MAE4500_HW3_Sol - Manufacturing Methods MAE 4500 Fall...

Manufacturing Methods
MAE 4500 Fall Semester 2009
Solutions to Homework #3
1. A part given in figure 1 is to be made by casting. The following materials are considered: Al-
3%Si and Al-12.6%Si.
a) Copy the Al-Si equilibrium diagram and identify all phase fields.
b) Make two sketches showing the solidification of each of the above two alloys in cylindrical
molds (type of crystals, solidification shrinkage).
c)Make judgments on each material whether it will be:
i. Prone to alloying element segregation
ii. suffer from microporosity
iii. easy to feed
iv. of high fluidity
(Give your answers for each material in the above sequence; justify each answer in one
sentence.)
d)On the above basis, evaluate each material for its suitability for casting.
Solution :

a)
b) From figure 3-15 a and b of Schey
c)
i. Al-3%Si: prone to both micro and macro-segregation due to its wide solidification range
which causes dendritic solidification pattern. (Dendrites have a lower alloying element

concentration)
Al-12.6%Si: prone to normal segregation (macrosegregation) due to planar solidification