metals and alloys

Question 1

What are metals at ambient temperature?

Answer 1

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

Question 2

What is an alloy?

Answer 2

mixture of 2 or more metals

Question 3

what is a binary alloy?

Answer 3

mixture of 2 metals

Question 4

what is a ternary alloy?

Answer 4

mixture of 3 metals

Question 5

What is an alloy system?

Answer 5

all possible combinations of an alloy

Question 6

in molten state, what do metals display?

Answer 6

mutual solubility

Question 7

What structure are metals?

Answer 7

regular crsytaline structure

Question 8

What are metals composed of?

Answer 8

many small crystals called grains

Question 9

what is a grain boundary?

Answer 9

where crystals abut their neighbour

Question 10

when do grains stop growing?

Answer 10

when all melt metal consumed

Question 11

what is heterogeneous nucleation?

Answer 11

many sites of nucleation

majority of dental application

Question 12

what is homogeneous nucleation?

Answer 12

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

Question 13

how does grain size influence metals?

Answer 13

can influence physical properties

Question 14

What techniques promote small grain size?

Answer 14

rapid solidification- lost wax technique

provision of extra nucleation sites- irradium

Question 15

what factors affect grain size?

Answer 15

temperature of mould

shape of mould

Question 16

What size of grain does slow cooling produce?

Answer 16

large grain

Question 17

what size of grain does rapid cooling produce?

Answer 17

small grains

Question 18

how can grain boundaries be visualised?

Answer 18

light reflecting microscope
polished metal surface
application of etching chemical

Question 19

what is malleability?

Answer 19

the degree of compression in response to an applied compressive force

Question 20

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

Answer 20

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

Question 21

compared with pure metals what are solid solutions?

Answer 21

harder

stronger