Thermal stability and precipitate microstructures of Al−Si−Mg−Er alloy

Al−Si−Mg−Er合金的热稳定性和析出相的显微组织

The effect of Er on the microhardness and precipitation behavior of the heat-treated Al−Si−Mg alloy was investigated by microhardness tester and TEM.As a comparison,the influence of natural aging was also studied.It is shown that the thermal stability of the over-aged Al−Si−Mg−Er alloy is highly related to the average size of the precipitates.The average size ofβ''precipitates in Al−Si−Mg−Er alloy is smaller than that in Al−Si−Mg alloy,and the distribution is more localized under condition of without introducing natural aging.However,when natural aging is introduced before artificial aging,the Al−Si−Mg−Er alloy has similar average size and distribution of precipitates with the Al−Si−Mg alloy,resulting in similar mechanical properties.The effect of Er on the precipitation kinetics in the alloy was also discussed in detail to explain these phenomena.

采用显微硬度计和透射电镜研究Er元素对热处理Al−Si−Mg合金显微硬度和析出行为的影响。作为对照,同时研究人工时效前引入自然时效对合金硬度和析出行为的影响。研究结果表明,过时效Al−Si−Mg−Er合金的热稳定性与析出相的平均尺寸密切相关。未引入自然时效时,Al−Si−Mg−Er合金中β''相的平均尺寸小于Al−Si−Mg合金中β''相的平均尺寸,且其尺寸分布更加集中。然而,当在人工时效之前引入自然时效时,Al−Si−Mg−Er合金中析出相的平均尺寸和分布均与Al−Si−Mg合金的类似。此时,两种合金具有相似的力学性能。此外,详细讨论Er对合金中析出相析出动力学的影响,来解释上述现象。