Materials Science: 10 Things Every Engineer Should Know: Thing 2

The diffusivity (D) of copper in a brass alloy is 10-20 m2/s at 400 °C. The activation energy for copper diffusion in this system is 195 kJ/mol. The diffusivity at 600 °C is _____________.

2.93 x 10-17

As an indication of how "close packed" the aluminum (FCC) crystal structure is, ________ of the volume of the unit cell is occupied by the aluminum atoms.

74

The gas constant, R, is equal to _______________ times the Boltzmann's constant, k.

Avogadro's number

The energy needed to produce a single vacancy, Ev, is the same as the activation energy, Q.

False

The vacancy and the interstitial are two common types of point defects in metallic crystal structures.

True

Solid-state diffusion occurs in the face centered cubic structure of aluminum by individual aluminum atoms hopping into _______________ sites.

adjacent vacant

The Arrhenius relationship shows that the rate of chemical reactions increases _______________ temperature.

exponentialy whit

Aluminum metal is an example of a ______________.

face-centered cubic crystal structure

The diffusion coefficient is defined by _______________.

first

The Arrhenius plot is a linear set of data points in which the logarithm of rate is plotted against the ____________.

inverse temperature

The activation energy, Q, for a chemical reaction is indicated by the _______________ of the Arrhenius plot.

slope

The gas constant, R, is an appropriate term for equations describing gas phases and ________________ processes.

solid-state