7. Phase Flashcards
MICROSTRUCTURAL CONTROL
Yay!
How do you transform something?
Movement of atoms!
What determines the phase an alloy takes?
1) Alloy composition
2) Temp
3) Pressure (but not for solids)
What do phase diagrams give?
Phases of lowest energy for equilibrium for any combo of temp and composition
What is liquidus? Solidus?
Liquidus is the temp above which 100% of the alloy is liquid
Solidus is the temp below which 100% of the alloy is solid.
What’s a tie line?
A line drawn on an isotherm. Where it intersects the solidus line describes the composition of the solid, and on the liquidus, the composition of the liquid.
What are the three things you can get from a phase diagram?
1) The phases present for a given temp + composition
2) Compositions present
3) Weight fraction of phases
What is the lever rule?
A rule for determining how much of a composition is in solid vs liquid. Measure distance on tie line between solidus and liquidus lines - a / (a+b) gives you the fraction
Using the lever rule, what happens when you keep temp constant and change the composition of a material?
The comp of the solid and the comp of the liquid don’t change, but the % weight of each changes
On a phase diagram, what do the broken lines mean?
Broken lines are probable boundaries.
Liquid/solid
Solid/solid?
Dendritic
Equiaxed
