Experimental and DFT characterization of η′ nano-phase and its interfaces in Al Zn Mg Cu alloys

Cao, Fuhua; Zheng, Jianting; Jiang, Yong; Chen, Bin; Wang, Yiren; Hu, Tao

doi:10.1016/j.actamat.2018.10.045

Cited by 138 publications

(17 citation statements)

References 57 publications

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“…It has been well established that the precipitation in the Al-Zn-Mg(-Cu) alloys is caused by diffusional nucleation followed by effective growth [6,79]. As discussed above (Section 4.1), the TiB2/Al interfaces are the favorable sites for nucleation of the interphase.…”

Section: Preferential Tib 2 /Al Interfaces For Suppressing the Interphase Precipitationmentioning

confidence: 92%

“…Age-hardenable Al alloys (e.g., 2xxx, 6xxx and 7xxx series) have been widely applied as structural materials in aerospace and automobile industries, due mainly to their high specific strength and excellent processability [1][2][3]. Commonly, one of the most effective strengthening mechanisms involves precipitation hardening, i.e., a homogenous distribution of nanosized precipitates originating from solid-state precipitation reactions during aging treatments [4][5][6]. In addition, micron-(or submicron-) sized reinforcement particles (MRPs), such as SiC and B4C, have successfully been introduced to Al alloys, providing an alternative approach to further enhance their mechanical performance, particularly in case high Young's modulus is necessary [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

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Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

Addad

et al. 2020

Acta Materialia

192

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The effects of nanosized reinforcement particles on precipitation reactions in age-hardenable Al alloy matrix composites have been largely unknown. In this work, an Al-Zn-Mg-Cu matrix composite reinforced with uniformly distributed TiB2 nanoparticles was successfully produced.The solid-soluted, peak-aged and overaged materials were then characterized, at the atomic scale using (high-resolution) scanning transmission electron microscopy, to provide a fundamental insight into the interface precipitation. Our results demonstrated that the facetted TiB2 nanoparticles have a significant impact on the precipitation in matrix areas adjacent to the TiB2/Al interfaces. The interfaces after solid-solution treatment are tightly-bonded and oxide-free, and display two orientation relationships (ORs): the well-reported [2 1 � 1 � 0]TiB 2 //[101]Al, (0001)TiB 2 //(1 � 11)Al (OR1) and the new [21 � 1 � 0]TiB 2 //[101]Al, (011 � 0)TiB 2 //(111 � )Al (OR2). The interface 2precipitates (i.e. interphase) having the size of several tens of nanometers were formed after ageing and were determined to be (Zn1.5Cu0.5)Mg phase. Their formations were only related to the initial OR1 and OR2 where the mutual ORs between the TiB2, interphase and Al matrix were further developed. Periodically spaced misfit dislocations were revealed at the semi-coherent TiB2/Al interfaces, which are generally considered beneficial to the heterogeneous precipitation. They not only reduced nucleation energy barrier, but also acted as short-circuit diffusion paths for transporting solute atoms and vacancies, accelerating growth rate. However, the growth of interphase at the interface parallel to close-packed {111} Al planes was suppressed by the ultralow accommodation factor. In addition, such an interface precipitation reduced the mismatch of the TiB2/Al interface, increasing the overall coherency and being potential for effective interface strengthening.

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Section: Preferential Tib 2 /Al Interfaces For Suppressing the Interphase Precipitationmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

Addad

et al. 2020

Acta Materialia

192

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“…This makes it difficult to precisely determine the g¢/matrix interfacial energy. Based on DFT, Cao et al [45] have predicted interfacial energies of~44 and 190 mJ/m 2 for the coherent and semi-coherent interfaces, respectively. Hence in the present work, an optimal value of 0.1 J/m 2 has been used.…”

Section: Model Prediction Of G¢ Precipitationmentioning

confidence: 99%

Modelling the Age-Hardening Precipitation by a Revised Langer and Schwartz Approach with Log-Normal Size Distribution

