Metals and Alloys

Question 1

Features of metals at ambient temperature?

Answer 1

hard, lustrous, closely packed crystalline structure, opaque and conductors

Question 2

What is an alloy?

Answer 2

mixture of two or more metals

Question 3

In molten state, what do metals display?

Answer 3

mutual solubility

Question 4

When metal cools, impurities enable metal atoms to deposit upon them which does what?

Answer 4

nucleate crystal growth

Question 5

What are crystals termed as?

Answer 5

grains

Question 6

When do grains grow until?

Answer 6

all melt metal consumed

Question 7

What is grain boundary?

Answer 7

crystals abut their neighbour

Question 8

Two types of nucleation

Answer 8

Heterogenous and Homogenous

Question 9

Feature of heterogenous nucleation

Answer 9

many sites of nucleation

Question 10

Feature of homogenous nucleation

Answer 10

single site of nucleation

Question 11

Factors influencing physical properties

Answer 11

grain size, temperature of mould and shape of mould

Question 12

What promotes a small grain size?

Answer 12

rapid solidification and extra nucleation sites

Question 13

Define ductility

Answer 13

maximum degree of extension in response to an applied tensil force

Question 14

Define malleability

Answer 14

maximum degree of compression in response to an applied compressive force

Question 15

What is a solid solution?

Answer 15

on cooling from molten component metals, metals remain soluble in each other

Question 16

3 types of solid solution

Answer 16

ordered, random and interstitial

Question 17

What is an ordered solid solution?

Answer 17

component metal atoms have specific sites in common lattice

Question 18

What is a random solid solution?

Answer 18

random sites in common crystal lattice

Question 19

What is an interstitial solid solution?

Answer 19

atoms of one lie within the primary lattice sites

Question 20

What does a plateau on a cooling curve indicate?

Answer 20

temperature constant during crystallisation

Question 21

What do cooling curves provide info on?

Answer 21

corrosion resistance

Question 22

On phage diagrams, what does a greater distance between solidus and liquidus indicate?

Answer 22

greater erosion

Question 23

What is the eutectic point?

Answer 23

where alloy components are insoluble in each other and specific point where crystallisation occurs

Question 24

Features of an eutectic alloy

Answer 24

behaves like a pure metal, a narrow melting range, narrow melting point lower than component metals and application as solders