Title of article :
MECHANISMS OFPRECIPITATES FORMATION IN AN Al- Cu- Li-ZrALLOYUSINGDSC TECHNIQUE AND ELECTRICALRESISTANCE MEASUREMENTS
Author/Authors :
Ahmadi, S. tarbiat modares university - Faculty of Engineering - Department of Material Science, تهران, ايران , Arabi, H. iran university of science and technology - School of Metallurgy and MaterialsEngineering - Center of Excellence of Advanced Materials and Processing (CEAMP), تهران, ايران , Nouri, S. iran university of science and technology - School of Metallurgy and Materials Engineering - Department of Industrial Engineering, تهران, ايران , Shokuhfar, A. k.n.toosi university of technology - Faculty of Mechanical Engineering - Department of Material Science, تهران, ايران
Abstract :
Abstract: Guinier-Preston (GP) zone formation and precipitation behavior of T1 (Al2CuLi) phase during the ageingof an Al-Cu-Li-Zr alloy was studied by differential scanning calorimetry (DSC) technique and electrical resistancemeasurement of the samples. Results show that endothermic effects in the thermograms of the alloy between 180°Cand 240°C can be related to the enthalpy of GPzones dissolution. Formation of GPzones in the structure increasedhardness, tensile strength and electrical resistance of the Al-Cu-Li-Zr alloy. Furthermore, precipitation of T1 phaseoccurred in temperature range of 250ºC to 300ºC whereas its dissolution occurred within the temperature of 450-530ºC. Activation energies for precipitation and dissolution of T1 phase which were determined for the first time inthis research, were 122.1(kJ/mol) and 130.3(kJ/mol) respectively. Results of electrical resistance measurementsshowed that an increase in the aging time resulted in the reduction of electrical resistance of the aged samples.
Keywords :
aluminum , lithium alloys, DSC , activation energy, natural aging, Al , Cu , Li , Zr alloy, T1 phase, dissolutionenergies
Journal title :
Iranian Journal of Materials Science and Engineering
Journal title :
Iranian Journal of Materials Science and Engineering
