【摘要】 对7A99超高强铝合金反向挤压材采用T6峰值时效处理与冷热循环峰值时效热处理（简称T6-DCT）,通过TEM、HRTEM与3DAP研究深冷处理对峰值时效析出相的种类、分布、尺寸以及析出密度的影响。结果表明,冷热循环峰值时效处理后晶粒内部析出相种类增多,由η’相变成η’相与η相共存;冷热循环峰值时效处理可以将析出相的平均等效半径由1.201nm减小为1.001 nm,将析出相的密度由4.53×10²⁴/m³提升至7.55×10²⁴/m³,实现弥散强化;深冷处理可以降低Zn、Mg元素的微观偏聚,提高析出相的分布均匀性。更多还原

【Abstract】 Backward extrusion 7A99 ultrahigh-strength aluminium alloy was treated by T6 peak aging treatment and peak cold-heat cycle aging treatment（T6-DCT）. The influences of T6-DCT treatment on the types, distribution, size and density of the precipitated phases were investigated by TEM, HRTEM and 3DAP. The result shows that the types of the precipitated phases increase, i.e. η’ phase turn to η’ phase and η phase. The average equivalent radius of the precipitated phases changes from 1.201 nm to 1.001 nm after T6-DCT. The density of the precipitated phases increases from 4.53×10²⁴/m³ to 7.55×10²⁴/m³, which leads to dispersion-strengthening. After T6-DCT, the segregation of Zn and Mg decreases,and the precipitated phases distribute more homogeneously than those in the T6 treated sample.更多还原