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Málek, P.; Janeček, Miloš; Smola, Bohumil; Bartuška, P.; Pleštil, Josef

doi:10.1023/a:1004739718504

Cited by 34 publications

(11 citation statements)

References 11 publications

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“…The SEM micrographs of the assolidified specimens were obtained with an Hitachi S-3500 instrument (Hitachi High Technologies America, Inc., Pleasanton, CA) operated at an accelerating voltage of 20 kV, using a secondary electron detector. The as-cast alloys were isothermally aged at 375°C or 425°C, within the range of temperatures reported to exhibit a strong age hardening response for Al-Ti alloys produced by RSP [4,6,39,40] or MA [10] and for Al-Zr alloys produced by RSP [34,[41][42][43][44] or chill casting. [45,46] Precipitation of Al 3 Ti or Al 3 Zr during aging was monitored by a number of techniques, described subsequently.…”

Section: B Aging Treatments and Analytical Techniquesmentioning

confidence: 99%

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Knipling

Dunand

Seidman

2007

Metall Mater Trans A

178

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Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375°C or 425°C. This is due to the absence of Al 3 Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al 3 Zr (L1 2 ) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in a-Al is much greater than that of Zr in a-Al; and (2) the relatively small liquid solubility of Ti in a-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al 3 Ti (L1 2 ) with a-Al is also larger than that of Al 3 Zr (L1 2 ), further hindering nucleation of Al 3 Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al 3 Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al 3 Ti precipitation and the presence of Al 3 Zr precipitation.

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Section: B Aging Treatments and Analytical Techniquesmentioning

confidence: 99%

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Knipling

Dunand

Seidman

2007

Metall Mater Trans A

178

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“…Especially the microstructure refinement has been very popular during the last three decades and numerous entirely new processing routes have been developed. Some of them are based on rapid solidification (e.g., melt spinning and atomization) [1] and they produce generally materials far from the thermodynamic equilibrium state -supersaturated solid solutions [2], very fine grain size [3], etc. From the technological point of view, these methods are accompanied by a very important drawback -only a limited amount of material can be produced.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and deformation behaviour of the ECAP Al-Mn-Sc-Zr alloy

MALEK¹,

Cieslar²

2021

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The Al-Mn alloy stabilized by the addition of Sc and Zr was subjected to equal-channel angular pressing (ECAP) at room temperature. The microstructure evolution as a function of the number of ECAP passes was studied by transmission electron microscopy. The room temperature strength was characterized by microhardness measurements and tensile tests. The stability of the very fine-grained microstructure and strength characteristics were studied at elevated temperatures. Due to a good microstructure stability even after annealing at 500• C the possibility of superplastic behaviour was tested. The value of the strain rate sensitivity parameter m exceeding the bottom limit of superplastic behaviour was found.K e y w o r d s : Al-alloys, ECAP, microstructure, mechanical properties, superplasticity

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“…The microhardness of the powder material can be measured only in the largest powder particles containing numerous primary particles. Therefore, the microhardness value is much smaller than that of the melt-spun material of similar composition [9]. The inhomogeneity of the microstructure is also responsible for the high standard deviation of microhardness measurement on powder particles.…”

Section: Discussionmentioning

confidence: 98%

“…Such a microstructure cannot be achieved using chill casting as coarse primary particles are formed already during casting [6]. It has been shown previously that neither the high solidification rate in gas atomization or melt spinning process can result in a completely micro-segregation free microstructure [4,7]. However, the formation of coarse particles can be suppressed and a refined microstructure can be formed.…”

Section: Discussionmentioning

confidence: 99%

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High Temperature Stability of an Al-Zr-Ti Alloy Prepared using Gas Atomization and Spark Plasma Sintering Technology

et al. 2018

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The aim of this study was to prepare an aluminium alloy with high temperature stability using the powder metallurgical route. Gas atomized powder of the Al-Zr-Ti alloy was consolidated by the spark plasma sintering (SPS) technology. The fine grained structure (grain size between 2 and 3 µm) observed in the gas atomized powder was retained after sintering both at 425 • C and 550 • C. The microhardness of 49 HV observed in the gas atomized powder was increased up to about 100 HV in the SPS compacts. Precipitation of the Al3(Zr,Ti) phase during sintering can explain this strengthening. The materials stability was tested by annealing at temperatures above 450 • C. The grain size remained stable even after 10 h of annealing. A decrease in microhardness by about 20% can be attributed especially to the formation of the stable modification of the Al3(Zr,Ti) phase.

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Cited by 34 publications

References 11 publications

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Microstructure and deformation behaviour of the ECAP Al-Mn-Sc-Zr alloy

High Temperature Stability of an Al-Zr-Ti Alloy Prepared using Gas Atomization and Spark Plasma Sintering Technology

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