Diffusivity

In heat transfer analysis, thermal diffusivity (symbol: ) is the ratio of thermal conductivity to volumetric heat capacity. where:k is thermal conductivity (SI units: watts per metre-kelvin, W∙m-1∙K-1)ρcp is the volumetric heat capacity (density kg∙m-3 times specific heat capacity J∙kg-1K-1; SI units: joules per cubic metre-kelvin, J∙m-3∙K-1)The SI units for thermal diffusivity are square metres per second or m2∙s-1.
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(n.)
Tendency to become diffused; tendency, as of heat, to become equalized by spreading through a conducting medium.
  

the temperature depedent rate that an impurity diffuses.

the tendency of materials to spread out (mix with their surroundings), and measurements thereof.

B: (Fisika) keterbauran; difusivitas
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