SCT2013 METALLURGICAL TECHNOLOGY
TUTORIAL: PHASE DIAGRAM
1.
a) Construct a complete temperature/composition diagram for the binary system of Cu-Ni based on
the data shown in Table 1.
Table 1
Temperature
2.
(oC)
Melt composition
Composition of solid first formed
(atomic %Ni)
on cooling (atomic %Ni)
1100
3
10
1180
20
37
1260
40
57
1340
60
73
1410
80
87
1455
100
100
Based on the phase diagram shown in Figure 1, at each point marked as T1-T5, determine the
following for the alloy of composition Co (41 wt% B):
a) phases
b) composition of the phases
c) weight fractions of the phases
Figure 1
3.
Phase diagram of Cu-Ag is shown in Figure 2.
Figure 2
a)
A 90 wt% Ag alloy is heated to a temperature within the β + liquid phase region. If the composition
of the liquid phase is 85 wt% Ag, determine:
i.
the temperature of the alloy
ii.
the composition of the β phase
iii.
the mass fractions of both phases
b) For equilibrium solidification of a Cu-Ag alloy containing 40 wt% Ag, state the followings:
i.
the temperature at which solidification begins.
ii.
the temperature at which solidification is complete.
4.
A 1.5 kg sample of 90 wt% Pb-10 wt% Sn alloy is heated to a 250 oC where at this temperature it is
an entirely -phase solid solution. The alloy is to be melted to the extent that 50% of the specimen is
liquid but the remainder being the  phase. This may be accomplished either by heating the alloy or
changing its composition while holding the temperature constant. The phase diagram of Pb-Sn system
is shown in Figure 3.
Figure 3
a) To what temperature must the specimen be heated?
b) How much tin must be added to the 1.5 kg specimen at 250 oC to achieve this state?