BENEFICIAL EFFECT OF HEAT TREATMENT ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF ALUMINUM ALLOYS USED IN AEROSPACE INDUSTRY

Commercially available aluminum - copper – magnesium alloys (Ly-12 and 2024-O) containing up to 4.5% copper and 1.5% magnesium has potential applications in aircraft and aero-space industry. These two alloys whose composition was close to the alloy actually used in aircraft structure were compared with reference to their mechanical properties and microstructure. Also comparison was made with selected conventional aluminum-base alloys, which are intended to be replaced by these alloys. Comparison of Ly-12 and 2024-O is made on the basis of their mechanical properties. Measured mechanical properties were found related to microstructures present in these alloys. Variation of microstructure was created by heat treatment of these alloys at different temperatures and by using different quenching media. Mechanical properties including Load at Break, Elongation at Break, Load at Peak, Stress at Peak, Young Modulus and Elongation at Yield were all measured using Universal Testing Machine. Hardness was measured with Brinell Hardness Tester. Electrical conductivity was also recorded for specimens. The mechanical test data gave information about their Yield Strength, Tensile Strength, Elongation, Ductility and hardness. Microstructures measured gave information of their grain size and were determined by using scanning electron microscope equipped with EDX.