Effect of Zr addition on microstructure of hot extruded P/M Al-Zn-Mg-Cu alloys

大樹, 足立; 光造, 長村; 拓也, 棚橋; 健, 菊地; 潤, 楠井

doi:10.2464/jilm.55.164

Cited by 7 publications

(11 citation statements)

References 9 publications

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“…Formation mechanisms of fine grains by continuous DRX are reported as follows. 8,12,13) Inhomogeneous local strains are induced by grain boundary shearing near grain boundaries of the initial coarse grain, and the local dislocation density increases. The dislocations are rearranged and a subboundary is formed.…”

Section: Resultsmentioning

confidence: 99%

“…8) Microstructural observation using high-resolution EBSP analysis revealed that this increase was due to the addition of Zr, which promoted continuous dynamic recrystallization (DRX) under hot extrusion and thus the formation of a large number of fine grains. 8) This is believed to be the effect of Al 3 Zr particles, which precipitated during the degassing treatment involving Zr addition. However, it is not clear why the presence of Al 3 Zr particles promotes continuous DRX under hot extrusion.…”

Section: Introductionmentioning

confidence: 99%

“…The tensile strength and elongation of this alloy are 785 MPa and 8.7%, respectively. 8) Extruding atomized powder containing 1.33 mass% Zr dissolved in the matrix (which exceeds the solid solubility limit of Zr in Meso10) was found to result in an increase in strength. 8) Microstructural observation using high-resolution EBSP analysis revealed that this increase was due to the addition of Zr, which promoted continuous dynamic recrystallization (DRX) under hot extrusion and thus the formation of a large number of fine grains.…”

Section: Introductionmentioning

confidence: 99%

“…8) Extruding atomized powder containing 1.33 mass% Zr dissolved in the matrix (which exceeds the solid solubility limit of Zr in Meso10) was found to result in an increase in strength. 8) Microstructural observation using high-resolution EBSP analysis revealed that this increase was due to the addition of Zr, which promoted continuous dynamic recrystallization (DRX) under hot extrusion and thus the formation of a large number of fine grains. 8) This is believed to be the effect of Al 3 Zr particles, which precipitated during the degassing treatment involving Zr addition.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

et al. 2005

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The presence of Al 3 Zr precipitates promotes continuous dynamic recrystallization in Al-Zn-Mg alloys during hot extrusion, resulting in a fine-grained structure. The mechanism for this phenomenon was investigated by observing the change in microstructure under hot extrusion using high resolution EBSP. In the rear of the extrusion die mouth, grain boundary mobility is low since the flow stress is comparatively low and grain boundary migration is inhibited by Al 3 Zr particles. Thus, in order to reduce the deformation-induced high dislocation density, continuous dynamic recrystallization occurs, which does not involve long-range grain boundary migration, resulting in a finer-grained structure. The flow stress, and hence, the mobility of the grain boundary increase near the die mouth. This promotes long-range grain boundary migration, which reduces the dislocation density. Continuous dynamic recrystallization is not observed under these conditions. Since Al 3 Zr precipitates inhibit long-range grain boundary migration, increase of the Al 3 Zr precipitate content expands the region where continuous dynamic recrystallization occurs towards the die mouth, resulting in a finer-grained structure.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

et al. 2005

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“…Zr addition to Meso10 in supersaturation leads to continuous dynamic recrystallization (DRX) occurs during hot extrusion, and many fine grains with diameters of about 1 mm are formed [2]. It is thought that L1 2 -structured Al 3 Zr particles precipitate upon the addition of 1.3 mass% Zr during the degassing process before hot extrusion, and that these particles inhibit the migration of initial grains [3,4].…”

Section: Introductionmentioning

confidence: 99%

Effect of dispersed Al3Sc particles on dynamic recrystallization in P/M 7000 series alloys

