Coherent twin boundaries (CTBs) in nano-twinned materials could improve crack resistance. However, the role of the CTBs during crack penetration has never been explored at atomic scale. Our in situ observation on nano-twinned Ag under a high resolution transmission electron microscope (HRTEM) reveals the dynamic processes of a crack penetration across the CTBs, which involve alternated crack ti...

Superelastic NiTi (51.0 at.% Ni) specimens reinforced with 0, 10 and 20 vol.% TiC particles were deformed under uniaxial compression while neutron diffraction spectra were collected. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. The evolution of austenite/martensite phase fractions and of elastic strains in the reinforcing TiC particles and the...

Depending on the starting equilibrium temperature, the application of a magnetic field on a sample of Ni–Mn–Sn produces sample heating or cooling during adiabatic experiments. The competition between endothermal and exothermal effects is observed close to the martensite-to-austenite magnetostructural phase transition. A model assuming the coexistence of two phases and a field dependence of thei...

The texture of cold-rolled and heat-treated TiNi sheet has been measured and designated as {110}(1i0)p. This material has been used in thermal fatigue tests during and after which the anisotropy and development of several thermomechanical properties, such as transformation temperatures and strains, have been measured. Furthermore, the resulting changes of texture after thermal fatigue are prese...

Shape Memory Alloys (SMAs) undergo stress and temperature induced reversible diffusionless crystalline phase transformations between a high synmaetry phase (austenite) stable at high tenlperatures and low stresses, and a low symmetry phase (martensite) stable at low temperatures and high stresses. Unusual macroscopic effects arise from these crystallographic changes, chiefly shape memory and su...

An Fe-16MndSi alloy exhibits a good one-way and a little two-way shape memories by the stress induced y + E martensitic transformation and its reversion on heating and cyclic thermal y 2 E transformations, respectively. An intrusion of small amount of a' martensite at the initial shape change is not found to deteriorate the one-way memory and rather enhance the two-way memory. The two Fe-Mn-C a...

Martensitic steels form a material class with a versatile range of properties that can be selected by varying the processing chain. In order to study and design the desired processing with the minimal experimental effort, modeling tools are required. In this work, a full processing cycle from quenching over tempering to mechanical testing is simulated with a single modeling framework that combi...

Dual phase steels with different martensite volume fraction and morphology were tensile tested at a temperature range of 25 to 5500C. Stress-strain curves of all steels showed serration flow at temperatures of 250 and 3500C, and smooth flow at the other temperatures. Both yield and ultimate tensile strengths increased with increasing testing temperature up to about 450<sup...

A macroscopic symmetry group describing the superconducting state of an orthorhombically twinned crystal of YBCO is introduced. This macroscopic symmetry group is different for different symmetries of twin boundaries. Josephson tunneling experiments performed on twinned crystals of YBCO determine this macroscopic symmetry group and hence determine the twin boundary symmetry (but do not experime...

We propose layer-by-layer growth mechanisms to account for planar defect generation leading to kinked polytype nanowires. Cs-corrected scanning transmission electron microscopy enabled identification of stacking sequences of distinct polytype bands found in kinked nanowires, and Raman spectroscopy was used to distinguish polytype nanowires from twinned nanowires containing only the 3C diamond c...