671 research outputs found
Complexion-mediated martensitic phase transformation in Titanium
The most efficient way to tune microstructures and mechanical properties of metallic alloys lies in designing and using athermal phase transformations. Examples are shape memory alloys and high strength steels, which together stand for 1,500 million tons annual production. In these materials, martensite formation and mechanical twinning are tuned via composition adjustment for realizing complex microstructures and beneficial mechanical properties. Here we report a new phase transformation that has the potential to widen the application window of Ti alloys, the most important structural material in aerospace design, by nanostructuring them via complexion-mediated transformation. This is a reversible martensitic transformation mechanism that leads to a final nanolaminate structure of α″ (orthorhombic) martensite bounded with planar complexions of athermal ω (a–ω, hexagonal). Both phases are crystallographically related to the parent β (BCC) matrix. As expected from a planar complexion, the a–ω is stable only at the hetero-interface
Instability of dilute granular flow on rough slope
We study numerically the stability of granular flow on a rough slope in
collisional flow regime in the two-dimension. We examine the density dependence
of the flowing behavior in low density region, and demonstrate that the
particle collisions stabilize the flow above a certain density in the parameter
region where a single particle shows an accelerated behavior. Within this
parameter regime, however, the uniform flow is only metastable and is shown to
be unstable against clustering when the particle density is not high enough.Comment: 4 pages, 6 figures, submitted to J. Phys. Soc. Jpn.; Fig. 2 replaced;
references added; comments added; misprints correcte
Noninvasive detection of a ruptured aneurysm at a basilar artery fenestration with submillimeter multisection CT angiography
The criterion standard for the detection of intracranial aneurysms is
digital subtraction angiography. MR imaging and CT provide good accuracy
in the evaluation of brain arteries and aneurysms. We herein report a case
of a ruptured aneurysm at a basilar artery fenestration. The diagnosis was
assessed with 16-row multisection CT angiography and was confirmed by
using digital subtraction angiography. The patient was successfully
treated with coil placement
Initial-state effects in scanned-energy-mode photoelectron diffraction
By a combination of experimental data [from the Ni (111) (2×2)-K structure], model calculations, and simple formal theory, it shown that a strong initial-state effect exists in backscattering photoelectron diffraction, which can be ascribed to the parity of the emitted photoelectron source wave field. Unlike the initial-state effect recently discussed in forward scattering photoelectron (and Auger electron) diffraction, which is a spherical wave effect only present due to the close proximity of the emitter and scatterer, this parity effect in the backscattering geometry exists even in the lowest order approximation of the scattering, i.e. the plane wave approximation
Mesoscopic motion of atomic ions in magnetic fields
We introduce a semiclassical model for moving highly excited atomic ions in a
magnetic field which allows us to describe the mixing of the Landau orbitals of
the center of mass in terms of the electronic excitation and magnetic field.
The extent of quantum energy flow in the ion is investigated and a crossover
from localization to delocalization with increasing center of mass energy is
detected. It turns out that our model of the moving ion in a magnetic field is
closely connected to models for transport in disordered finite-size wires.Comment: 4 pages, 2 figures, subm. to Phys.Rev.A, Rap.Co
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