Chapter 3 Flashcards
What is the equation for enthalpy?
H = U + PV
What is the equation for the Gibb’s free energy at constant pressure?
G = H - TS
What is the specific heat?
quantity of heat required to rais the temperature by one degree kelvin at constant pressure.
What are intensive properties?
Independent of size (T and P)
What are extensive properties?
Size/quantity dependent (V, U, H, S, and G)
What is the Latent Heat?
heat released or absrobed by a chemical substance or a thermodynamic system during a process that occurs without a change in temperature
What does “undercooling the melt” means?
It means cooling faster than the material is able to crystallize
During crystallization is heat being released or absorbed
released
What type of grains are created during slow cooing process?
round
What type of grains are created during slow cooing process?
Dendritic grains
What shape allows for the minimum surface energy?
Sphere
What are wulff crystals?
Crystals that grow assymetrically due to areas with higher surface energy
Which side grows faster in a crystal: ones with lower or higher surface energy? What shape?
Sides with higher surface energy like flat surfaces.
What does the entropy of mixing consist of?
i) configurational and ii) vibrational or thermal entropy
Entropy of mixing consists of configurational and vitrational (thermal) entropy? Which is larger?
Configurational. Vibrational or thermal are often negletegted to first order.
How can activities be measured in the context of chemical potentials?
1) partial pressure of vapor in equilibrium with a solid, 2) electrolitic transfer in a galvanic cell (EMF), 3) Equilibrium with ideal solution (reference) and concentration measurment
What is a phase?
uniform state of matter within a system that is physically distinguishable in terms of composition and structure from other states and theoretically separable
What is the phase rule?
relates the physical state of a mixture to the # of constituents in the system and to its conditions.
What are the three gamma stabilizers?
Ni, Co, Mn
What are gamma stabilizers?
Components that enlarge the gamma phase therefore increasing solubility.
What are alpha stabilizers?
gamma phase reduced and alpha enlarged
Name all alpha stabilizers
Cr, Al, Ti, Si, Mo, W, V
What is the dominant cause of RPV embrittlement?
Formation of high number density of nanometer copper rich precipitates
How does copper end up in the RPV and what enhances its diffusion through it causing precipitates?
from scrap metal or during welding and although at 300 C the driving force is enough, it is slow. Radiation enhances diffusion rates due to excess vacancy populations
Why does the zircaloy cladding goes brittle?
Because of Hydrogen absorption by cladding. Hydrogen precipitates into hybride phase (ZrHn) causing the material to go brittle
What are some sources of hydrogen in a PWR that can lead to cladding embrittlement?
- native hydrogen remaining in cladding after fabrication
- waterside corrosion of cladding
2.1 H produced by metal inside cladding by water entering fuel-cladding gap due to leaks - H added to water purposly to scavage oxygen
etc.
What happens to the solidus line when fast cooling?
It shifts and its larger the bigger the cooing rate.
What is the crystal structure of martensite? and what changes from its normal arrangement?
BCT (tetragonal body centered) but carbon atoms sit in octahedron spaces.
