3.1 Mixing Elements
39
(a) subs alloy
(b) intersal alloy
(c) intermetallic (ordered alloy)
(d) separated phase
(with miscibility gap)
B,C,N
Fig. 3.5 Schematic illustrations of atomic arrangements in different types of binary mixtures
function of the alloy being closer to that of a low-melting-point metal. By taking this
into account, a schematic representation of the effect of the chemical composition
on the work function in binary substitutional alloys and the corresponding phase
diagram are shown in Fig. 3.6.
Some examples of the work function in alloys are demonstrated in Fig. 3.7a–
e, together with their phase diagrams. For Nb–Mo, both metals are early transition
metals (the number of d-electrons is less than 5) and have high melting temperatures;
a nearly linear relationship between the composition and the work function has been
reported, as shown in Fig. 3.7a [4]. For Ag–Au, where both metals are noble but have
different atomic sizes, the work function smoothly changes with the composition
Fig. 3.6 Schematic
representation of influence of
chemical composition on
work function in binary
substitutional alloys and
corresponding phase diagram
composiion
composiion
temperature
work funccon