固溶处理后镁铝合金时效峰值硬度时微观结构的电子显微分析

摘要

用显微维氏硬度计、金相显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究分析了Mg-10.33wt.％Al-1.26wt.％Zn合金固溶后的时效硬化规律.实验结果表明AZ91(Mg-9wt.％Al-1wt.％Zn-0.2wt.％Mn)合金添加少量的Al后固溶强化和时效强化效果均有显著提高.实验的时效硬度曲线表明:固溶处理后的Mg-10.33wt.％Al-1.26wt.％Zn合金在473K时效10 h获得最佳时效强化效果.经过分析,进一步证实Mg-10.33wt.％Al-1.26wt.％Zn合金固溶后时效过程中单位体积内的连续析出相γ-Mg17Al12相颗粒的数目(Nv)越大,样品的显微硬度值越高.%Age-hardening behavior of the Mg-10. 33wt. % Al-1. 26wt. % Zn alloy after solution treatment was observed and analyzed by a micro-Vikers hardness tester, X-ray diffraction ( XRD ) , optical microscopy ( OM ) , scanning electron microscopy ( SEM ) , and transmission electron microscopy (TEM). The results show that solid solution strengthening and age-hardening of the Mg-10. 33wt. % Al-1. 26wt. %Zn alloy are both greatly improved, compared with AZ91 ( Mg-9wl. % Al-lwt. % Zn-0. 2wt. % Mn) . The age-hardening curves show that aging at 473K for 10 h, the dissolution-treated Mg-10. 33wt. % Al-1. 26wt. % Zn alloy will reach its peak-hardness. The present results and analysis confirm that continuous precipitation plays an important role in improving ago-hardening effects in Mg-Al based alloys.