The effects of hydrostatic pressure on the ductility of metals and alloys

A law governing the change in the ductility of metals and alloys under pressure is given: $$\begin{gathered} \left( {\frac{P}{{\sigma _n }}} \right) = \tfrac{1}{2}\frac{1}{{\sigma _n }}\frac{{d\sigma }}{{d\varepsilon }}\{ \varepsilon _{local} (P)^{\tfrac{3}{2}} - \varepsilon _{local} (O)^{\tfrac{3}{2}} \} + \tfrac{1}{3}\frac{1}{{\sigma _n }}\frac{{d\sigma }}{{d\varepsilon }}\{ \varepsilon _{local} (P) - \varepsilon _{local} (O)\} + \hfill ...