论文部分内容阅读
采用原位电阻法、选区电子衍射(SADPs)、透射电镜(TEM)和力学性能测试研究一种Al-Zn-Mg-Cu合金从固溶温度经不同非线性冷却条件冷却至室温的组织性能演变规律,引入相对电阻的概念描述不同非线性冷却中的相变过程。结果表明:在高温条件下,随着冷却速率的降低,合金的显微组织演变由Zn、Mg原子的定向扩散转变为S相的析出。在中温区间内,在较快的冷却条件下,η相首先在Al_3Zr弥散粒子和晶界上形核,在较慢的冷却条件下,S相析出,异质形核产生的粗大第二相粒子会导致合金的力学性能恶化。在低温区间,GP区、η′和η相都有可能均匀地析出。
The properties of Al-Zn-Mg-Cu alloys from the solution temperature to the room temperature after cooling under different nonlinear cooling conditions were investigated by in-situ resistance, selective area electron diffraction (SADPs), transmission electron microscopy (TEM) and mechanical properties tests. The law introduces the concept of relative resistance to describe the phase transition in different nonlinear cooling. The results show that at high temperature, the microstructure evolution of the alloy changes from the directional diffusion of Zn and Mg atoms to the precipitation of S phase as the cooling rate decreases. In the mid-temperature range, under the faster cooling conditions, the η phase first nucleates on the Al 3 Zr dispersed particles and the grain boundaries. Under slower cooling conditions, the S phase precipitates and the coarse second phase particles generated by the heterogeneous nucleation Will lead to deterioration of the mechanical properties of the alloy. In the low temperature range, GP zone, η ’and η phase are likely to precipitate evenly.