17. Phase Diagrams II

Question 1

Define eutectic system

Answer 1

a mixture of chemical compounds or elements that have a single chemical composition that solidifies at a lower temperature than any of its constituents

Question 2

True or False: In a binary eutectic system, the eutectic point describes a single composition at which liquid transforms to a solid phase (or vice versa) over a narrow temperature range.

Answer 2

False

Question 3

True or False: The liquidus line delineates the boundary between a two- phase solid-liquid region and a solid region.

Answer 3

False

Question 4

True or False: The lever rule can be used to determine the distribution of a component within cored structures resulting from equilibrium cooling.

Answer 4

False

Question 5

When does the lamellar microstructure form?

Answer 5

When at a liquid at the eutectic composition is cooled beyond the eutectic point

Question 6

Why does the lamellar microstructure form?

Answer 6

Because the solidification happens so fast that the diffusion can only occur to a very small extent

Question 7

Concentrations lower than the eutectic is _____

Answer 7

hypoeutectic

Question 8

Concentrations higher than the eutectic is _____

Answer 8

hypereutectic