Mechanical Properties

· For a low molecular weight material, such as a metal, the elastic response is directly related to the interatomic potential.
· The average separation of the atoms, <r>, is r₀ , and the slope of the force/distance curve at r₀ gives the "spring constant" of the bond.
(dF/dr)₀= (d²V(r) /dr²)₀
· A unit area plane normal to the stress axis has about N = (1/r₀²) "bonds" connecting it to adjacent planes.
· An applied stress, σ, causes the inter- planar spacing to change by Δr = (r - r₀) yielding a microscopic strain, ε= (Δ r/r_0.)

From: Callister, Wiley (1994)