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Flashcards in metals and alloys Deck (21):
1

What are metals at ambient temperature?

hard and lustrous
closely packed crystalline sturctures
opaque
conductors of heat and electricity

2

What is an alloy?

mixture of 2 or more metals

3

what is a binary alloy?

mixture of 2 metals

4

what is a ternary alloy?

mixture of 3 metals

5

What is an alloy system?

all possible combinations of an alloy

6

in molten state, what do metals display?

mutual solubility

7

What structure are metals?

regular crsytaline structure

8

What are metals composed of?

many small crystals called grains

9

what is a grain boundary?

where crystals abut their neighbour

10

when do grains stop growing?

when all melt metal consumed

11

what is heterogeneous nucleation?

many sites of nucleation
majority of dental application

12

what is homogeneous nucleation?

single site of nucleation
requires specialist equipment
metal so pure it requires 4 metal atoms to come together

13

how does grain size influence metals?

can influence physical properties

14

What techniques promote small grain size?

rapid solidification- lost wax technique
provision of extra nucleation sites- irradium

15

what factors affect grain size?

temperature of mould
shape of mould

16

What size of grain does slow cooling produce?

large grain

17

what size of grain does rapid cooling produce?

small grains

18

how can grain boundaries be visualised?

light reflecting microscope
polished metal surface
application of etching chemical

19

what is malleability?

the degree of compression in response to an applied compressive force

20

what are the three types of solid solutions that can be formed?

ordered solid- component metals have specific sites in common lattice
random solid- random sites in solid crystal lattice
interstitial solid- stoms of one lie in primary lattice sites of other

21

compared with pure metals what are solid solutions?

harder
stronger