Material science definitions Flashcards
elastic deformation
when material returns to original shape when the load/deforming force is removed
plastic deformation
permanent change in material when load/deforming force is removed
brittle
shows very little plastic behaviour, can’t absorb much energy before breaking
ductile
material that can withstand large strains without breaking, can be easily drawn into wires
hard
ability to resist impact/scratching
malleable
measure of plastic behaviour under compression, how easily a material can be worked, can be beaten into sheets
stiff
measure of resistance to shape
strong
material that is able to withstand a large stress without failing
tough
shows large amounts of plastic behaviour, can absorb a lot of energy without breaking
tensile/compressive stress
force per unit of cross-sectional area
tensile/compressive strain
extension/original length
spring constant
force per unit of extension during its proportional phase of deformation (F/x)
strength
maximum stress a material can withstand before PERMANENT DEFORMATION
breaking stress
stress at which material fails
Young modulus
measure of stiffness of a material, stress per unit of strain
limit of proportionality
point on graph when force isn’t proportional to extension anymore
yield point
when plastic behaviour starts, small increases in force –> large increase in extension
when is Hooke’s law obeyed
by an ideal spring + sample of metal up to limit of proportionality
dislocation
a gap in the metal lattice
definition for metal
positive ions in a sea of delocalised electrons
explain elastic behaviour in metals
space between ions gets larger/smaller but metallic bonds resist change from equilibrium length
