ENTHALPIES OF FORMATION OF SOLID SM-AL ALLOYS

A direct isoperibolic differential calorimeter was used to measure the formation heats of the Sm-Al intermetallic compounds. X-ray powder di ffraction, optical and scanning electron microscopy and electron probe microanalysis were used to check the composition of the samples. The following values of Delta(f)H(0) for the different compounds were obta ined in the solid state at 300 K: Sm2Al, = -38.0+/-2 kJ (mol atoms)(-1 ); SmAl, -49.0+/-2 kJ (mol atoms)(-1); SmAl2, -55.0+/-2 kJ (mol atoms) (-1); SmAl3,-48.0+/-2 kJ (mol atoms)(-1). The results are discussed an d compared with earlier experimental data.