Lattice Softening in Fe3Pt Exhibiting Three Types of Martensitic Transformations
نویسندگان
چکیده
We have investigated the relation between the softening of elastic constants and martensitic transformation in Fe3Pt, which exhibits various kinds of martensitic transformation depending on its long-range order parameter S. The martensite phases of the examined alloys are BCT (S = 0.57), FCT1 (S = 0.75, c/a < 1) and FCT2 (S = 0.88, c/a > 1). The elastic constants C′ and C44 of these alloys decrease almost linearly with decreasing temperature. Although the temperature coefficient of C′ decreases as S increases, C′ at the transformation temperature is the smallest in the alloy with S = 0.75, which transforms to FCT1. This result implies that softening is most strongly related to the formation of the FCT1 martensite with tetragonality c/a < 1 among the three martensites.
منابع مشابه
Transformation Plasticity and Toughening
Analysis of the dynamic evolution of multilevel structure during martensitic transformations provides kinetics-based constitutive relations for transformation plasticity. Application in numerical modeling of ductile fracture by microvoid-softening-induced shear localization, in conjunction with metallographic study of crack-tip processes, identifies transformation toughening mechanisms operatin...
متن کاملElectron-Phonon Interaction and Phonon Softening in Systems with Magnetovolume Instabilities
The interrelation of Invar and martensitic behaviour in transition metal alloys like Fe65Ni35 is discussed on the basis of ab initio calculations for stoichiometric systems like Fe3Ni. We also examined face centered cubic iron as a model system for Antiinvar which like Invar shows a pronounced phonon softening. Neutron scattering experiments on Invar systems have shown that the TA1 phonon mode ...
متن کاملDynamic stabilization of cubic AuZn
A recently developed temperature-dependent effective potential method is employed to study the martensitic phase transformation in AuZn. This method is based on ab initio molecular dynamics and allows to obtain finite-temperature lattice vibrational properties. We show that the transversal acoustic TA2[110] mode associated with the phase transition is stabilized at 300 K. Temperature evolution ...
متن کاملStructure fragmentation in Fe-based alloys by means of cyclic martensitic transformations of different types
The effect of martensite transformations of different types on the misorientation of austenite crystalline lattice, which characterizes the degree of structure fragmentation, was investigated for Fe-Ni and Fe-Mn alloys. As a result of multiple face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. transformations, an austenite single-crystalline specimen is transformed in a polycrysta...
متن کاملA Finite Element Model for Martensitic Thin Films
A finite element approximation of the thin film limit for a sharp interface bulk energy for martensitic crystals is given. The energy density models the softening of the elastic modulus controlling the low-energy path from the cubic to the tetragonal lattice, the loss of stability of the tetragonal phase at high temperatures and the loss of stability of the cubic phase at low temperatures, and ...
متن کامل