Objective
The project aims to clarify the effect of the high anisotropic temperature dependence of the crystal lattice parameters of Ni-Mn-Ga-X martensitic alloys on the crystal, magnetic and electronic structure and functional properties: thermal expansion, magnetoelasticity, superelasticity, magnetic and electrical properties. Scientific and technological objectives of the project: to carry out a complex experimental and theoretical fundamental study of the effect of cooling within wide temperature range from the 400K-4K on the crystalline, magnetic and electronic structures, as well as on functional and magnetic properties (magnetoelasticity, magnetoplasticity mechanical superelasticity, electric properties) in the single crystalline ferromagnetic martensites Ni-Mn-Ga-(X) with 5-layered modulated (5M) and non- modulated tetragonal (NMT) crystal lattice; basing on the strong anisotropic temperature dependent change in the martensite lattice parameters to clarify the correlation between temperature dependent structure evolution (crystalline, magnetic and electronic) and its dynamic response to the external fields. Characterization of the defect structure evolution (planar defects, staking faults, irregularity of the modulated structure), that affects twin boundary motion is an important part of the study. Project is based on the complex experimental methods of crystal and magnetic structure study: neutron and X-ray diffraction; scanning, optical and transmission electron microscopy, magnetisation and electronic structure study. These methods combined with the functional properties study (thermal, magnetic, magneto-mechanical, mechanical, electric), as well as with theoretical methods is combined to reach goal of the project. Expected results: - temperature dependence of the lattice parameters, interatomic distances within temperature range 400K- 4K for the 5M and NMT martensite; - clarification of the interrelation of the magnetic and crystal structure for the 5M and NMT martensites within temperature range 400-4K; - determination of the thermal expansion for 5M and NMT martensitic single crystals within range 400K-4K; - clarification of change in the functional properties (magnetic, mechanical, electric) in ferromagnetic 5M and NMT martensites with deep cooling down; - the basis for analysis of the diffraction data should be developed to analyze the crystal structures of modulated and non-modulated martensitic phases in Ni-Mn-Ga-(X) crystals , allowing for the structure disorder due to planar defects; - the physical grounds for creation of a new class of single crystalline thermoadaptors and thermocompensators with the specified thermal expansion will be developed for application in the airspace industry.
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Topic(s)
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ESPOO
Finland