Material science definitions

Question 1

elastic deformation

Answer 1

when material returns to original shape when the load/deforming force is removed

Question 2

plastic deformation

Answer 2

permanent change in material when load/deforming force is removed

Question 3

brittle

Answer 3

shows very little plastic behaviour, can’t absorb much energy before breaking

Question 4

ductile

Answer 4

material that can withstand large strains without breaking, can be easily drawn into wires

Question 5

hard

Answer 5

ability to resist impact/scratching

Question 6

malleable

Answer 6

measure of plastic behaviour under compression, how easily a material can be worked, can be beaten into sheets

Question 7

stiff

Answer 7

measure of resistance to shape

Question 8

strong

Answer 8

material that is able to withstand a large stress without failing

Question 9

tough

Answer 9

shows large amounts of plastic behaviour, can absorb a lot of energy without breaking

Question 10

tensile/compressive stress

Answer 10

force per unit of cross-sectional area

Question 11

tensile/compressive strain

Answer 11

extension/original length

Question 12

spring constant

Answer 12

force per unit of extension during its proportional phase of deformation (F/x)

Question 13

strength

Answer 13

maximum stress a material can withstand before PERMANENT DEFORMATION

Question 14

breaking stress

Answer 14

stress at which material fails

Question 15

Young modulus

Answer 15

measure of stiffness of a material, stress per unit of strain

Question 16

limit of proportionality

Answer 16

point on graph when force isn’t proportional to extension anymore

Question 17

yield point

Answer 17

when plastic behaviour starts, small increases in force –> large increase in extension

Question 18

when is Hooke’s law obeyed

Answer 18

by an ideal spring + sample of metal up to limit of proportionality

Question 19

dislocation

Answer 19

a gap in the metal lattice

Question 20

definition for metal

Answer 20

positive ions in a sea of delocalised electrons

Question 21

explain elastic behaviour in metals

Answer 21

space between ions gets larger/smaller but metallic bonds resist change from equilibrium length