Lecture 6

Question 1

study slide 3

Answer 1

ye

Question 2

what are the metal crystal imperfections?

Answer 2

1. point defects (vacancies)–imploding
2. interstitial atoms (point defects)–>bulging
3. dislocations (linear defects)

Question 3

tetrakaidecaherdron–equiaxed grain structure, most ideal SA:vol ratio?

Answer 3

mehbe

Question 4

the objective of alloying is to optimize properties

Answer 4

ye

Question 5

types of dental alloys?

Answer 5

cast dental alloys–>melted a cast, e.g. gold crowns

wrought dental alloys–melted at first but then mechanically shaped into their final forms )e.g. ortho wires and dental implants)

Question 6

what are the conditions for solid solubility?

Answer 6

1. must have same crystal structure
2. must have similar atom size (difference of <15%)
3. valence–>same valence is favourble
4. chem affin: lesser affin forms SS

Question 7

know slide 20

Answer 7

ye

Question 8

what is the lever rule?

Answer 8

percent weight of the solid phase: Xs= (wo-wl)/(ws-wl)

percent weight liq phase: Xl=(ws-wo)/ws-wl

Question 9

study slide 22

Answer 9

YE!!!!

Question 10

The temperature at which the eutectic composition melts is lower than the melting temperature of either Cu or Ag
There is no solidification temperature range at the eutectic composition

Answer 10

ye