Mössbauer and electron microscopy study of martensitic transformations in an Fe-Mn-Mo alloy

Abstract

The kinetic, morphological, crystallographic, and magnetic characteristics of thermally induced martensites in Fe-13.4wt% Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Mössbauer spectroscopy. The experimental results reveal that two types of thermal-induced martensites, ɛ (hcp) and α′ (bcc) martensites, are formed in the as-quenched condition, and these transformations have athermal characters. Mo addition to the Fe-Mn alloy does not change the coexistence of ɛ and α′ martensites with the Mn content between 10wt% and 15wt%. Besides, Mössbauer spectra reveal a paramagnetic character with a singlet for the γ (fcc) austenite and ɛ martensite phases and a ferromagnetic character with a broad sextet for the α′ martensite phase. The volume fraction of α′ martensite forming in the quenched alloy is much more than that of the ɛ martensite.

Keywords

Fe-Mn alloy / molybdenum / martensitic transformation / scanning electron microscopy (SEM) / transmission electron microscopy (TEM) / Mössbauer spectroscopy

References

[1] Kirindi T., Dikici M. Microstructural analysis of thermally induced and deformation induced martensitic transformations in Fe-12.5wt% Mn-5.5wt% Si-9wt% Cr-3.5wt% Ni alloy. J. Alloys Compd., 2006, 407, 157.

[2] Sarı U., Aksoy Electron microscopy study of 2H and 18R martensites in Cu-11.92wt% Al-3.78wt% Ni shape memory alloy. J. Alloys Compd., 2006, 417, 138.

[3] Nishiyama Z. Martensitic Transformation, 1978 London, Academic Press

[4] Jun J.H., Choi C.S. The influence of Mn content on microstructure and damping capacity in Fe-(17–23)% Mn alloys. Mater. Sci. Eng. A, 1998, 252, 133.

[5] Durlu T.N. Effect of austenite grain size on ɛ martensite formation in an Fe-Mn-Mo alloy. J. Mater. Sci. Lett., 1997, 16, 320.

[6] Kirindi T., Güler E., Dikici M. Effects of homogenization time on the both martensitic transformations and mechanical properties of Fe-Mn-Si-Cr-Ni shape memory alloy. J. Alloys Compd., 2007, 433, 202.

[7] Martínez J., Cotes S.M., Cabrera A.F., Desimoni J., Fernández Guillermet A. On the relative fraction of ɛ martensite in γ-Fe-Mn alloys. Mater. Sci. Eng. A, 2005, 408, 26.

[8] Acet M., Schneider T., Gehrmann B., Wassermann E.F. The magnetic aspect of the γ-α and γ-ɛ martensitic transformation in Fe-Mn alloys. J. Phys. IV, 1995, 5, 379.

[9] Marinelli P., Fernández Guillermet A., Sade M. The enthalpy change of the hcp→fcc martensitic transformation in Fe-Mn-Co alloys: composition dependence and thermal cycling effects. Mater. Sci. Eng. A, 2004, 373, 1.

[10] Cotes S., Sade M., Fernández Guillermet A. Fcc/Hcp martensitic transformation in the Fe-Mn system: Experimental study and thermodynamic analysis of phase stability. Metall. Mater. Trans. A, 1995, 26, 1957.

[11] Cotes S., Fernández Guillermet A., Sade M. Phase stability and fcc/hcp martensitic transformation in Fe-Mn-Si alloys Part I. Experimental study and systematics of the M _s and A _s temperatures. J. Alloys Compd., 1998, 278, 231.

[12] Marinelli P., Baruj A., Cotes S., Fernández Guillermet A., Sade M. The γ↔α′ martensitic transformation in Fe-Mn and Fe-Mn-Co alloys: experiments, thermodynamic analysis and systematics of driving forces. Mater. Sci. Eng. A, 1999, 273–275, 498.

[13] Li H., Dunne D., Kennon N. Factors influencing shape memory effect and phase transformation behaviour of Fe-Mn-Si based shape memory alloys. Mater. Sci. Eng. A, 1999, 273–275, 571.

[14] Durlu T.N. The effect of deformation on γ-ɛ martensitic transformation in an Fe-Mn-Mo alloy. J. Mater. Sci., 1999, 34, 2887.

[15] Durlu T.N. Effect of γ↔ɛ cycles on the martensitic transformation characteristics of an Fe-Mn-Mo alloy. J. Mater. Sci. Lett., 1996, 15, 2134.

[16] Cotes S.M., Fernández Guillermet A., Sade M. Fcc/Hcp martensitic transformation in the Fe-Mn system: Part II. Driving force and thermodynamics of the nucleation process. Metall. Mater. Trans. A, 2004, 35, 83.

[17] Güler E., Kirindi T., Aktaş H. Comparison of thermally induced and deformation induced martensite in Fe-29% Ni-2% Mn alloy. J. Alloys. Compd., 2007, 440, 168.

[18] Lu X., Qin Z.X., Zhang Y.S., et al. Study of the paramagnetic-antiferromagnetic transition and the γ→ɛ martensitic transformation in Fe-Mn alloys. J. Mater. Sci., 2000, 35, 5597.

[19] Yang J.H., Chen H., Wayman C.M. Development of Fe-based shape memory alloys associated with face-centered cubic-hexagonal close-packed martensitic transformations: Part II. Transformation behaviour. Metall. Trans. A, 1992, 23, 1439.

[20] Mizrahi M., Cabrera A.F., Cotes S.M., et al. Distribution of Mn atoms in a substitutional bcc-FeMn solid solution. Hyperfine Interact., 2004, 156/157, 541.

[21] Cotes S.M., Cabrera A.F., Damonte L.C., et al. Phase transformations in Fe-Mn alloys induced by ball milling. Hyperfine Interact., 2002, 141/142, 409.

[22] Marinelli P., Baruj A., Pons J., et al. The enthalpy change of the hcp→fcc martensitic transformation in Fe-Mn alloys: composition dependence and effects of thermal cycling. Mater. Sci. Eng. A, 2002, 335, 137.

[23] Petrow Y.I., Shafranovsky E.A., Baldokhin Y.V., Kochetov G.A. On ferro- and antiferromagnetic ordering in ultrafine particle of Fe-Rich Fe-Ni and Fe-Mn alloys. J. Appl. Phys., 1999, 86, 7001.

[24] Martínez J., Aurelio G., Cuello G., et al. Mössbauer spectroscopy, dilatometry and neutron diffraction detection of the ɛ-phase fraction in Fe-Mn shape memory alloys. Hyperfine Interact., 2005, 161, 221.

[25] Cotes S.M., Cabrera A.F., Damonte L.C., et al. Magnetic properties of ball-milled Fe-Mn alloys. Phys. B, 2002, 320, 274.