Effects of liquid droplet volume and impact frequency on the integrity of Al alloy AW2014 exposed to subsonic speeds of pulsating water jets

Thermal aging of Ni-12.8 at. % A1 and Ni-12.7 at. % Si produces spatially homogeneous dispersions of cuboidal γ'-Ni3Al or Ni3Si precipitate particles arrayed in the Ni solid solution. We have used 3.5-MeV 58Ni+ ion irradiation to examine the effect of irradiation during precipitation on precipitate morphology and distribution. The nearness of free surfaces produced unusual morphologies in foils thinned prior to irradiation. These thin-foil effects will be important during in-situ investigations of precipitation in the HVEM. The thin foil results can be interpreted in terms of observations from bulk irradiations which are described first.Figure 1a is a dark field image of the γ' precipitate 5000 Å beneath the surface(∿1200 Å short of peak damage) of the Ni-Al alloy irradiated in bulk form. The inhomogeneous spatial distribution of γ' results from the presence of voids and dislocation loops which can be seen in the bright field image of the same area, Fig. 1b.

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A microscopic marker experiment study on high temperature oxidation of Ni-Al alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144085 ◽

1986 ◽

Vol 44 ◽

pp. 514-515

Author(s):

Shou-kong Fan

Keyword(s):

Transport Mechanism ◽

High Temperature Oxidation ◽

Transverse Section ◽

Al Alloy ◽

Metal Interface ◽

Electron Microscopic ◽

Temperature Oxidation ◽

Analytical Electron ◽

Microscopic Studies ◽

First Time

Transmission and analytical electron microscopic studies of scale microstructures and microscopic marker experiments have been carried out in order to determine the transport mechanism in the oxidation of Ni-Al alloy. According to the classical theory, the oxidation of nickel takes place by transport of Ni cations across the scale forming new oxide at the scale/gas interface. Any markers deposited on the Ni surface are expected to remain at the scale/metal interface after oxidation. This investigation using TEM transverse section techniques and deposited microscopic markers shows a different result,which indicates that a considerable amount of oxygen was transported inward. This is the first time that such fine-scale markers have been coupled with high resolution characterization instruments such as TEM/STEM to provide detailed information about evolution of oxide scale microstructure.

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Diffraction study on bainite of Cu-Al alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178161 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1006-1007

Author(s):

Delu Liu ◽

T. Ko

Keyword(s):

Diffraction Study ◽

Parent Phase ◽

Al Alloy ◽

Alloy Sample ◽

Bright Field Image ◽

Hexagonal System ◽

Iced Brine ◽

Diffraction Patterns ◽

Zone Pattern ◽

Stacking Structure

Structure of bainite in Cu-Al and Cu-Zn-Al alloys has been reported as 3R, 9R or 18R long period stacking structure (LPS) by X-ray and electron diffraction studies. In the present work, a Cu-25.5 (at)% Al alloy sample was heated at 900°C for 2 h then isothermally held at 450°C for 60 s before quenching into iced brine. FIG.1 shows a TEM bright field image of bainite plates (marked B) grown from grain boundary. The parent phase ( with DO3 structure ) has transformed to martensite (marked M ) during cooling from 450° C to 0°C. Both bainite and martensite plates have dense striations inside.Careful diffraction study on a JEOL 2000FX TEM with accelerating voltage 200 KV revealed (FIG.2) that the diffraction patterns contai_ning the same zone axis [001] ( hexagonal index ) or [111]c ( cubic index ) are from a bainite plate with obtuse V-shape. They are indexed as [010], [140], [130], [120], [230], [340] and [110] zone pattern for hexagonal system respectively.

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