Point Defects (Leaving Cert Engineering): Flashcards
📚Flashcards
Practise the cards
15 cards from this deck
ShowHide
Practise the cards
15 cards from this deck
What are crystal lattice structures?
What are crystal lattice structures?
Organised arrangements of atoms in metals
What are defects in metals?
What are defects in metals?
Structural imperfections in crystal lattice
What are point defects?
What are point defects?
Imperfections at individual atomic positions in crystal
Scale of point defects
Scale of point defects
Smallest scale of defects in crystalline materials
Dimensionality of point defects
Dimensionality of point defects
Zero-dimensional (occur at specific atomic positions)
Properties affected by point defects
Properties affected by point defects
Strength, hardness, and ductility
What are vacancy defects?
What are vacancy defects?
Atoms missing from expected positions in crystal lattice
Effect of vacancy defects on surrounding material
Effect of vacancy defects on surrounding material
Surrounding atoms distort inward to fill the gap
What are substitution defects?
What are substitution defects?
Foreign atoms replace parent atoms in lattice positions
Effect of larger foreign atoms in substitution
Effect of larger foreign atoms in substitution
Create compressive stress, increase hardness, reduce ductility
Effect of smaller foreign atoms in substitution
Effect of smaller foreign atoms in substitution
Generate tensile stress, soften material, increase deformation
What are interstitial defects?
What are interstitial defects?
Foreign atoms occupy spaces between normal atomic positions
Why interstitial defects are problematic
Why interstitial defects are problematic
Increase hardness, reduce ductility, make material more brittle
What point defects disrupt
What point defects disrupt
Regular atomic bonding patterns within crystal structure
Effect of high defect concentrations
Effect of high defect concentrations
Unpredictable mechanical properties, unsuitable for critical use