Vasiliy D. Buchelnikov

Modelling the phase diagram of magnetic shape memory Heusler alloys

We have modelled the phase diagram of magnetic shape memory alloys of the Heusler type by using the phenomenological Ginzburg–Landau theory. When fixing the parameters by realistic values taken from experiment we are able to reproduce most details of, for example, the phase diagram of Ni2+xMn1−xGa in the (T, x) plane. We present the results of ab initio calculations of the electronic and phonon properties of several ferromagnetic Heusler alloys, which allow one to characterize the structural changes associated with the martensitic instability leading to the modulated and tetragonal phases. From the ab initio investigations emerges a complex pattern of the interplay of magic valence electron per atom numbers (Hume–Rothery rules for magnetic ternary alloys), Fermi surface nesting and phonon instability. As the main result, we find that the driving force for structural transformations is considerably enhanced by the extremely low lying optical modes of Ni in the Ni-based Heusler alloys, which interfere with the acoustical modes enhancing phonon softening of the TA2 mode. In contrast, the ferromagnetic Co-based Heusler alloys show no tendency for phonon softening.

Phase transitions in Ni2+xMn1-xGa with a high Ni excess

Ferromagnetic shape memory alloys Ni

Heating of metallic powders by microwaves: Experiment and theory

_{2+x}

Monte Carlo simulations of the magnetocaloric effect in magnetic Ni–Mn–X (X = Ga, In) Heusler alloys

Mn

Shape Memory Alloys: A Summary of Recent Achievements

_{1-x}

Fundamental Aspects of Magnetic Shape Memory Alloys: Insights from Ab Initio and Monte Carlo Studies

Ga were studied in the range of compositions

Phase transitions in intermetallic compounds Ni-Mn-Ga with shape memory effect

0.16 \le x \le 0.36

Composition-Dependent Basics of Smart Heusler Materials from First- Principles Calculations

. Experimental phase diagram, constructed from differential scanning calorimetry, transport and magnetic measurements, exhibits distinctive feature in a compositional interval

Quaternary Ni?Mn?In?Y Heusler alloys: a way to achieve materials with better magnetocaloric properties?

0.18 \le x \le 0.27

Crystal structures of Ni2MnGa from density functional calculations

, where martensitic and magnetic transitions merge in a first-order magnetostructural phase transition ferromagnetic martensite