The thermochemical behavior of some binary shape memory alloys by high temperature direct synthesis calorimetry

• Published in: Journal of alloys and compounds 2011-04, Vol.509 (17), p.5256-5262
• Main Authors: Meschel, S.V., Pavlu, J., Nash, P.
• Format: Article
• Language: English
• Subjects: Alloys; Calorimetry; Condensed matter: structure, mechanical and thermal properties; Enthalpy of formation; Exact sciences and technology; Ferrous alloys; Intermetallic compounds; Intermetallics; Mathematical models; Nickel titanides; Physics; Shape memory alloys; Synthesis; Thermal properties of condensed matter; Thermal properties of crystalline solids; Thermodynamic properties; Titanium base alloys; Titanium compounds
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.01.152

► We studied 14 shape memory alloys. ► The enthalpies of formation and structure characteristics are summarized. ► Theoretical predictions by ab initio calculations compare better with experimental measurements than Miedema's semi empirical model. The standard enthalpies of formation of some shape memory alloys have been measured by high temperature direct synthesis calorimetry at 1373 K. The following results (in kJ/mol of atoms) are reported: CoCr (−0.3 ± 2.9); CuMn (−3.7 ± 3.2); Cu 3Sn (−10.4 ± 3.1); Fe 2Tb (−5.5 ± 2.4); Fe 2Dy (−1.6 ± 2.9); Fe 17Tb 2 (−2.1 ± 3.1); Fe 17Dy 2 (−5.3 ± 1.7); FePd 3 (−16.0 ± 2.7); FePt (−23.0 ± 1.9); FePt 3 (−20.7 ± 2.3); NiMn (−24.9 ± 2.6); TiNi (−32.7 ± 1.0); TiPd (−60.3 ± 2.5). The results are compared with some earlier experimental values obtained by calorimetry and by EMF technique. They are also compared with predicted values on the basis of the semi empirical model of Miedema and co-workers and with ab initio calculations when available. We will also assess the available information regarding the structures of these alloys.