Enthalpies of formation of selected Fe2YZ Heusler compounds

• Enthalpies of formation of selected Fe2YZ were measured by drop calorimeters.
• Enthalpies of Fe2YZ are in general less negative than that of Co2YZ.
• Fe2YZ is less ordered when compared with Co2YZ.
• Result of L21 structured compounds agrees with first principles data.
• Lattice parameters were consistent with literature data.

Standard enthalpies of formation at 298 K of selected ternary Fe-based Heusler compounds Fe2YZ (Y = Co, Cu, Mn, Ni, Ti, V; Z = Al, Ga, Si, Ge, Sn) were measured by high temperature direct synthesis calorimetry. The measured enthalpy of formation (in kJ mol of atoms−1) for compounds of Heusler structure is Fe2MnSi (−25.6 ± 1.5); Fe2VSn (−3.7 ± 3.1); for the inverse-Heusler structure, Fe2CoGa (−14.1 ± 1.9); Fe2CoSi (−37.4 ± 1.8); Fe2CoGe (−8.9 ± 2.0); for the B2 structure, Fe2CoAl (−23.4 ± 2.2); Fe2CuAl (−23.4 ± 2.1); Fe2MnAl (−9.1 ± 1.8); Fe2NiAl (−30.9 ± 2.4); Fe2NiGa (−14.6 ± 0.4); Fe2NiSi (−26.7 ± 1.1); Fe2VGa (−30.0 ± 2.9) and for the A1 structure Fe2MnGa (−5.6 ± 2.3). Values are compared with those from published first principles calculations and the extended semi-empirical model of Miedema. To provide further verification of the stable crystal structure, several alloys were prepared by arc melting and annealing. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) were applied to examine the samples. Differential scanning calorimetry was used to determine phase transformation temperatures.