Mg-Zn合金时效过程中GP区析出的热力学分析

来源期刊：金属学报2010年第5期

论文作者：王晓亮 李长荣 郭翠萍 杜振民 何维

文章页码：575 - 580

关键词：Mg-Zn合金； 低温时效； GP区； 热力学分析

Key words：Mg-Zn alloy； low temperature ageing； GP zone； thermodynamic analysis

摘    要：利用显微硬度、XRD及TEM分析了Mg-1.9Zn(原子分数,%)二元合金时效硬化现象及GP区的形态和出现的温度范围.研究结果表明:在343和383 K时效过程中,过饱和固溶体中发生Zn原子偏聚,形成形态不同的GP区;在423 K时效,硬化峰值出现较早,没有典型GP区出现.利用本文优化获取的镁基固溶体相的热力学参数,给出镁基过饱和固溶体存在亚稳态溶解度间隙和溶质原子偏聚GP区时Gibbs自由能曲线的特征形式,确定了具有GP区析出效应的Mg-Zn体系的合金成分范围和时效温度区间.

Abstract: The age-hardening behavior of the Mg-1.9Zn(atomic fraction,%) alloy,morphologies of GP zones and temperature range of GP zone precipitation in the alloy were investigated by microhardness, XRD and TEM.The results show that the Zn atoms segregation occurs in the supersaturated solid solution,forming GP zones with different shapes during ageing process at 343 and 383 K;while at 423 K the age-hardening peak occurs earlier but no typical GP zone appeared.Using the thermodynamic parameters of the Mg-Zn system,the Gibbs free energy relations of the Mg-based solid solution phase were calculated,indicating the existences of the metastable miscibility gap and the solute atoms segregation in the super-saturated solid solution.With the reported data and the present experimental results,the ranges of composition and aging temperature for GP zone precipitation in the Mg-Zn alloy were determined.