Adachi

Yammoto

Nakanishi

et al. 2009

Trans Indian Inst Met

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Al 3 Sc particles are well known to be a recrystallization inhibitor in Al alloys. In this study, 0.4, 0.8 and 1.5 mass% Sc were added to 7000 series Al alloys in supersaturation by using powder metallurgy. By subjecting rapidly solidified powders of these alloys to a heat treatment at 773 K, Al 3 Sc particles were precipitated in the matrix. Subsequently, hot extrusion was carried out at 773 K. During extrusion, continuous dynamic recrystallization (DRX) occurred and fine DRX grains with a diameter of 1 mm were formed. The number of DRX grains was the largest in the 1.5Sc alloy. Even though the amount of Sc added in this case was two times larger, the number of DRX grains in 0.4Sc was almost the same as that in 0.8Sc. Since continuous DRX occurs only under conditions where the grain boundary mobility is low, the number of DRX grains is strongly related to the pinning force on the initial grain boundary exerted by Al 3 Sc particles. The pinning force varied with the diameter and volume fraction of Al 3 Sc particles. When the pinning force was calculated from the diameter of Al 3 Sc particles, which was measured by TEM, it was proven that the number of DRX grains was proportional to the calculated pinning force. Except in the case of 0.4Sc, the Al 3 Sc particle diameter was twice that obtained at the maximum pinning force (d max ). It is possible to promote continuous DRX by decreasing the Al 3 Sc particle diameter in 0.8 and 1.5Sc alloys. Lowering the heating rate before heat treatment for degassing reduced the critical nucleus size for precipitation of Al 3 Sc particles as well the diameter of Al 3 Sc particles. Thus, the pinning force increased in 0.8Sc and 1.5Sc alloys, and the number of DRX grains also increased, as expected.

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Microstructure and mechanical properties of ternary intermetallic compound dispersed P/M Al-Mn-X-Zr (x=Cu,Ni) alloys

Adachi

Itaka

Aida

et al. 2009

Trans Indian Inst Met

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Heat-resistant aluminum alloys are generally developed by dispersing stable intermetallic compounds by adding transition metals (TM) whose diffusion coefficient in aluminum alloys is low even at high temperatures. Commonly used intermetallic compounds include Al-TM binary intermetallic compounds, for example, Al 6 Fe, Al 3 Ti and Al 3 Ni. By contrast, multicomponent intermetallic compounds are hardly used. The present study focuses on Al-Mn-Cu and Al-Mn-Ni ternary intermetallic compounds, and by finely dispersing these intermetallic compounds, attempts to develop heat-resistant alloys. Through the atomization method, Al-(4.96-5.96)Mn-(6.82-7.53)Cu-0.4Zr and Al-(5.48-8.76)Mn-(2.23-4.32)Ni-0.4Zr (in mass%) powders were fabricated, and by degassing these powders at 773 K, intermetallic compounds were precipitated. These powders were then solidified into extrudates by hot extrusion at 773 K. The microstructural characterization of powders and exrudates was carried out by XRD analysis, SEM/EDX and TEM. The mechanical properties of extrudates were determined at room temperature, 523 K and 573 K. In Al-Mn-Cu alloys, while a small amount of Al 2 Cu was crystallized, precipitated Al 20 Mn 3 Cu 2 intermetallic compounds were mainly dispersed. In Al-Mn-Ni alloys, while a small amount of Al 6 Mn intermetallic compounds was precipitated, the precipitated A 60 Mn 11 Ni 4 intermetallic compounds were mainly dispersed. Both ternary intermetallic compounds were about 200 nm in size. The compounds were elliptical, and their longitudinal direction was oriented along the extrusion direction. In the Al-Mn-Cu alloys, since the work hardening at room temperature was high, the tensile strength became 569 MPa. At elevated temperatures, since hardly any work hardening was observed, the tensile strength decreased markedly. However, in Al-Mn-Ni alloys, since the work hardening is low even at room temperature, the roomtemperature strength is not high. Thus, the decrease in tensile strength at elevated temperatures is relatively small and a high strength was obtained at 523 K and 573 K: 276 MPa and 207 MPa, respectively.

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Effect of Zr addition on microstructure of hot extruded P/M Al-Zn-Mg-Cu alloys

Cited by 7 publications

References 9 publications

Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

Effect of Zr Addition on Dynamic Recrystallization during Hot Extrusion in Al Alloys

Effect of dispersed Al3Sc particles on dynamic recrystallization in P/M 7000 series alloys

Microstructure and mechanical properties of ternary intermetallic compound dispersed P/M Al-Mn-X-Zr (x=Cu,Ni) alloys

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