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Ageing Kinetics of Al.-4.7 % Cu Alloy. Dilatometric and DTA Studies

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Abstract:

Studies of transformation kinetics during ageing of Al-4.7 % Cu were performed with use of dilatometric and DTA methods. The dilatometric method was used for studies of isothermal ageing, DTA for studies of ageing during isochronal heating. In order to determine isothermal transformation kinetics the JMA (Johnson – Mehl – Avrami) equation was applied, for isochronal heating transformation kinetics Kissinger method was used. Ageing of Al- Cu alloys consist of precipitation processes and dissolution processes that overlap each other. These processes, during isothermal ageing were distinguished with help of the time exponent n of JMA equation that is very sensitive to change of the transformation mechanism. During isochronal ageing, precipitation processes produce heat, dissolution processes consume heat. That helps to distinguish them. Results obtained during isothermal studies were in agreement with isochronal heating studies. Activation energies for precipitation processes 324-530 K temperature range varied from about 50 kJ/mol to about 100 kJ/mole and complied with the values obtained before. For precipitation processes at 650- 735 K temperature range, activation energies varied from 226 to 300 kJ/mole. The results obtained were discussed with literature data.

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Periodical:

Defect and Diffusion Forum (Volumes 237-240)

Pages:

768-773

DOI:

https://doi.org/10.4028/www.scientific.net/DDF.237-240.768

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Online since:

April 2005

Authors:

Ignacy Wierszyłłowski, Sebastian Wieczorek

Keywords:

Activation Energy, Aging Treatment (AT), Dissolution, G-P Zones, Isothermal Transformation, JMA Equation, Kissinger Method, Precipitation, Supersaturation, Time Exponent N, Transformation Kinetics

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© 2005 Trans Tech Publications Ltd. All Rights Reserved

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References

[1] D. Altenpohl: Aluminium und Aluminiumlegirungen . ( Berlin Springer Verlag 1965).

Google Scholar

[2] D.A. Porter, K.E. Easterling: Phase transformations in metals and alloys (Van Nostrand Reinhold Company 1981 New York).

Google Scholar

[3] J.W. Christian : The theory of transformations in metals and alloys ( 2-nd . Ed. London , Pergamon Press 1975).

Google Scholar

[4] P. Nowak: Badania procesów starzenia stopów Al-5%Cu . Próba symulacji komputerowej (Praca dyplomowa. Politechnika Poznańska WBMiZ 2002).

Google Scholar

[5] D. S. Thomson: The calorimetric observation of solid state reactions in aluminum alloys" (in Thermal analysis ASM 1970 1147-1170 ).

DOI: 10.1016/b978-0-12-395734-4.50037-0

Google Scholar

[6] G. W. Smith: Thermochimica Acta 317 (1998) 7-23.

Google Scholar

[7] G. W. Smith. Thermochimica Acta 313 (1998) 27-36.

Google Scholar

[8] D. Schultze: Termiczna analiza różnicowa (PWN Warszawa 1974).

Google Scholar

[9] W.N. Wendland: Thermal methods of analysis (New York , 1974).

Google Scholar

[10] E.J. Mittemeijer: Annual Report, Delft University of Technology 1990 (6-10).

Google Scholar

[11] I.A. Wierszyłłowski : Metallurgical Transactions 22A(1991) 993-999.

Google Scholar

[12] L. Lochte, A. Gitt, G. Gottstein and I. Hurtado , Acta Materialia 48 (2000) 2969-2984.

Google Scholar