Annealing of vacancies and ageing in Al-Li alloys

Ceresara, S.; Giarda, A.; Sánchez, Ariany Colás

doi:10.1080/14786437708235975

Cited by 115 publications

(29 citation statements)

References 10 publications

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“…[36,41] The formation of Li-bearing zones [10,40] is attributed to the fact that, upon quenching the alloys from the solution treatment temperature, excess vacancies are quenchedin; this is because the Li-vacancy binding energy is high in the Al-Li and in the ternary Al-Li-Zn system. [42] Noble et al [30] believed it was caused by dissolution of subcritical L1 2 ordered regions. Sato et al [43] invoked a similar interpretation to explain the observed lowtemperature endotherm in their DSC studies of asquenched Al-Li alloys.…”

Section: Peak F Dissolution Of Li-bearing Zonesmentioning

confidence: 98%

Kinetics of Solid-State Reactions in Al-Li-Cu-Mg-Zr Alloys from Calorimetric Studies

Ghosh

Das

Chatterjee

2007

Metall Mater Trans A

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Differential scanning calorimetric (DSC) studies at different heating rates have been carried out to examine the solid-state reactions in 1441 and 8090 Al-Li-Cu-Mg-Zr alloys of water-quenched (WQ) and retrogressed tempers. The DSC peaks indicating the reactions sequence such as formation of GPB zones, precipitations of d¢ phase, dissolution of GPB zones and d¢ precipitates, and precipitations of S¢, T 1 , T 2 , and d phases have been identified. From the heat flow associated with the peaks of the thermograms, the fraction transformation (Y), the rate of transformation (dY/dt), the activation energy (Q*), the frequency factor (k 0 ), and the transformation function f(Y) for all the reactions of the 1441 and 8090 alloys have been determined. The appearance of separate peaks of GPB zone formation and d¢ precipitation in the 1441 alloy of retrogressed tempers has enabled determination of the kinetic parameters, which is otherwise not possible from the thermograms of the WQ state due to peak overlapping, by varying heating rate method. The kinetic parameters determined from the DSC data of all the reactions of the alloys are in good agreement with the previously published data.

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Section: Peak F Dissolution Of Li-bearing Zonesmentioning

confidence: 98%

Kinetics of Solid-State Reactions in Al-Li-Cu-Mg-Zr Alloys from Calorimetric Studies

Ghosh

Das

Chatterjee

2007

Metall Mater Trans A

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“…Decrease in resistivity due to annihilation of quenched-in vacancies in Al-Ni dilute alloys was reported as about 0.04-0.05 nm by the present authors, 11) and as about 0.04 nm in pure aluminum. 14 Figs. 4 and 5.…”

Section: Resistivity Changementioning

confidence: 99%

Precipitation in an Al-300 ppm Fe Alloy

2004

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Precipitation in deformed and undeformed Al-300 ppm Fe alloy has been investigated by means of resistivity measurements and transmission electron microscopy. The undeformed specimens were solution-heat-treated at 913 K for 3.6 ks, quenched in iced water and then aged at the temperatures between 393 and 848 K, while the deformed specimens were cold-drawn for resistivity measurement or cold-rolled for TEM observations after the same solution heat treatment, and then aged. Resistivity in the undeformed specimens decreased in two stages, while in the deformed specimens, resistivity decreased in two or three stages depending on aging temperatures. Time-Temperature-Precipitation (TTP) diagram for the undeformed specimens consisted of one C-curve which corresponded to precipitation of stable Al 3 Fe. The TTP diagram for the 65% cold-drawn specimens was separated into two C-curves: the curves in high and low temperature ranges corresponded to precipitation of Al 3 Fe and Al 6 Fe, respectively. The precipitation of metastable Al 6 Fe was observed only in the cold-rolled specimens. Acceleration effects of cold drawing on Al 3 Fe precipitation were hardly recognized.

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“…Accordingly, the present observed recovery processes in the temperature range 25--450 ~ might be ascribed to the growth of coherent Guinier-Preston zones formed at relatively lower temperatures [9] and the precipitation of the ~-phase (Al-Li) in the temperature range 200--300 ~ [1]. Since no precipitate except (Al-Li) exists, the dissolution of ~-phase takes place in the temperature range 300--450 ~ [1].…”

Section: Discussionmentioning

confidence: 99%

The role of lithium atoms in the structural changes in Al−Li alloy

et al. 1979

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The dependence of structural changes in preeipitating Al-10 at% Li alloy on the annealing temperatures as traeed by X-rays, eleetrie resistivity and mierohardness measurements revealed the formation and subsequent dissolution of Al-Li preeipitates in the temperature range of 25--500 ~ The observed variations were attributed to the effect of the annealing temperature on the behaviour of Li atoms within the Al matrix. The inerease of the Li concentration in the matrix due to the dissolution of Al-Li precipitates, being 3.75 at ~/o Li as obtained from X-ray measurements agreed well with the value 4.0 at % Li obtained from resistivity measurements. I n t r o d u c t i o n I t has been reported [1] t h a t in supersaturatedAl-Li alloys, the fl-phase (Al-Li) preeipitated b y annealing in the t e m p e r a t u r e range of 150--300 oC and dissolved at higher t e m p e r a t u r e s leads to the dispersion of the exeess Li atoms b y diffusion t h r o u g h the matrix. Sueh struetural ehanges affeeted largely b o t h the eleetrieal [2] and meehanieal [1] properties of the alloy.The present work airas at traeing the role of Li a t o m s in the Al m a t r i x in the struetural ehanges of different t e m p e r a t u r e s in the alloy from X -r a y diffraetion tests. Also, it is aimed at relating the variations in eleetrie resist i v i t y and mierohardness to these struetural ehanges. ExperimentalSamples of Al-10 at Yo Li were produced b y a m e t h o d previously deseribed [3]. Quenehing from 560 ~ to room t e m p e r a t u r e with a rate of 3 • 103 ~ was earried out to bring the samples in a m e t a s t a b l e s t a n d a r d eondition of solid solution. Isoehronal annealings were done b y heat pulses of 10 min at t e m p e r a t u r e s sueeessively increasing in steps of 20 ~ After eaeh heat pulse the resistanee of the samples was measured at room t e m p e r a t u r e using a standard potentiometrie m e t h o d [4]. A d u m m y sample helped to aeeount for the effeet of t e m p e r a t u r e variation. Microhardness m e a s u r e m e n t s I~ Acta Physica -,4cademiae Scientiarum Hungaricae 46, 1979

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Annealing of vacancies and ageing in Al-Li alloys

Cited by 115 publications

References 10 publications

Kinetics of Solid-State Reactions in Al-Li-Cu-Mg-Zr Alloys from Calorimetric Studies

Kinetics of Solid-State Reactions in Al-Li-Cu-Mg-Zr Alloys from Calorimetric Studies

Precipitation in an Al-300 ppm Fe Alloy

The role of lithium atoms in the structural changes in Al−Li alloy

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