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MATSE 259 Exam 3 Questions And Answers
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MATSE 259 Exam 3 Questions And Answers
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Solution 2024/2025Pepper
MATSE 259 Exam 3 Questions And Answers
how do we control material properties? ANS✔✔ by controlling the structure
why is the microstructure important? ANS✔✔ a changing microstructure changes properties
phase diagrams show how ______ and ______ affect the microstructure ANS✔✔ temperature, composition
what is a solid phase? ANS✔✔ chemically and structurally distinct materials
what is a liquid phase? ANS✔✔ Depends on miscibility
what is a gas phase? ANS✔✔ Always a single phase
what are phases? ANS✔✔ The physically and chemically distinct material regions that form
what is the lighter phase? ANS✔✔ beta
what is the darker phase? ANS✔✔ alpha
what is a phase diagram? ANS✔✔ Shows what phases to expect at a given temperature when an alloy of known
composition attains equilibrium
what issue are we looking to address in a phase diagram? ANS✔✔ when we combine two elements, what is the
resulting equilibrium state (in particular if we specify the temperature and composition)
what is a solution? ANS✔✔ single phase
, Solution 2024/2025
Pepper
what is a mixture? ANS✔✔ more than one phase
what is the solubility limit? ANS✔✔ maximum concentration for which only a single phase solution exists
if you change T and/or C, what could you be affecting? ANS✔✔ the number of phases
what is another name for a one component phase diagram? ANS✔✔ unary
what are the variables in a one component phase diagram? what is held constant? ANS✔✔ pressure and temperature,
composition
what is true about two phases along any line? ANS✔✔ they are at equilibrium
what is a special point in water? what phases exist? ANS✔✔ triple point, all three phases exist
what is an example of a one component phase diagram we look at? ANS✔✔ water
what are the variables in a two component (or binary) phase diagram? what is held constant? ANS✔✔ temperature and
composition, pressure
what are two component phase diagrams widely used for? ANS✔✔ understanding the microstructure of alloys
for two phase diagrams, when does the solidification of a liquid and the melting of a solid occur for a given composition?
ANS✔✔ at two different temperatures
what is the liquidus line? ANS✔✔ the line between the liquid phase and the solid+liquid phase
, Solution 2024/2025
Pepper
what is the solidus line? ANS✔✔ the line between the solid phase and the solid+liquid phase
what are the three rules used to understand phases, their compositions, and amounts? ANS✔✔ 1-2-1-2..., tie line rule,
lever arm rule
what is the 1-2-1-2... rule? how does it work? ANS✔✔ it specifies the number of phases, it only works horizontally, as
you go across the diagram, you start in one phase and then any time you pass over a line you will go to a 2 phase, and
then if you cross a line again it will be a 1 phase, etc
what is the tie line rule? where is it valid? ANS✔✔ gives the phases and compositions at a specific temperature, in a 2
phase region only!
what is the lever rule? ANS✔✔ gives the amounts of the two phases
why is there not time in phase diagrams? ANS✔✔ we are only worrying about stability, not kinetics
what does the liquidus line represent? ANS✔✔ temperature at which the substance is fully liquid
what does the solidus line represent? ANS✔✔ temperature at which the first bit of liquid is seen
when will a material melt? ANS✔✔ between a range of temperatures (between liquidus and solidus line)
what is the difference between a pure metal and an alloy? ANS✔✔ for pure metals, the melting will take place at a given
fixed temperature; if you melt an alloy, it will melt over a range of temperatures (there is no such thing as a melting
point of an alloy)
what is supercooling? ANS✔✔ During cooling of a liquid, solidification starts only after the temperature has been
lowered below the equilibrium freezing temperature
solidification of an alloy is significantly expedited when? ANS✔✔ if the system is agitated (added energy)
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