CASTING AND PHASE DIAGRAMS

VIDEO BASED MODULE

DEVELOPED THROUGH THE NATIONAL SCIENCE FOUNDATION'S GATEWAY ENGINEERING EDUCATION COALITION

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This video based module documents an experiment which was developed at the University of South Carolina by Dr. Jed S. Lyons to motivate students to study equilibrium phase diagrams. The approach taken was to combine industrial-style foundry operations with quantitative laboratory measurements. This demonstrates the relevence (and limitations) of material generally presented by lecture. A brief summary of the module is given below.


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In the experiment, a master alloy is made from pure aluminum and pure copper. Students combine enough master alloy with more aluminum to make a casting alloy with a composition of their choosing.
Each casting alloy is inductively melted and cast into an oil-bonded sand mold. Thermocouples embedded in the mold cavities are used to record temperatures during the solidification processes.
The mold is then completed by attaching the upper portion which has a sprew for mold filling and risers that act as reservoirs to account for solidification shrinkage.
The casting alloy is then poured into the mold.
The thermocouples are connected to a computer which provides a plot of temperature vs. time. This cooling curve is used to measure the inflection temperatures during solidification.
The inflection temperatures are related to the liquidus and solidus lines of the equilibrium phase diagram for the aluminum-copper system. These temperatures are lower than the equilibrium values because undercooling is necessary to drive the solidification process.
The casting is removed from the mold after cooling. Metallographic samples wll be examined to reveal how alloy composition affects the resulting microstructure.



Download a summary of the casting video in AVI format.

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