Relationship of the elastic and nonlinear acoustic properties of the antiferromagnetic fccFe60Mn40

Influence of chemical composition and magnetic effects on the elastic properties of fcc Fe–Mn alloys

“…The experimentally obtained bulk modulus values were calculated from the measured reduced elastic modulus values using a linear dependence of Poisson's ratio on the Mn content, obtained from ab initio calculations of the elastic constants of DLM fcc Fe-Mn alloys [16] assuming crystallographic isotropy and using the Voigt-Reuss-Hill method [51] to determine the shear modulus (white pentagons) as well as using a mean Poisson's ratio of 0.25 (black pentagons). The Poisson's ratios calculated using the linear dependence are consistent with the data from Lenkkeri and Levoska [48] (À6.7% deviation) and Cankurtaran et al [49] (+1.3% deviation). Taking the dependence of Poisson's ratio on the Mn content into account, the experimentally determined bulk modulus decreases from 143[±34] GPa at $23 at.% Mn to 105[±12] GPa at $39 at.% Mn.…”

“…Furthermore, and most importantly, the effect of elastic anisotropy on the indentation modulus according to Nix [54] and Kooi et al [55] is not large, even for highly anisotropic materials. Based on the good agreement between the present nanoindentation results and published bulk data [48,49], a minor influence of residual stresses is inferred, as well as the deposition geometry on the elastic properties reported here.…”

“…5. Furthermore, calculated bulk moduli for magnetically ordered (AFM, 1 blue triangles; FM, green circles) and disordered (red squares) fcc Fe-Mn random alloys as well as bulk data from Lenkkeri and Levoska [48] (open star) and Cankurtaran et al [49] (filled star) are presented. The magnetic state of the magnetically disordered fcc Fe-Mn random alloys is described using the DLM model [50].…”

Magnetic contribution to the interdiffusion coefficients in bcc (α) and fcc (γ) Fe-Ni alloys

“…Thus, the magnetic contribution to the free energy of vacancy migration will be negative for Ni compositions less than ϳ78 pct and positive for Ni compositions greater than ϳ78 pct. Other Invar alloys, such as Fe 65 (Ni 1-x Mn x ) 35 , [44] Fe 60 Mn 40 , [45,46] Co 46 Mn 54 , [47] etc., also show a behavior of elastic constants similar to that of the Fe-Ni Invar alloy. Therefore, it is possible for these Invar alloys that the magnetic contribution to the free energy of vacancy migration below the Curie temperatures is also negative.…”

Temperature and magnetic-field dependence of the elastic constants of Ni-Mn-Al magnetic Heusler alloys

“…This behavior is in contrast with that displayed by the NiMn-Ga ferromagnetic system which, in the absence of magnetic field, shows no significant change in any elastic moduli at the Curie point. 13 We note that deviations from Debye behavior have been observed in antiferromagnetic systems such as chromium 30 and Mn-Invar alloys 31,32 below their Néel temperatures.…”