Numéro
J. Phys. Colloques
Volume 43, Numéro C4, Décembre 1982
ICOMAT-82
International Conference on Martensitic Transformations
Page(s) C4-389 - C4-394
DOI https://doi.org/10.1051/jphyscol:1982457
ICOMAT-82
International Conference on Martensitic Transformations

J. Phys. Colloques 43 (1982) C4-389-C4-394

DOI: 10.1051/jphyscol:1982457

STRUCTURAL CHANGES IN INVAR IRON-PALLADIUM ALLOYS BEFORE THE f.c.c.- b.c.t. MARTENSITIC TRANSFORMATION

M. Foos, C. Frantz et M. Gantois

Laboratoire de Génie Métallurgique, Ecole Nationale Supérieure de la Métallurgie et de l'Industrie des Mines, Parc de Saurupt, 54000 Nancy, France


Abstract
In several iron-palladium alloys (25-32 at % Pd) metastable f.c.c. long range disordered austenite transforms into b.c.c. or b.c.t. martensite according to the Ms temperature is above or below the Curie temperature. In this last case, the austenite becomes tetragonal with a distribution of the c/a parameter as the temperature decreases. This phenomenon may be connected with the strong Invar effect present in these alloys and is characterized by special features in electron microscopy. As discussed in Fe3Pt alloys, such structural changes may be explained by shears of same magnitude on two {110} planes lying at 60° from each other and may be considered as precursor of the transformation of f.c.c. austenite into b.c.t. martensite.