Characterization of Grain Boundary‐Engineered Aluminum–Magnesium Alloys

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

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Structural analysis of a Σ5 grain boundary in YBa2Cu3O7δ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015054x ◽

1993 ◽

Vol 51 ◽

pp. 942-943

Author(s):

J.-Y. Wang ◽

Y. Zhu ◽

A.H. King ◽

M. Suenaga

Keyword(s):

Grain Boundary ◽

Lattice Mismatch ◽

Weak Link ◽

Coincidence Site Lattice ◽

Large Angle ◽

Dislocation Core ◽

Superconducting Order Parameter ◽

Outstanding Problem ◽

Transmission Electron

One outstanding problem in YBa2Cu3O7−δ superconductors is the weak link behavior of grain boundaries, especially boundaries with a large-angle misorientation. Increasing evidence shows that lattice mismatch at the boundaries contributes to variations in oxygen and cation concentrations at the boundaries, while the strain field surrounding a dislocation core at the boundary suppresses the superconducting order parameter. Thus, understanding the structure of the grain boundary and the grain boundary dislocations (which describe the topology of the boundary) is essential in elucidating the superconducting characteristics of boundaries. Here, we discuss our study of the structure of a Σ5 grain boundary by transmission electron microscopy. The characterization of the structure of the boundary was based on the coincidence site lattice (CSL) model.Fig.l shows two-beam images of the grain boundary near the projection. An array of grain boundary dislocations, with spacings of about 30nm, is clearly visible in Fig. 1(a), but invisible in Fig. 1(b).

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Multifactor mathematical model of criticality of welding process of products from aluminum- magnesium alloys

10.36652/0042-4633-2020-3-12-18 ◽

2020 ◽

pp. 12-18

Author(s):

F.A. Urazbahtin ◽

A.YU. Urazbahtina

Keyword(s):

Mathematical Model ◽

Magnesium Alloy ◽

Magnesium Alloys ◽

Welding Process ◽

Welding Equipment ◽

Equipment Operation ◽

Aluminum Magnesium Alloys ◽

Aluminum Magnesium Alloy ◽

Welding Materials

A multifactor mathematical model of the welding process of products from aluminum-magnesium alloys, consisting of 71 indicators that assess the quality of the weld, the welding process, costs, equipment operation and quality of the welded material. The model can be used to control and optimize the welding process of products from aluminum-magnesium alloys. Keywords welding, products, aluminum-magnesium alloy, indicators, process parameters, welding equipment, welding materials, electrode sharpening, lining [email protected]

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