The Degradation of Microstructure of AlCu4Ni2Mg Aluminium Alloy after Prolonged Annealing at Elevated Temperature

Abstract:

The influence of long term annealing on microstructure of Al-Cu4-Ni2-Mg aluminum alloy was investigated. The castings were subjected to T6 heat treatment followed by annealing at 523 K and 623 K for 100, 150, 300, 500 and 750 hours. The soaking time and temperature was adjusted by corresponding to real service conditions of the elements of an aircraft and motor engines from investigated alloys. Microstructural examination of the alloy was carried out with optical microscope, as well as scaning and transmissiom electron microscopes. The result of microscopic analysis showed that applied heat treatment caused an increasing in the particles of hardening (θ’-Al2Cu) phase size. The significant growth of the length and changing the value of shape factor of hardening phase precipitations was observed. The phenomenon of the increase in size and change in shape of precipitations of hardening phases continually change with the prolonged holding time at high temperature. The microstructure degradation is connected to a decrease of mechanical properties of alloy, confirmed by the result of tensile tests.

• Periodical: Solid State Phenomena (Volume 186)
• Pages: 315-318
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.186.315
• Online since: March 2012
• Authors: Małgorzata Wierzbińska, Jan Sieniawski
• Keywords: Aluminium Alloy, Electron Microscope, Hardening Phase Precipitations, Microstructure Degradation, Microstructure Examination, Optical Microscope, Shape Factor

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DOI: 10.1111/j.1365-2818.2009.03316.x

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