中國(guó)有色金屬學(xué)報(bào)(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 31 No. 11 November 2021 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Baotou Vocational & Technical College, Baotou 014030, China;
3. Key Laboratory of Non-ferrous Metals Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The quenching sensitivity of AA7136 alloy was investigated by time-temperature-property (TTP) diagrams, and the heterogeneous precipitation behavior during isothermal holding was investigated using scanning electron microscopy, scanning transmission electron microscopy and high resolution transmission electron microscopy. Based on 99.5% TTP diagram, the nose temperature is determined to be about 346 °C with the transformation time of about 0.245 s. The precipitation of η (MgZn2), T (Al2Zn3Mg3), S (Al2CuMg) or Cu-Zn-rich Y phases can be found depending on isothermal holding temperature and time, and it is described in a time-temperature-precipitation diagram. The size and area fraction of isothermal holding induced phase particles increase, which results in the decrease of hardness of samples after aging. The quantitative contribution to loss of hardness by grain boundaries/subgrain boundaries and dispersoids in the matrix is discussed based on the amount of heterogeneous precipitation related to them.
Key words: AA7136 alloy; quenching sensitivity; time-temperature-property diagrams; heterogeneous precipitation
