Calorimetric investigations of reactive metallic systems containing Sm, Mg, Zn and P

For a long time now, our group has been doing research on thermodynamic properties of selected alloy systems. Our interest has mainly centered on the determination of the enthalpies of formation of solid alloys by using calorimetric methods. This fundamental study is the basis for the modern material science which has the objective to tailor a material with a desired set of properties suitable for a given application. Indeed, the design of new alloys requires accurate knowledge of the thermodynamic stability of all relevant phases which may be integrated within CALPHAD formalism to calculate binary and ternary phase diagrams and phase transformation driving forces. In this contribution the difficulties encountered during the study by direct calorimetry of the formation enthalpies of different systems containing elements having high vapour pressure (Sm-Mg, Pd-Zn, Ti-Zn, Al-Ti-Zn and Ni-P) are presented; the experimental results are reported, discussed and compared with those available in literature. The investigation of these systems causes experimental problems due to intrinsic factors that may be unfavourable in finding an optimum condition for calorimetric runs (i.e. large difference in melting point between Al, Ti and Zn, high vapour pressure of Zn, Sm, Mg and P, the presence of peritectic reactions in the investigated systems, possible reaction between the elements and the crucibles in which we perform our calorimetric runs) that we faced and solved using suitable experimental solutions.