Chemistry Reference
In-Depth Information
Austenite
Cementite
Miscibility gap
92
Fig. 10.16 Austenite and cementite in the composition band of iron and carbon (730
C)
A
lloys
Metal atoms “left + left in the PSE”
bonding undirected
I
ntermetallic phase
S
olid solution
Crystal structure of involved
kinds of particles remains
New crystal structure for
involved kinds of particles
S
ubstitutional solid
solution
I
nterstitial solid
solution
Particles fit into
the space
between others
Particles replace
others
I
ntermetallic compound
The homogeneity
range of the
phase is very small
S
uperlattice
Second kind of
particle is
also periodic
Fig. 10.17 Summary of pathways to the formation of alloys and intermetallic compounds
miscibility gap occurs for the example lead-tin: only the pure metals crystallize
from the melt, a heterogeneous mixture of lead crystals and tin crystals appears.
One last example shows that, apart from a miscibility gap, other compounds may be
formed: cementite, Fe
3
C (see Fig.
10.16
).
A final diagram will schematically summarize the multitude of possible
pathways to the formation of alloys and intermetallic compounds (see Fig.
10.17
).
