Atomistic simulations are performed to study the structure and geometrical limit of nanoscale twins in NiTi shape memory alloys. We analyze compound twins as narrow as 1 nm, involving a few atomic layers. A novel nanotwinned structure is found, forming through the martensitic transformation of sublattices. We predict the temperatures of phase transformation, which are consistent with experiment...

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...

A significant carbon diffusion mobility acceleration as a result of cyclic γ↔ε martensitic transformations in iron-manganese alloy is determined by one- and two-dimensional structure defects of ε-martensite with face-centered close-packed lattice. Such defects (dislocations, low angle sub-boundaries of dislocations, chaotic stacking faults) were formed during cyclic γ↔ε martensitic transformati...

We report on the magnetic and martensitic transformation properties of Co39Ni33Al28 ferromagnetic shape memory alloy ribbons. We found that the phase formation of Co39Ni33Al28 is strongly dependent on the method of preparation. The conventional as-cast ingot sample contains a large amount of the γ phase embedded in the primary β phase, while melt-spun ribbons contain the pure β phase. Co39Ni33A...

We report results of ab-initio calculations of the ferromagnetic Heusler alloy Ni-Mn-Ga. Particular emphasis is placed on the stability of the low temperature tetragonal structure with c/a = 0.94. This structure cannot be derived from the parent L21 structure by a simple homogeneous strain associated with the soft elastic constant C ′. In order to stabilise the tetragonal phase, one has to take...

The article presents a theory able to calculate various phenomena of martensitic unelasticity as well as of dislocation plasticity. The theory is based on the structure-analytical conception. The developed lnethodology accounts for such fundamental phenomena as kinetics of martensite crystals growth; influence of temperature, stress and neutron radiation; influence of nonhomogeucons strain of d...

Within the framework of a systems approach, the design of a high performance stainless steel integrated processing/structure/property/performance relations with mechanistic computational models. Using multicomponent thermodynamic and diffusion software platforms, the models were integrated to design a carburizable, secondary-hardening, martensitic stainless steel for advanced gear and bearing a...

Using molecular dynamics simulations with an embedded-atom interatomic potential, we study the effect of chemical composition and uniaxial mechanical stresses on the martensitic phase transformation in Ni-rich NiAl alloys. The martensitic phase has a tetragonal crystal structure and can contain multiple twins arranged in domains and plates. The transformation is reversible and is characterized ...

Deuterium thermal desorption spectra were investigated on the samples of austenitic stainless steel 18Cr10NiTi preimplanted at 100 K with deuterium ions in the dose range from 3 × 10(15) to 5 × 10(18) D/cm(2). The kinetics of structural transformation development in the implantation steel layer was traced from deuterium thermodesorption spectra as a function of implanted deuterium concentration...