Metals I - C5 Flashcards
Define amorphous…
When metals cool quickly, the grains are disordered in structure.
Define crystalline…
When materials cool slowly, they can form whole crystals, like high-purity silicon.
Define polycrystalline…
A material has many crystals. When these cool, the grains grow out until they meet at the grain boundaries.
What is a grain?
A region of space occupied by a lattice.
What is a grain boundary?
A region of atomic mismatch between grains.
What is a lattice?
A regular structure of ions or particles.
In ceramics, stress is r….d and c…..d below the crack, causing bonds to be forced a….. . In metals, they are d…… meaning that cracks broaden, so metals deform p……., reducing stress.
Reflected, concentrated, apart, ductile, plastically.
Why can metals pack atoms closely together?
The bonds are non directional.
Why do metals stay together?
The bonds between the positive nuclei and the electrons are very strong.
Why are metals tough?
The positive ions can move anywhere so the metal simply changes shape.
Why are metals strong?
The electrostatic forces of attraction between the electrons and nuclei affect the strength and stiffness. The smaller the distance and greater the charge, the stronger the metal.
Why are metals ductile?
Ions can move past each other so there are no permanent bonds.
