Dependence of fracture toughness on multiscale second phase particles in high strength Al alloys

AbstractPrecipitation-hardened aluminium alloys typically obtain their strength by forming second-phase particles, which, however, often have a negative effect on formability. To enable both lightweight construction and forming of complex parts such as body panels, high strength and formability are required simultaneously. Cluster hardening is a promising approach to achieve this. Here, we show that short thermal spikes, denoted as up-quenching, increase aging kinetics, which we attribute to the repeated process of vacancies being formed at high temperatures and retained when cooled to lower temperatures. Combined with further heat treatment, the up-quenching process promotes rapid and extensive cluster formation in Al-Mg-Si alloys, which in turn generates significant strengthening at industrially relevant heat treatment time scales. The high elongation values also observed are attributed to reduced solute depleted zones along grain boundaries.

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Effects of Zirconium and Yttrium Oxide on Mechanical and Oxidation Properties of Mo–3Si–1B–1Zr–1Y2O3 (wt.%) Alloy

Coatings ◽

10.3390/coatings10090833 ◽

2020 ◽

Vol 10 (9) ◽

pp. 833

Author(s):

Zhenping Guo ◽

Lei Wang ◽

Cheng Wang ◽

Qiuliang Li

Keyword(s):

Fracture Toughness ◽

Oxidation Resistance ◽

Yttrium Oxide ◽

Particle Dispersion ◽

Second Phase ◽

Fracture Toughness Test ◽

Dispersion Strengthening ◽

Fine Grain ◽

Fine Grain Strengthening ◽

Second Phase Particles

Mo–3Si–1B alloys with zirconium (1 wt.%) and yttrium oxide (1 wt.%) additives were fabricated by vibrating sintering techniques. The doped Mo–3Si–1B alloys consisted mainly of α-Mo, Mo3Si, and Mo5SiB2 (T2) phases. It was found that the grains were reduced, and the intermetallics particles were dispersed more homogeneously after the addition of Zr and Y2O3. The optimization in microstructure induced corresponding improvements in both fracture toughness and oxidation resistance. The predominant strengthening mechanisms were fine-grain strengthening and particle dispersion strengthening. In addition, fracture toughness test showed that the additions could improve the toughness of Mo–3Si–1B alloys, for which the toughening mechanism involved a crack trapping by α-Mo phases and extensive small second phase particles in the alloys. What should be paid attention to is the satisfactory oxidation resistance, both at medium-low temperature (800 °C) and high temperature (1200 °C) with doped additives.

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Texture, Microstructure and Second-Phase Particles in a Ti+P Interstitial Free (IF) Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.495-497.423 ◽

2005 ◽

Vol 495-497 ◽

pp. 423-428 ◽

Cited By ~ 1

Author(s):

Q.W. Jiang ◽

E.B. Zhao ◽

J.G. Zhang ◽

Y. Chen ◽

Gang Wang ◽

...

Keyword(s):

Cold Rolling ◽

High Strength ◽

Strain Ratio ◽

Warm Rolling ◽

Second Phase ◽

Rolled Sheet ◽

Interstitial Free ◽

If Steel ◽

Plastic Strain Ratio ◽

Second Phase Particles

The microstructure of Ti+P IF steel were studied after warm rolling, cold rolling and recrystallization using X-Ray, TEM and SEM. The results show that the characteristics of warm rolled sheet are the same as that of the cold rolled, but the texture displays different characteristics in the subsequent cold rolling and recrystallization because of the numerous second-phase particles. In this work, a Ti+P IF steel sheet with high strength and plastic strain ratio was obtained.

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The Room Temperature and Elevated Temperature Fracture Toughness Response of Alloy A-286

Journal of Engineering Materials and Technology ◽

10.1115/1.3443471 ◽

1978 ◽

Vol 100 (2) ◽

pp. 195-199 ◽

Cited By ~ 4

Author(s):

W. J. Mills

Keyword(s):

Fracture Toughness ◽

Room Temperature ◽

Elevated Temperatures ◽

Second Phase ◽

Surface Micromorphology ◽

Second Phase Particles ◽

The Matrix ◽

Temperature Fracture ◽

Increasing Temperature ◽

Base Superalloy

The elastic-plastic fracture toughness (JIc) response of precipitation strengthened Alloy A-286 has been evaluated by the multi-specimen R-curve technique at room temperature, 700 K (800°F) and 811 K (1000°F). The fracture toughness of this iron-base superalloy was found to decrease with increasing temperature. This phenomenon was attributed to a reduction in the materials’s strength and ductility at elevated temperatures. Electron fractographic examination revealed that the overall fracture surface micromorphology, a duplex dimple structure coupled with stringer troughs, was independent of test temperature. In addition, the fracture resistance of Alloy A-286 was found to be weakened by the presence of a nonuniform distribution of second phase particles throughout the matrix.

