Energy of Small Angle Tilt Boundary in Al

The critical inconsistency on the small angle boundary energy between the theoretical prediction of Read-Shockley model and the experimental results was discussed. The plots of the ratio between boundary energyEand the tilt angleθagainst logθshow different tendency between the EAM simulated and the experimental results. The first principles calculations on the small angle tilt boundary energy on Al ⟨100⟩ direction were performed. Still the calculation sizes of the model are limited, the obtained values are located between the EAM simulated and the experimetal results.

Рентгеноструктурный анализ эпитаксиальных слоев со свойствами дислокационного фильтра

An approach to instant testing of epitaxial films with a sharp decrease in the threading dislocation density is proposed. High-resolution X-ray diffractometry, including reciprocal space mapping, has been used. The structure of GaAs/Si(001) heterosystems with low-temperature GaAs layers has been analyzed. A decrease in the density of threading dislocations in the GaAs film with the formation of a small-angle boundary has been detected.

Characterization of Dislocations Found in an Array at a Mixed Character Small Angle Boundary of a Cross Rolled and Annealed Aluminium Sample

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Formation of a Small-Angle Boundary During Annealing of a Cross Rolled Aluminium Sample

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

The Effect on the Surface of Ti-5Al-2Sn-2Zr-4Mo-4Cr by Laser Shock Peening

Under the terrible environment in the aero-engine, the blade, made of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy, is prone to result in fatigue failure. So improving the titanium alloy performance is becoming very significant. In this paper, the microstructure and microhardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared by XRD, TEM and microhardness test. The XRD tests pointed out that LSP generated the microstrains and grains refinement in the material surface. The TEM results indicated that great high density dislocations were generated and evolved into the dislocation wall, small-angle boundary and large-angle boundary. The nanocrystallites were formed and became more and more uniform after 4GW/cm2. The grains nanocrystallization in the surface layer helps to improve the material performance. The microhardness test result showed that LSP could increase the hardness by 20 percent or so. And the affected depth is about 700μm.

Evolution of a Small Angle Boundary from a Perfect Lattice During Annealing of a Cross Rolled Aluminium Sample

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Effects of Transformation Stress and Deformation before Austenitization on Nucleation of Intragranular Bainite

Intragranular bainite is known to be effective to develop toughness greatly in steels. Effects of aging below eutectoid temperature before austenitization, the deformation before solution treatment and the duration of solution treatment on nucleation of intragranular bainite have been examined. In the austenite (γ) region where carbide pre-existed, the stress due to inverse transformation, ferrite (α) to γ, would be introduced into fine austenitized region with lower transus temperature to γ, resulting in the introduction of stable small-angle boundary at high temperatures acting as the nucleation site for intragranular bainite lath. Deformation of α by cold rolling before solution treatment enhances the nucleation of intragranular bainite, suggesting that the above γ region through the inverse transformation is easily deformed by the hardened neighboring α. In the deformed γ region, small-angle boundary would be more easily introduced, acting as nucleation site for intragranular bainite. Intragranular bainite lath grew and hardness decreased by prolonging the duration of solution treatment, indicating that transformation stress introduced by the pre-treatment was influenced by solution treatment. The effect of sulfur addition on formation of intragranular bainite was also analyzed.

Boundary layers and stress concentration in the circular shearing of annular thin films

This work addresses a generalization of Dean's classical problem, which sought to explain how an annular thin elastic plate buckles under uniform shearing forces applied around its edges. We adapt the original setting by assuming that the outer edge is radially stretched while the inner rim undergoes in-plane rotation through some small angle. Boundary-layer methods are used to investigate analytically the deformation pattern which is set up and localized around the inner hole when this angle reaches a well-defined critical wrinkling value. Linear stability theory enables us to identify both the critical load and the preferred number of wrinkles appearing in the deformed configuration. Our asymptotic results are compared with a number of direct numerical simulations.

Structure and misorientation angle distributions of (001) twist grain boundaries in Bi2Sr2Ca1Cu2Oy/Ag composite tapes processed in different oxygen partial pressures

We investigated the relationship between the structure and misorientation angle of (001) twist grain boundaries in Bi2Sr2Ca1Cu2Oy/Ag composite tapes processed in different oxygen partial pressures (PO2 = 0.01, 0.21, and 1 atm). Large-angle misoriented twist boundaries (>10°) essentially had no amorphous layers at the interface, and the misorientation angles of these boundaries mostly corresponded to low-energy misorientations. This large-angle misoriented boundary structure was independent of PO2. Small-angle misoriented twist boundaries (<10°), on the other hand, corresponded to high-energy misorientations and sometimes had amorphous layers at the interface. The population of the small-angle boundary with an amorphous layer was very low in the tape processed in PO2 = 1 atm. This suggests that high PO2 during the heat treatment is effective in the improvement of grain coupling, and hence, to increase critical current density.