中文摘要：

本文研究了高频感应炉熔炼的Mg-Gd-Nd合金在200℃等温时效过程中晶界无析出带（PFZ）的形成和生长。通过透射电镜观察并结合能谱分析发现,晶界PFZ形成初期受空位损耗控制。随着时效时间的延长,晶界析出相粗化,晶界PFZ的宽度增加,PFZ的成长逐渐转变为受溶质损耗影响。当PFZ中稀土溶质原子浓度近似达到200℃合金中该元素的平衡含量时,PFZ宽度最终达到其极限值,约为275nm。

英文摘要：

The formation and growth of precipitate free zones （PFZ） along low-angle grain boundaries（GBs） have been investigated for the Mg96.9Gd2.8Nd0.3 alloy prepared by induction melting method and subsequent aging at 200 ℃. By means of TEM observations and nano- electron-probe EDS analysis, we found that the formation of a PFZ is mainly controlled by vacancy depletion along GBs at the earlier stage of aging. With increasing aging time, the equilibrium precipitates formed along GBs coarsens, and growth of PFZ turns to be affected by the process of solute depletion near GBs . The width of PFZ increases with the solute concentration inside PFZ decreasing. When the solute concentration within PFZ is close to the corresponding equilibrium concentration in the matrix at a defined aging temperature, the width of PFZ will reach its final value.