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Characteristics of Deposition Precipitation Process in Production of High Strength and Low Carbon Steel in FTSR

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.886.128 ◽

2014 ◽

Vol 886 ◽

pp. 128-131

Author(s):

Zhuo Fei Song ◽

Shan Shan Feng ◽

Yun Li Feng

Keyword(s):

Solid State ◽

Low Carbon Steel ◽

High Strength ◽

Dynamical Analysis ◽

Precipitation Process ◽

Second Phase ◽

Low Carbon ◽

Second Phase Particles ◽

Thermodynamics And Dynamics ◽

Hot Rolled

Precipitation characteristics of second phase in HSLC steel produced by FTSR technology have been researched by TEM and EDS in this article. And preliminary research of precipitation conditions of second phase particles in thermodynamics and dynamics have been took. The results indicate that: there’re second phase particles precipitated dispersively in hot rolled HSLC steels by FTSR technology. These particles mainly contain particles of Al2O3、MnS and AlN. Thermo dynamical analysis declares that most of the Al2O3 and all of the MnS、 AlN particles are precipitated in solid state. That’s why the precipitation process is slowed down by the diffusion velocity of the elements in solid, and thinner particles are precipitated while the material is in solid state than in liquid state.

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Notch fracture toughness of high-strength Al alloys

Materials & Design (1980-2015) ◽

10.1016/j.matdes.2012.07.031 ◽

2013 ◽

Vol 44 ◽

pp. 303-310 ◽

Cited By ~ 15

Author(s):

M. Vratnica ◽

G. Pluvinage ◽

P. Jodin ◽

Z. Cvijović ◽

M. Rakin ◽

...

Keyword(s):

Fracture Toughness ◽

High Strength ◽

Al Alloys

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Nucleation-Mediated Structural Refinement and Aluminium Alloy Design

Materials Science Forum ◽

10.4028/www.scientific.net/msf.519-521.191 ◽

2006 ◽

Vol 519-521 ◽

pp. 191-196 ◽

Cited By ~ 10

Author(s):

Barry C. Muddle ◽

Jian Feng Nie

Keyword(s):

Amorphous Matrix ◽

Thermomechanical Processing ◽

Nanocrystalline Structure ◽

Al Alloys ◽

Grain Structure ◽

Second Phase ◽

Structural Refinement ◽

Second Phase Particles ◽

Solid State Phase Transformation ◽

Structural Scale

Regardless of whether it is cast microstructure, the grain structure that is the product of thermomechanical processing or the nanoscale dispersions of strengthening second-phase particles, it is inescapable that the structural scale that controls mechanical properties in Al alloys is determined primarily by processes of nucleation during either solidification, recrystallisation or solid-state phase transformation. In those advanced alloys with bulk amorphous or nanocrystalline structure, production of an amorphous precursor is reliant on initial suppression of the nucleation of crystallisation, and subsequent controlled nucleation of dispersed nanocrystals within amorphous matrix. The processes of nucleation that control structural scale in modern Al alloys are briefly reviewed, with a focus on potential for further structural refinement and advances in properties.

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Optimization of Particle Size and Distribution by Hydrostatic Extrusion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.869 ◽

2007 ◽

Vol 561-565 ◽

pp. 869-872 ◽

Cited By ~ 2

Author(s):

Małgorzata Lewandowska ◽

Kinga Wawer

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Grain Size ◽

Aluminium Alloys ◽

Hydrostatic Extrusion ◽

Nanometer Scale ◽

Second Phase ◽

Size Refinement ◽

Second Phase Particles ◽

Fatigue And Fracture

Hydrostatic extrusion (HE) as a method of metals forming is known for about 100 years. Recently, it has been utilized as an efficient way of grain size refinement down to nanometer scale. In the case of engineering metals, HE processing alters not only grain size but also second phase particles such as intermetallic inclusions and precipitates. During HE processing, these particles significantly change their size, shape and spatial distribution. These changes are accompanied by improvement in properties of processed metals such as fatigue and fracture toughness. In the present work, changes of second phase particles induced by HE are described in a quantitative way for aluminium alloys. Their impact on mechanical properties is also discussed.

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Mismatch and misorientation at the precipitate/matrix interface in an Al-Zralloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075002 ◽

1983 ◽

Vol 41 ◽

pp. 242-243

Author(s):

Angus Porter ◽

Louise Makin ◽

Brian Ralph

Keyword(s):

High Strength ◽

Second Phase ◽

Exact Nature ◽

Matrix Interface ◽

Single Image ◽

Second Phase Particles ◽

The Matrix ◽

Lattice Planes ◽

Zr Alloy ◽

Zr Alloys

Much of the hardening of high strength aluminium alloys containing zirconium results from the precipitation of the metastable γ' (Al3Zr) phase (Ll2 structure, cube/cube related to the matrix). There exists some controversy in the literature as to the magnitude of the matrix (γ)-γ' misfit in Al-Zr alloys; the values reported range from 1% down to rather less than half this figure. In the present paper, the use of moire fringe imaging to study mismatch and misorientation between the γ and γ' lattice in a binary Al-Zr alloy will be considered. The advantages of this technique for the study of small second-phase particles are three-fold. The information obtained is specific to a single particle; the exact nature of the particle/matrix interface is unimportant, as long as the two lattices exhibit nearly coincident diffraction maxima; and mismatch and misorientation of particular sets of lattice planes can be determined from a single image.

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