微量Co对7085铝合金淬透性的影响

Effect of Trace Co on the Hardenability of 7085 Aluminum Alloy

通过末端淬火实验、硬度测试、常温力学性能测试、光学显微镜(OM)、扫描电镜(SEM)及透射电镜(TEM)等分析观察方法,研究了添加微量Co元素对7085铝合金淬透性的影响。结果表明:添加质量分数为0.1%的Co,降低了7085铝合金强度的淬火敏感性,提高了其淬透性,这与Co的添加抑制合金的再结晶,降低慢速冷却时粗大η平衡相的异质形核点数量有关。而添加过量的Co(0.4%)时,基体中产生大量粗大富Co难溶相,并起到一定的强化效果,但富Co相的存在,作为粒子激发形核的核心,促进了再结晶的发生,导致7085铝合金强度的淬火敏感性增大,淬透性降低。

The effect of trace cobalt on the hardenability of 7085 aluminum alloy was investigated by end-quench test, hardness test, ambient tensile test, optical microscopy （OM）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, The results show that 0.1% Co addition decreases the quench sensitivity for the strength and improves the hardenability of the alloy, because 0.1% Co addition inhibits the recrystallization, and thus decreases the number of heterogeneous nucleation points of coarse MgZn2（r/） equilibrium phase. However, excessive Co addition （0.4%） causes the formation of a large amount of coarse hard dissolved Co-rich phases, and gains the coarse particle reinforcement. But the existence of Co-rich phases serving as cores of the particle stimulates the nucleation and promotes the recrystallization of the alloy, which increases the quench sensitivity for the strength and decreases the hardenability of 7085 aluminum alloy.