Fully welded contact

For two porous components A and B in welded contact, the volume fractions of the components v_A, v_B satisfy

v_A + v_B = 1,   while the overall porosity is given by

= v_A_A + v_B_B,   where $\phi_A, \phi_B$ are respectively the porosities of the porous constituents A and B. The fractions of the total volume occupied by the solid components are $\bar{v}_A = v_A(1-\phi_A)$ and $\bar{v}_B(1-\phi_B)$, respectively. The solid components in A and B are individually pure, so that each porous constituent may be thought of as a microhomogeneous (or Gassmann) material.