1.
Problem 4 (Phase Diagram ) : Magnesium-Lead phase diagram is shown in the figure below: a)
Identify the intermetallic solid compound. Provide the composition (in wt% Pb) and range of
temperatures in which the compound is formed. b) What is a eutectic reaction? Identify all the
eutectic points in the diagram and give the corresponding eutectic composition (CE) and
temperature (TE). c) Consider a mixture consisting of 10 wt% Pb at room temperature (T=20
degree C). To what temperature should this mixture be heated to dissolve all the Pb into Mg?
a)8090Pb
Solution
a)the intermetallic compound in the phase diagram is Mg 2 Pb
it exists at the composition of 19wt % Mg ,81 wt% Pb
it lies in the range between 0 0
C to a little over 549.5 0
C
b)
there are two eutectic reaction here one is
Comp.
Temp.
Type of Reaction
Reaction
(on cooling)
(i)
0wt%Pb
640
Comp. Temp. Type of Reaction Reaction

2.
(on cooling)
(i) 0wt%Pb 640