Abstract:The effects of aging temperature and aging time on the mechanical properties and electrical conductivity of 2A14 aluminum alloy were investigated by microhardness test, electrical conductivity test, tensile test and transmission electron microscopy (TEM). The results show that the electrical conductivity of the sample increases gradually with increasing temperature or aging time when the aging time or aging temperature are constant. The Al₁₂(MnCu)₃Si₂ particles found in the solid solution 2A14 alloy has a similar crystal structure with Al₆Mn, the Al₁₂(MnCu)₃Si₂ particles affect the migration of grain boundary during recrystalline process and restrain the grain growth during solid solution. For the 2A14 alloy, the S'''' phase is the mainly strengthening precipitates. However, for the sample aged at 140 ℃ (or lower than 140 ℃) for 12 h, the mechanical properties are close to the sample in solution-treated condition due to less strengthening phase. After aging at 160 ℃ for 12 h, the alloy shows better combination mechanical properties, the ultimate tensile strength (UTS), yield strength (YS) and elongation are 509 MPa, 452 MPa and 10.1%, respectively. After aging at 180 ℃ for 12 h, with the increase of aging temperature and extension of aging time, the precipitate size of S'''' phase increases and the mechanical properties decrease obviously, which is a typical phenomena of over aging.

Key words: 2A14 alloy; mechanical property; electrical conductivity; microstructure