Influence of Composition and Thermal Treatments on the Martensitic Transition of Cu-Al-Mn Alloys

E. Obradó; L. Mañosa; A. Planes

doi:doi:10.1051/jp4:1997536

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Numéro		J. Phys. IV France Volume 07, Numéro C5, November 1997 IV^th European Symposium on Martensitic Transformations


Page(s)		C5-233 - C5-238
DOI		https://doi.org/10.1051/jp4:1997536

IV^th European Symposium on Martensitic Transformations

J. Phys. IV France 07 (1997) C5-233-C5-238
DOI: 10.1051/jp4:1997536

Influence of Composition and Thermal Treatments on the Martensitic Transition of Cu-Al-Mn Alloys

E. Obradó, L. Mañosa and A. Planes

Departament d'Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Catalonia, Spain

Abstract
We have studied the martensitic transformation and the order-disorder transitions in two families of composition related Cu-Al-Mn crystals. X-ray diffraction and calorimetric measurements have been performed to characterize order-disorder transitions. The entropy change at the martensitic transition has been computed from calorimetric measurements. Results show that its magnitude depends only on the martensite structure which, in turn, depends on the electronic concentration e/a. We have obtained ΔS=1.51 +/- 0.05 J.mol^-1K^-1 for a transition to a 2H phase and ΔS=1.26 +/- 0.06 J.mol^-1K^-1 for a transition to a 18R structure. We discuss the possibility of a magnetic contribution to ΔS. Finally it is found that quenching has a marked influence on the martensitic transition temperature, but it does not affect the entropy change.