Zhao

Gouttebroze

et al. 2020

Metall Mater Trans A

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A new numerical modelling approach integrating the Langer and Schwartz approach and log-normal particle size distribution has been developed to depict the precipitation kinetics of age-hardening precipitates in Al alloys. The modelling framework has been implemented to predict the precipitation behavior of the key secondary phases in 6xxx and 7xxx Al alloys subjected to artificial aging. The simulation results are in good agreement with the available experimental data in terms of precipitate number density, radius, and volume fraction. The initial shape parameter of the log-normal size distribution entering the modeling framework turns to play an important role in affecting the later-stage evolution of precipitation. It is revealed that the evolution of size distribution is not significant when a small shape parameter is adopted in the modelling, while an initial large shape parameter will cause substantial broadening of the particle size distribution during aging. Regardless of the magnitude of shape parameter, a broadening of the particle size distribution as predicted by the present model is in agreement with experimental observations. It is also shown that large shape parameter will accelerate the coarsening rate at later aging stage, which induces fast decreasing of number density and increased growth rate of mean/critical radius. A comparison to the Euler-like multi-class approach demonstrates that the integration of more realistic log-normal distribution and Langer and Schwartz model make the present modelling faster and equivalently accurate in precipitation prediction.

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“…The semi-coherent η phase has been considered to be one of the major strengthening precipitates in the Al-Zn-Mg-Cu alloy. The crystal structure of η phase was hexagonal with lattice parameters of a = 0.496 nm and c = 1.40 nm [11,12].η phase was an equilibrium phase in Al-Zn-Mg-Cu alloys, and its crystal structure was hexagonal with lattice parameters of a = 0.5221 nm and c = 0.8567 nm [13,14]. GP zones and meta-stable η phase have been considered to play a dominant role on the strengthening of the alloy.…”

Section: Introductionmentioning

confidence: 97%

Precipitate Behavior, Mechanical Properties and Corrosion Behavior of an Al-Zn-Mg-Cu Alloy during Non-Isothermal Creep Aging with Axial Tension Stress

Zhu

Jiang

et al. 2020

Metals

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Theprecipitate behavior, mechanical properties and corrosion behavior of an Al-Zn-Mg-Cu alloy during non-isothermal creep aging were investigated. The results show that diffraction patterns of GPI zones gradually disappear and those of η′ phases are strengthened during the heating stage. More importantly, the size and volume fraction of precipitates increase with aging temperature increasing, which greatly enhances the mechanical properties of the alloy. The hardness and tensile strength of the alloy with H210 aging condition are 165 HV and 564 MPa, respectively. During the cooling stage, in addition to the diffraction pattern of η′ phase, that of GPI zones can be observed again. Furthermore, the size of the precipitates decreases, and the volume fraction reaches a maximum. The hardness and tensile strength of the alloy with C120 aging condition reach 185 HV and 580 MPa, respectively. Furthermore, the characteristics of the grain boundary reveal that the width of precipitation free zones (PFZ) first increases during the heating stage and then decreases during the cooling stage. In the C120 condition, the newly generated secondary precipitates and the coarsening of undissolved precipitates around the grain boundary lead to the further narrowing of PFZ, but the coarse grain boundary precipitates (GBPs) are still not continuously distributed in the grain boundary. Hence, the alloy with C120 condition exhibits the most excellent corrosion resistance.

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Experimental and DFT characterization of η′ nano-phase and its interfaces in Al Zn Mg Cu alloys

Cited by 138 publications

References 57 publications

Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

Atomic-scale investigation of the interface precipitation in a TiB2 nanoparticles reinforced Al–Zn–Mg–Cu matrix composite

Modelling the Age-Hardening Precipitation by a Revised Langer and Schwartz Approach with Log-Normal Size Distribution

Precipitate Behavior, Mechanical Properties and Corrosion Behavior of an Al-Zn-Mg-Cu Alloy during Non-Isothermal Creep Aging with Axial Tension Stress

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