机械合金化结合热压制备高硅铝合金的组织及性能

Microstructures and properties of high-silicon aluminum alloys fabricated by mechanical alloying and hot pressing

采用机械合金化结合热压的工艺制备Al-30Si、Al-40Si、Al-50Si三种成分的高硅铝合金,通过扫描电镜(SEM)、能谱分析仪(EDS)、X射线衍射仪(XRD)、密度及布式硬度测定仪等对机械合金化粉末的形貌及其演化,以及热压块体的组织与性能进行研究。结果表明:机械合金化8h的粉末细化效果较好,氧含量较低;合金的致密度随Si含量的增加逐渐降低;合金组织呈现Al相富集区和Si相富集区,Si颗粒粒径小于5μm,没有出现明显长大现象;Al2O3、SiO2等氧化物颗粒分布在铝硅界面和基体中;合金的布氏硬度随Si含量的增加先升高后降低;Al-40Si的硬度高达144 HB,比压力熔渗法制得的Al-40Si高50%。因此,机械合金化结合热压致密化的制备工艺可显著提高高硅铝合金的力学性能。

Three kinds of high-silicon aluminum alloys（Al-30Si,Al-40Si and Al-50Si） were fabricated by mechanical alloying and hot pressing.The morphology and morphological evolution of the as-milled high-silicon aluminum powders,the microstructures and properties of the compacts were investigated by scanning electron microscopy（SEM）,energy dispersive spectrometer（EDS）,X-ray diffractometer（XRD）,density and brinell hardness measurements.The reseach results show that the powders have a better control of powder properties and a lower content of extra oxygen after milled for 8h.The relative densities of the three alloys decrease with increasing the Si content.The alloys contain both Al-rich regions and Si-rich regions,the Si particals do not grow up obviously with a diameter of less than 5 μm.The oxides,such as Al2 O3 and SiO2,distribute in boundaries and matrix with a dispersion strengthening effect.The brinell hardness of the alloys increase at first and then decrease with increasing the Si content.The hardness of the Al-40Si reaches a value of 144HB which is 50% higher than that of the same alloy fabricated by pressure infiltration technology.And these results indicate that such a fabrication process can improve the mechanical properties of the high-silicon aluminum alloy significantly.