Precipitation kinetic of Al3(Sc,Zr) dispersoids in aluminium

Lefebvre, W.; Danoix, F.; Hallem, Håkon; Forbord, Børge; Bostel, A.; Marthinsen, Knut

doi:10.1016/j.jallcom.2008.02.043

Cited by 140 publications

(58 citation statements)

References 11 publications

(22 reference statements)

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“…in Refs. [9,10,15,20]). First, Zr segregates at the heterophase interface of the Al 3 Sc particles, afterwards the development of these particles with the L1 2 structure leads to the formation of the Al 3 (Sc,Zr) phase.…”

Section: Resultsmentioning

confidence: 99%

“…Positive eects on microhardness, recrystallization temperature, corrosion resistance and weldability attained due to the coherent spherical nanosized Al 3 (Sc,Zr) particles with the cubic L1 2 structure are very pronounced [15,8]. The decomposition sequence of the supersaturated solid solution of the AlScZr-based system is known in the following form [5,9,10]: Sc-rich clusters → Al 3 Sc phase → layer rich in Zr → Al 3 (Sc,Zr) phase.…”

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confidence: 99%

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Microstructure, Thermal and Mechanical Properties of Non-Isothermally Annealed Al-Sc-Zr and Al-Mn-Sc-Zr Alloys Prepared by Powder Metallurgy

et al. 2012

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This paper reports results of a study aimed at understanding the precipitation processes occurring during the annealing of two AlScZr-based alloys with and without Mn prepared by powder metallurgy with subsequent hot extrusion at 350• C. Samples were isochronally annealed up to ≈ 570 • C. Precipitation behaviour was studied by electrical resistometry and dierential scanning calorimetry. Mechanical properties were monitored by microhardness HV1 measurements. Transmission electron microscopy examinations and X-ray diraction of specimens quenched from temperatures of signicant resistivity changes helped to identify the microstructural processes responsible for these changes. Fine (sub)grain structure develops and ne coherent Al3Sc and/or Al3(Sc,Zr) particles precipitate during extrusion in both alloys. The distinct changes in resistivity (at temperatures above ≈ 330• C) of the AlMnScZr alloy are mainly caused by precipitation of Mn-containing particles. The easier diusion of Mn atoms along the (sub)grain boundaries is responsible for the precipitation of the Al6Mn and/or Al6(Mn,Fe) particles at relatively lower temperatures compared to the temperature range of precipitation of these particles in the classical mould-cast AlMnScZr alloys The apparent activation energy for precipitation of the Al3Sc and Al6Mn particles in the AlMnScZr alloy was determined as (106 ± 10) kJ mol −1 and (152 ± 33) kJ mol −1 , respectively.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Microstructure, Thermal and Mechanical Properties of Non-Isothermally Annealed Al-Sc-Zr and Al-Mn-Sc-Zr Alloys Prepared by Powder Metallurgy

et al. 2012

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“…During further annealing [~673 K (400°C)] dispersoids with complex core-shell structure consisting of an Al 3 Sc core embedded in an Al 3 (Sc,Zr) shell are developed. [4,5,14,15] Authors of the present study have already provided resistivity measurements of the Al-Sc-Zr alloy which showed that Zr-segregation to the Al 3 Sc/a-Al matrix interfaces might take place already at 573 K (300°C). [17] Electrical resistivity measurement is a convenient way to follow precipitation kinetics in phase-separating systems [18,19] as electrical resistivity having its origin in the scattering of free electrons by phonons and lattice defects reflects the material phase composition very sensitively.…”

Section: Introductionmentioning

confidence: 60%

“…[12,13] Atom-probe tomography (APT) was also employed to measure Sc,Zr concentration and distribution. [14][15][16] APT has shown that Sc-rich clusters can be formed in the early stages of precipitation above annealing temperatures of~523 K (250°C). [15] These clusters subsequently transform into the Al 3 Sc particles with the L1 2 structure.…”

Section: Introductionmentioning

confidence: 99%

“…[14][15][16] APT has shown that Sc-rich clusters can be formed in the early stages of precipitation above annealing temperatures of~523 K (250°C). [15] These clusters subsequently transform into the Al 3 Sc particles with the L1 2 structure. When Zr diffusion becomes significant, Zr atoms are found to segregate to Al 3 Sc/aAl matrix interfaces.…”

Section: Introductionmentioning

confidence: 99%

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Early Stages of Precipitation Process in Al-(Mn-)Sc-Zr Alloy Characterized by Positron Annihilation

Vlach

Čı́žek

Melikhova

et al. 2015

Metall Mater Trans A

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Thermal effects on the precipitation stages in as-cast Al-0.70 at. pct Mn-0.15 at. pct Sc-0.05 at. pct Zr alloy were studied. The role of lattice defects was elucidated by positron annihilation spectroscopy (lifetime and coincidence Doppler broadening) enabling investigation of solutes clustering at the atomic scale. This technique has never been used in the Al-Sc-and/or Al-Zr-based alloys so far. Studies by positron annihilation were combined with resistometry, hardness measurements, and microstructure observations. Positrons trapped at defects are preferentially annihilated by Sc electrons. Lifetime of trapped positrons indicates that Sc atoms segregate at dislocations. Maximum fraction of positrons annihilated by Sc electrons occurring at 453 K (180°C) suggests that clustering of Sc bound with vacancies takes place. It is followed by peak of this fraction at 573 K (300°C). A rise of the contribution of trapped positrons annihilated by Zr electrons starting at 513 K (240°C) and attaining maximum also at 573 K (300°C) confirms that Zr participates in precipitation of the Al 3 Sc particles already at these temperatures. The pronounced hardening at 573 K (300°C) has its nature in the precipitation of the Al 3 Sc particles with a Zr-rich shell. The contribution of trapped positrons annihilated by Mn electrons was found to be negligible.

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The Effect of Transition Elements on High‐Temperature Mechanical Properties of Al–Si Foundry Alloys–A Review

2016

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The high temperature mechanical performance of Al-Si alloys can be enhanced by alloying with transition metals, induced by the formation of thermally stable and coarsening resistant precipitates in the microstructure. However, the binary dispersoids such as Al 3 Zr can be less effective due to limitations encountered during conventional manufacturing processes. Further improvements can be achieved through the transformation of these binary trialuminides into ternary or quaternary forms by alloying with appropriate elements. The role of transition elements in improving high temperature mechanical properties of Al-Si alloys from both theoretical and practical viewpoints is critically reviewed.

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Precipitation kinetic of Al3(Sc,Zr) dispersoids in aluminium

Cited by 140 publications

References 11 publications

Microstructure, Thermal and Mechanical Properties of Non-Isothermally Annealed Al-Sc-Zr and Al-Mn-Sc-Zr Alloys Prepared by Powder Metallurgy

Microstructure, Thermal and Mechanical Properties of Non-Isothermally Annealed Al-Sc-Zr and Al-Mn-Sc-Zr Alloys Prepared by Powder Metallurgy

Early Stages of Precipitation Process in Al-(Mn-)Sc-Zr Alloy Characterized by Positron Annihilation

The Effect of Transition Elements on High‐Temperature Mechanical Properties of Al–Si Foundry Alloys–A Review

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