ENTHALPIES OF FORMATION FOR THE AL-Y AND AL-Y-NI INTERMETALLIC COMPOUNDS

A method of liquid-metal solution calorimetry has been applied for the rmochemical research of intermetallic compounds in the Al-Y and Al-Y-N i systems. Heats of dissolution for the following intermetallics: Al3Y ; Al2Y; Al2Y3 and Al4YNi in liquid Al were measured with the help of a high-temperature isoperibol Calvet-type calorimeter. Using these valu es, standard molar enthalpies of formation for the listed compounds we re calculated: Delta(f,298)H(m) degrees(Al3Y) = -185.6 +/- 7.2 kJ mol( -1); Delta(f,298)H(m) degrees(Al2Y) = -160.4 +/- 7.5 kJ mol(-1); Delta (f,298)H(m) degrees(Al2Y3) = -234.4 +/- 19.5 kJ mol(-1); Delta(f,298)H (m) degrees(Al4Y-Ni) = -361.5 +/- 12.0 kJ mol(-1) Comparisons have bee n made with some available experimental data and theoretical values ca lculated from the Miedema model with the help of parameters recommende d in different papers.