This paper describes an experimental study of stress-induced martensitic phase transformation in the SMA Nickel-Titanium. The rich local thermo-mechanical interactions that underlie transformation are examined using three-dimensional Digital Image Correlation (strain fields) and infrared imaging (thermal fields). We quantify the complex local interactions between released/absorbed latent heat a...

A ferrite–austenite 12CrNi2 alloy steel additively manufactured by laser melting deposition (LMD) was heat treated direct quenching (DQ) and tempering inter-critical (TIQ) at 800 °C for enhancing its strength–ductility balance. Both heat-treated steels have the martensite–ferrite dual-phase (DP) microstructures. The volume fractions of martensite in two are nearly similar (~ 85 vol%), while siz...

A significant variant selection is reported in isothermal martensite formed on the surface of an Fe-30% Ni sample. The selection phenomenon is modelled using different descriptions of the martensitic phase transformation. In particular, matrices based on the phenomenological theory of martensite crystallography, the Jaswon and Wheeler distortion, and the continuous face centred cubic-body centr...

In order to discuss the advent of the magnetic-field-induced strains for a single crystal Fe22:0Ni51:5Ga26:5 shape memory alloy, the magnetic easy axis in the 14M martensite phase and the magnetocrystalline anisotropy constant K have been investigated. From the data on the spontaneous thermal expansion and the magnetization curves, the magnetic easy axis of the 14M martensite phase was determin...

The atomic configurations at macrotwin interfaces between microtwinned martensite plates in Ni65Al35 material are investigated using high resolution transmission electron microscopy (HRTEM). The observed structures are interpreted in view of possible formation mechanisms of these interfaces. A distinction is made between cases in which the microtwins, originating from mutually perpendicular {11...

A continuum thermodynamics formulation for micromagnetics coupled with mechanics is devised to model the evolution of magnetic domain and martensite twin structures in ferromagnetic shape memory alloys. The theory falls into the class of phase-field or diffuseinterface modeling approaches. In addition to the standard mechanical and magnetic balance laws, two sets of micro-forces and their assoc...

We provide an extended Peierls–Nabarro (P–N) formulation with a sinusoidal series representation of generalized stacking fault energy (GSFE) to establish flow stress in a Ni2FeGa shape memory alloy. The resultant martensite structure in Ni2FeGa is L10 tetragonal. The atomistic simulations allowed determination of the GSFE landscapes for the (111) slip plane and 2 1⁄2 101 ; 2 1⁄2 110 ; 6 1⁄2 211...

This research focuses on the stability of three metastableβ titanium alloys – Ti-10V-1Fe-3Al (T i −1013), Ti-10V-2Cr-3Al (T i −102Cr 3) and Ti-10V-2Fe-3Al-B (T i −1023B). In the first stage of the work, new β+ (α+β) heat treatment schemes were designed on the basis of Thermo-Calc® simulations and previous research work and carried out to such an extent that the β phase stability is tuned to the...

Flash processing is a new heat treatment process being developed to produce steel with relatively high strength and ductility. It involves rapidly heating steel sheet or strip to a temperature in the austenite range and quenching; the entire thermal cycle takes place within 15 seconds. The resulting microstructure is fine and difficult to resolve using standard metallographic techniques. In thi...

Thermodynamically consistent, three-dimensional (3D) phase field approach (PFA) for coupled multivariant martensitic transformations (PTs), including cyclic PTs, variant– variant transformations (i.e., twinning), and dislocation evolution is developed at large strains. One of our key points is in the justification of the multiplicative decomposition of the deformation gradient into elastic, tra...