Si对Al-Mg-Cu合金时效析出行为的影响

Influence of Silicon on Aging Hardening Behavior of Al-Mg-Cu Alloy

向不同镁含量的Al-Mg-Cu合金中添加Si元素,研究Si对该合金时效强化行为的影响,并在此基础上探究自然时效处理对合金后续人工时效行为的影响。研究结果表明,在2.0%Mg的基础上添加0.15wt%Si可以显著增强合金的人工时效强化效果,但是合金强度随Si含量的进一步增加而增加的幅度较小;Si对合金的时效强化效果是由于Si使得合金中的时效析出相明显细化且分布弥散。添加0.15%Si的合金在经过自然时效后再进行人工时效(简称双时效),经双时效后的人工时效前期的硬度值高于直接人工时效的硬度值,但两种时效工艺峰值硬度基本相同;然后若继续增加Si含量,合金经双时效后的硬度峰值低于直接人工时效所得的硬度值。

Traces of silicon were added into Al-Mg-Cu alloy to study the effect of microalloyed silicon on aging precipitation after solid solution of the alloy as well as the effect of natural aging on subsequent artificial aging.It can be seen that the addition of traces of silicon(0.15 wt%)based on the certain mass of Mg(2.0 wt%)significantly enhances the strengthening effect of the alloy.With the further increasing content of silicon,the level of aging hardening is further improved,but not so significant.Precipitation can be greatly refined and more uniformly distributed.Besides,the density of the precipitation increases with the addition of silicon.After a long period of natural aging,the hardness value of the alloy with silicon(0.15 wt%)kept at the early stage of artificial aging is higher than that of the alloy with direct artificial aging,while both almost have the same peak hardness.With further increase of silicon content from 0.15 wt%,the peak hardness of artificial aging after natural aging process is lower than directly artificial aging.In conclusion,adding 0.15wt% Silicon has the best stengthening effect to the Al-Mg-Cu alloy,and enhancing the strength of the alloy to the greatest extent in the subsequent baking process.