Shape-memory hacks were fabricated in a single processing step ("one-time procedure") by a combination of tensile and bending deformation of a martensitic NiTi-wire. The hacks reversibly changed curvature on heating and cooling in a reproducible manner over 50 thermal cycles. This new type of intrinsic two-way shape memory effect was studied by subjecting the hacks to a beam of high-energy sync...

This work focuses on the stress-induced transformation in solutionized and overaged single-crystal NiTi alloys. The potential role of detwinning on the recoverable strains was investigated both theoretically and also with temperature-cycling experiments. The detwinning is the growth of one variant within a martensite in expense of the other. It is shown that the experimental recoverable strains...

Laser powder bed fusion (L-PBF)-processed 17-4 PH stainless steel (SS) generally exhibits a non-equilibrium microstructure consisting mostly of columnar δ-ferrite grains and substantial fraction retained austenite martensite, contrary to SS wrought with fully martensite structure coarse grains. Despite the different microstructures L-PBF SS, post-processing is typically performed using conventi...

Microstructural morphology is known to have a significant impact on the mechanical properties of dual-phase steels. A fine ferrite grain size and random distribution small second phase islands are desirable provide superior isotropic compared banded that typical for this type steel. rapid alloy prototyping (RAP) facility has been used investigate three different DP 800 variants by systematicall...

The TA1 welded joints with different heat inputs were obtained by a fiber laser and their microstructure, mechanical properties corrosion resistance in simulated saliva solution studied. results show that the microstructure fusion zone (FZ) is needle-like ?? martensite lath-shape martensite, of heat-affected (HAZ) zigzag ? phase. With increase input, volume fraction decrease coarsened FZ, but t...

Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformat...

Experimental tests performed on superelastic shape-memory alloys (SMAs) show a significant dependence of the stress–strain relationship on the loading–unloading rate, coupled with a not negligible oscillation of the material temperature. This feature is of particular importance in view of the use of such materials in earthquake engineering, where the loading rate affects the structural response...

Diffusionless phase transitions are at the core of the multifunctionality of (magnetic) shape memory alloys, ferroelectrics and multiferroics. Giant strain effects under external fields are obtained in low symmetric modulated martensitic phases. We outline the origin of modulated phases, their connection with tetragonal martensite and consequences for their functional properties by analysing th...

The cofactor conditions, introduced in James and Zhang(2005), are conditions of compatibility between phases in martensitic materials. They consist of three subconditions: (i) the condition that the middle principal stretch of the transformation stretch tensor U is unity (λ2 1⁄4 1), (ii) the condition a UcofðU IÞn1⁄4 0, where the vectors a and n are certain vectors arising in the specification ...