Effect of three-step homogenization on microstructure and properties of 7N01 aluminum alloys
(1. National Engineering Research Center for High-Speed EMU, CRRC Qingdao Sifang Co., Ltd., Qingdao 266000, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China)
Abstract: The effect of different homogenization treatments on the microstructure and properties of the 7N01 aluminum alloy was investigated using hardness measurements, electrical conductivity measurements, tensile and slow strain rate tests, electron probe microanalysis, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results revealed that three-step homogenization improved the uniformity of Zr distribution by eliminating segregation of the main alloying elements. During the second homogenization step at 350 °C for 10 h, coarse and strip-like equilibrium η phases formed which assisted the nucleation of Al3Zr dispersoids and reduced the width of the precipitate-free zone of A13Zr dispersoids. As a result, coarse recrystallization was greatly reduced after homogenization at 200 °C, 2 h + 350 °C, 10 h + 470 °C, 12 h, which contributed to improving the overall properties of the 7N01 aluminum alloys.
Key words: 7N01 aluminum alloy; three-step homogenization; microstructure; mechanical properties; stress corrosion cracking