The results of calorimetric investigations in the section Pb-Bi-x-Mg-y-Sb-z
(mole ratio Bi:Mg: Sb=8:1:1) of the system Pb-Bi-Mg-Sb with Oelsen's metho
d are presented. The constructed space diagram and enthalpy isotherm diagra
m were used to determine integral mixing enthalpies for the investigated se
ction in the temperature interval 450-1100 K.