Refinement of second-phase particles and grain structures of 2219 Al Cu alloy forgings using an improved thermomechanical treatment process

The thermomechanical treatment of a 2A12 aluminum alloy was researched and the influence of pre-ageing on microstructure and hardness was analyzed emphatically. The results reveal that the hardness of specimen increases when they are pre-aged, the hardness value rises at first and then decreases, reaching the maxmum value when pre-aged at 180°C×30min . After plastically deformed at 450°C, the hardness keeps on increasing, and the grains are equiaxed polygon structure. After all the workpieces are aged in the end, the small particles of the second phase precipitates completely and disperses within the original phase matrix, the particles interact with dislocations in upper state that formed during plastic deformation and lead to a great increase in hardness compared with as-received. the best pre-aging parameter is 180°C×30min.

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Effects of Excessive Zr Content and Ultrasonic Treatment on Microstructure and Mechanical Properties of Al-Zn-Mg-Cu Alloy

Metals ◽

10.3390/met11040632 ◽

2021 ◽

Vol 11 (4) ◽

pp. 632

Author(s):

Cheng Li ◽

Shusen Wu ◽

Shulin Lü ◽

Jianyu Li ◽

Longfei Liu ◽

...

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Ultrasonic Vibration ◽

Ultrasonic Treatment ◽

Second Phase ◽

Cu Alloy ◽

Cu Alloys ◽

Microstructure And Mechanical Properties ◽

Second Phase Particles ◽

Properties Of Materials

The Zr element is one of the important grain refiners for 7xxx series Al-Zn-Mg-Cu alloys, but the effect of Zr content more than 0.15 wt.% needs to be deeply investigated under the action of ultrasonic vibration. In this study, the effects of Zr contents (0.1 to 0.25 wt.%) on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy were studied. The results showed that Zr element could refine grains, but when the Zr content was greater than 0.15 wt.%, the grain size was not uniform, the number of second phase particles increased, and the segregation of components became more serious. It was found that after ultrasonic treatment, the grain-size inhomogeneity was greatly improved, and the Zr content could be added up to 0.2 wt.%. When the Zr content is equal or lower than 0.2 wt.%, ultrasonic treatment can effectively improve the mechanical properties of materials by refining grains and weakening segregation. However, when the Zr content is up to 0.25 wt.%, the effect is getting worse.

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Polishing process effect on the image of dispersed precipitates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112646 ◽

1984 ◽

Vol 42 ◽

pp. 534-535

Author(s):

C.T. Hu ◽

C.W. Allen

Keyword(s):

Matrix Material ◽

Specimen Preparation ◽

Second Phase ◽

Precipitate Particle ◽

Polishing Process ◽

Second Phase Particles ◽

The Matrix ◽

Surface Profiles ◽

Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

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Analytical Electron Microscopy Study of Second-Phase Particles in 7075 and 7475 Aluminum Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118618 ◽

1985 ◽

Vol 43 ◽

pp. 348-349

Author(s):

M. Raghavan ◽

J. Y. Koo ◽

J. W. Steeds ◽

B. K. Park

Keyword(s):

Aluminum Alloys ◽

Silicon Oxide ◽

Analytical Electron Microscopy ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Partial Substitution ◽

Second Phase ◽

X Ray ◽

Second Phase Particles ◽

Almost All

X-ray microanalysis and Convergent Beam Electron Diffraction (CBD) studies were conducted to characterize the second phase particles in two commercial aluminum alloys -- 7075 and 7475. The second phase particles studied were large (approximately 2-5μm) constituent phases and relatively fine ( ∼ 0.05-1μn) dispersoid particles, Figures 1A and B. Based on the crystal structure and chemical composition analyses, the constituent phases found in these alloys were identified to be Al7Cu2Fe, (Al,Cu)6(Fe,Cu), α-Al12Fe3Si, Mg2Si, amorphous silicon oxide and the modified 6Fe compounds, in decreasing order of abundance. The results of quantitative X-ray microanalysis of all the constituent phases are listed in Table I. The data show that, in almost all the phases, partial substitution of alloying elements occurred resulting in small deviations from the published stoichiometric compositions of the binary and ternary compounds.

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Development of Second-Phase Particles during Solidification and Homogenization of Aluminium Alloy AlMn1

Practical Metallography ◽

10.3139/147.110556 ◽

2019 ◽

Vol 56 (5) ◽

pp. 317-341 ◽

Cited By ~ 1

Author(s):

O. Engler ◽

K. Kuhnke ◽

K. Westphal

Keyword(s):

Aluminium Alloy ◽

Second Phase ◽

Second Phase Particles

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Evidence of hydrogen trapping at second phase particles in zirconium alloys

Scientific Reports ◽

10.1038/s41598-021-83859-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Christopher Jones ◽

Vidur Tuli ◽

Zaheen Shah ◽

Mhairi Gass ◽

Patrick A. Burr ◽

...

Keyword(s):

Density Functional ◽

Secondary Ion Mass Spectrometry ◽

Zirconium Alloys ◽

Nuclear Industry ◽

Second Phase ◽

Hydrogen Trapping ◽

Functional Theory ◽

Second Phase Particles ◽

Hydrogen Isotope Ratios ◽

Dft Modelling

AbstractZirconium alloys are used in safety–critical roles in the nuclear industry and their degradation due to ingress of hydrogen in service is a concern. In this work experimental evidence, supported by density functional theory modelling, shows that the α-Zr matrix surrounding second phase particles acts as a trapping site for hydrogen, which has not been previously reported in zirconium. This is unaccounted for in current models of hydrogen behaviour in Zr alloys and as such could impact development of these models. Zircaloy-2 and Zircaloy-4 samples were corroded at 350 °C in simulated pressurised water reactor coolant before being isotopically spiked with 2H2O in a second autoclave step. The distribution of 2H, Fe and Cr was characterised using nanoscale secondary ion mass spectrometry (NanoSIMS) and high-resolution energy dispersive X-ray spectroscopy. 2H− was found to be concentrated around second phase particles in the α-Zr lattice with peak hydrogen isotope ratios of 2H/1H = 0.018–0.082. DFT modelling confirms that the hydrogen thermodynamically favours sitting in the surrounding zirconium matrix rather than within the second phase particles. Knowledge of this trapping mechanism will inform the development of current understanding of zirconium alloy degradation through-life.

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