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.