Chapter 9 - Phase Diagrams

Question 1

binary eutectic diagram

Answer 1

three single-phase regions are found, one or more phases may be in equilibrium within a phase field, single-phase regions are always separated form each other by a two-phase region that consists of the two single-phases that it separates

Question 2

solvus line

Answer 2

the solid solubility limit line between the alpha and alpha+beta or beta and alpha+beta phase regions

Question 3

solidus line

Answer 3

the boundary between the alpha and alpha+L or alpha beta and beta+L fields

Question 4

liquidus line

Answer 4

line between liquid state and other phases

Question 5

invariant point

Answer 5

the point at which the two liquidus lines meet

Question 6

eutectic reaction

Answer 6

when upon cooling, the liquid phase is transformed into two solid phases

Question 7

eutectic isotherm

Answer 7

horizontal solidus line at Te

Question 8

ferrite

Answer 8

the stable form of pure iron at room temperature, alpha-iron, BCC crystal structure, also happens after 1394 degrees C

Question 9

austenite

Answer 9

gama-iron, FCC, iron after 912 degrees C, non-magnetic

Question 10

cementite

Answer 10

iron carbide (Fe3C), metastable (will remain as a compound indefinitely at room temperature)

Question 11

wt% C in Irons

Answer 11

pure iron: wt% < 0.008
steel: 0.008 < wt% < 2.14
cast iron: 2.14 < wt% < 6.70 (normally < 4.5)

Question 12

pearlite

Answer 12

alternating ferrite and cementite layers

Question 13

Hypereutuectoid alloy

Answer 13

Between .76 and 2.14 wt% C cooled from them in the gamma phase