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Local chemical inhomogeneity enables superior strength-ductility-superelasticity synergy in additively manufactured NiTi shape memory alloys
Not provided.
Lattice Vibrations Boost Demagnetization Entropy in Shape Memory Alloy
Magnetocaloric (MC) materials present an avenue for chemical-free, solid state refrigeration through cooling via adiabatic demagnetization. We have used inelastic neutron scattering to measure the lattice dynamics in the MC material Ni 45 Co 5 Mn 36.6 In 13.4 . Upon heating across TC, the material exhibits an anomalous increase in phonon entropy of 0.17 0.04 k_B/atom, which is nine times larger than expected from conventional thermal expansion. We find that the phonon softening is focused in a transverse optic phonon, and we present the results of first-principle calculations which predict a strong coupling between lattice distortions and magnetic excitations.
Stretching-Induced Thermal Conductivity Change in Shape-Memory Polymer Composites
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Magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on ARCS at 300 K and 450 K
These sqw files were generated by combining all of the individual crystal angles scans using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html). The neutron incident energy for both temperatures was 50 meV. The file labeled 50meV_450K_All.sqw is the 450 K data and the file labeled 50meV_RT_All.sqw is for the 300 K data. The crystal was oriented such that HHL is in the scattering plane.
Strain glass state of magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on ARCS at 300 K
Combined inelastic neutron scattering data from ARCS on the strain glass state of Ni45Co5Mn36.6In13.4 measured at 300 K. Crystal was oriented with HHL in the scattering plane. To obtain a large Q-E volume the crystal was rotated in the beam and the individual angles were combined using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html).
Strain glass state of magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on SEQUOIA at 5 K
Combined inelastic neutron scattering data from SEQUOIA on the strain glass state of Ni45Co5Mn36.6In13.4 measured at 5 K. Crystal was oriented with HHL in the scattering plane. To obtain a large Q-E volume the crystal was rotated in the beam and the individual angles were combined using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html).
Effect of frustration on the soft phonon of a shape memory strain glass
Triple axis inelastic neutron data collected on the HB3 instrument at 220 K, 260 K, 300K, 350 K, 400 K, 450 K, 500 K.
Pseudoelastic Response of Ion-Implanted Nickel-Titanium Shape Memory Alloy: Combining Experimentation and Forward Modeling.
Abstract not provided.
Additively Manufacturing Nitinol Shape Memory Alloys for Advanced Actuator Designs
The objective of this research was to understand the role of feedstock production in the phase transformation behavior of additively manufactured Ni-Ti alloys for advanced actuator design. Industrial adoption of additively manufactured Ni-Ti alloys depends on the ability to produce repeatable phase transformation behavior, quantified here by the austenite to martensite transformation on heating. Small variations in the alloy composition may have a significant effect on the temperature at which this transformation occurs. This project showed that the powder characteristics play an important role in determining this behavior. Increases in the surface area per unit volume of the powder, either as a function of size distribution or morphology, have the effect of reducing the Ti content in the alloy through the formation of Ti-rich oxides on the powder surface, which has the effect of depressing the transformation temperature. Preferential Ni vaporization during additive manufacturing can partially offset this effect. To achieve repeatable results, it is important to understand the effect of powder oxidation, and to control the powder characteristics.
The Design and Development of Novel Heusler type Magnetic Shape Memory Alloys
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Characterization and Processing of High Temperature Shape Memory Alloys for Aerospace Applications
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Low-Temperature Mechanical Instabilities Govern High-Temperature Thermodynamics in the Austenite Phase of Shape Memory Alloy Constituents: Ab Initio Simulations of NiTi, NiZr, NiHf, PdTi, and PtTi
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Notes on the experimental measurement of fracture toughness of shape memory alloys
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Lightweight shape memory self-deployable structures for Gossamer applications
Currently, existing approaches for producing large, ultra-lightweight, deployable structures in space typically rely upon electro-mechanical mechanisms and mechanically expandable that are heavy, not stowage volume efficient, expensive and complex. Therefore, one of the major efforts at NASA and DoD has been to develop expandable structures characterized by low mass and small launch volume. As a result, space inflatable structures have emerged 9-10 years ago.