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Flashcards in Dental Alloys Deck (27)
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1

pure gold is -- for use in the mouth

too soft

2

-- form natural barrier to the movement of dislocations

grain boundaries

3

solute atom -- directly for the solvent atom at the normal lattice site of the crystal

substitutes

4

alloys are liquid -- liquidous line

above

5

-- can crystalize at a constant temp (have a melting point) but not over a range of temp

partial solid solution

6

defect known as -- weakens the crystalline structure

dislocation

7

dislocations are frequent in -- such as gold

face centered cubic (FCC)

8

FCCs:

Ag, Au, Cu, Pt, Pd,

9

why is a fine grain desirable in a dental metal

high strength
but
high corrosion
low ductility

10

rate of cooling controls --

grain size

11

few nuclei, larger grains --

slow cooling

12

more nuclei, smaller grains from --

rapid cooling and add grain refiners

13

restricting dislocation motion makes material --

stronger

14

3 ways to restrict dislocation

control grain size, alloying, strain hardening

15

gold crown alloy: parent atom = gold (95%), common substitute atom

Cu

16

substitute atoms have same --

crystal structure

17

atomic size of parent and substitute atoms are within -- of each other

15%

18

parent and substitute atoms must have same --

valency

19

alloys are solid -- the solidus line

below

20

alloys are -- between the liquids and solidus lines

mixture of solid and liquid

21

wide melting ranges make -- difficult to cast

alloys

22

examples of wide melting ranges

Au-Ag-Pt
Ag-Pd

23

partial solid solution: liquids and solidus lines meet at --

eutectic composition

24

partial solid solution behaviors like a -- at eutectic composition

pure metal

25

alloy at eutectic composition

eutectic alloy

26

eutectic alloy has a melting temp --

lower than either pure components

27

eutectic alloy's -- can be utilized to form low melting temp materials such as solders to join other metals

low melting pt