|ΔA||=||A0||2αΔT||areal (or superficial) expansion|
|ΔV||=||V0||3αΔT||volumetric (or cubical) expansion|
Thermal expansion is a small, but not always insignificant effect. Typical coefficients are measured in parts per million per kelvin (10−6/K). That means your typical classroom meter stick never varies in length by more than a 100 µm in its entire lifetime — probably never more than 10 µm while students are using it.
Some materials expand differently in different directions, notably graphite and wood (lumber).
ΔV = βV0ΔT
coolant overflow tanks in cars
Liquids have higher expansivities than solids
β ~ 10−3/K, 3α ~ 10−5/K
That's why a liquid in glass themometer works
ethyl aclohol 1120 × 10−6/K, mercury 181 × 10−6/K
The alcohol is colred red to look like wine.
glass 3(8.5 × 10−6/K) = 25.5 × 10−6/K
|ΔV||=||V0||βΔT||volumetric (or cubical) expansion|
[check out the gas laws]
behavior of gases is more complicated, gases will expand as much as pressure will allow
|PV||=||nRT||ideal gas law|
Plutonium undergoes more phase transitions at ordinary pressures than any other element. As plutonium is heated it transforms through six different crystal structures before melting — α [alpha], β [beta], γ [gamma], Δ [delta], Δ′ [delta prime], and ε [epsilon]. Physical properties like density and thermal expansion vary significantly from phase to phase making it one of the more difficult metals to machine and work. The metallurgy of plutonium is best left to the experts.
Notes form LLNL that must be paraphrased. "One of plutonium's unique physical properties is that the pure metal exhibits six solid-state phase transformations before reaching its liquid state, passing from alpha, beta, gamma, delta, delta-prime, to epsilon. Large volume expansions and contractions occur between the stable room-temperature alpha phase and the element's liquid state. Another unusual feature is that unalloyed plutonium melts at a relatively low temperature, approximately 640 ℃, to yield a liquid of higher density than the solid from which it melts. In addition, the elastic properties of the delta face-centered cubic (fcc) phase of plutonium are highly directional (anisotropic). That is, the elasticity of the metal varies widely along different crystallographic directions by as much as a factor of six to seven."