
40
I
I
I
I
I
35
30
8
2 25
0
m
v,
n
h
2 20
U
15
10
5
' 15
25
35
45
55
65
75
GRAIN SIZE (nm)
Figure 6.2. Distribution of sizes of Fe-Cu nanoparticles made by hot compaction methods
described in the text. [Adapted from L. He and E. Ma, J. Mater. Res. 15, 904 (2000).]
number of particles having 40 nm sizes. Figure 6.3 shows a stress-strain curve for
this case. Its Young's modulus, which is the slope of the curve in the linear region,
is similar to that of conventional iron. The deviation from linearity in the stressstrain curve shows there is a ductile region before fracture where the material
displays elongation. The data show that fracture occurs at 2.8GPa which is about
5 times the fracture stress of iron having larger grain sizes, ranging from 50 to
150 pm. Significant modifications of the mechanical properties of disordered bulk
2.5
FRACTURE
1.5
0 . 5 1
,"
0
0 Q ~ l l l l " ' l ' ' l l " ' ' ' 1 1 1 1 1
0
0
0.01 0.02 0.03 0.04 0.05
STRAIN
Figure 6.3. Stress-strain curve for bulk compacted nanostructured F&u
material, showing
fracture at a stress of 2.8GPa. [Adapted from L. He and E. Ma, J. Mater. Res. 15, 904 (2000).]