extra detailed notes on phase diagrams Flashcards
spcfc tm of eutectic
lower than of any other compositions
tell more about non equiliibrium cooling of alloys
if we rapid cool it we wont have sufficiient time for solid state diffusion
however sometimes we can later perform heating homogenization treatment which is done at t below tm which will make the microstructure more uniform
at eutectic line
alpha beta and liquid meet in equilibrium
peritectic
s plus liquid make solid
eutectoid
s make s plus s
what is created if we do fast cooling
core grains
what issues can come up due to non equilibrium cooling
- phase changes may occur at different temperatures or may vary
microstructure (fine & coarse pearlite) - may get phases at room temperature which are not on the phase
diagram, i.e. non equilibrium phases.
alloiying elements
When other elements (in addition to carbon) are added to steels they
can affect the Fe-Fe3C diagram.
* Some move eutectoid temperature up
* Some move eutectoid temperature down
* Some move eutectoid to higher carbon concentrations
* Some move eutectoid to lower carbon concentrations
last page about hypo and hyper eutectic refer back to it
iron phase diagram cooling
slow cooling not true equilbrm
Fe3C
cementite or iron carbide
what the irone phase diagram contains
austenite y
ferrite alpha and sigma
cementite
liquid
austenite
carbon intersisitial solid sln in fcc iron
cementite
intermetallic compound
ferrite alpha
bcc intsttl carbn solid sln in iron
