氟锆酸钾盐混合物对Mg-3Y-3.5Sm-2Zn合金组织和性能的影响

Effect of Potassium Fluorozirconate Salts Mixture on the Microstructure and Mechanical Properties of Mg-3Y-3.5Sm-2Zn Alloy

摘要:

制备了三种氟锆酸钾(K2ZrF6)盐混合物(M),分别在三个温度下将三种盐混合物加入到铸态Mg-3Y-3.5Sm-2Zn合金中。通过差热分析(DSC),X射线衍射(XRD),光学显微镜(OM),扫描电子显微镜(SEM),能量色散谱(EDS)和拉伸试验研究了合金的显微组织和力学性能,讨论了K2ZrF6盐混合物在合金中的晶粒细化机理。结果表明,铸态Mg-3Y-3.5Sm-2Zn合金由α-Mg,Mg12(Y,Sm)Zn 和 (Mg,Zn)3(Y,Sm)三种相组成。SEM和XRD检测发现,添加K2ZrF6盐混合物不会在合金中产生新的相。在780°C下加入M3盐(60wt% K2ZrF6-20wt% NaCl-20wt% KCl)时,合金的晶粒细化效果最佳。通过在780℃下加入三种盐,铸态Mg-3Y-3.5Sm-2Zn合金的力学性能得到提高,由M3盐细化后的合金具有最佳的力学性能。K2ZrF6盐混合物可细化铸态Mg-3Y-3.5Sm-2Zn合金,这是由于Mg和K2ZrF6之间还原反应得到的细Zr质点和富锆区在合金中起到的晶粒细化作用。

Abstract:

Three potassium fluorozirconate (K2ZrF6) salts mixture (M) were prepared and added to the as-cast Mg-3Y-3.5Sm-2Zn alloys at three different temperatures. The microstructures and mechanical properties of the alloys were investigated by differential thermal analysis (DSC), X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and tensile test. The grain refinement mechanism of K2ZrF6 salts mixture was also discussed. The results show that the as-cast Mg-3Y-3.5Sm-2Zn alloy is composed from three phases, namely α-Mg, Mg12(Y,Sm)Zn and (Mg,Zn)3(Y,Sm). The addition of K2ZrF6 salts mixture does not lead to the formation of any new phase detectable by SEM and XRD. M3 salt (60wt% K2ZrF6-20wt% NaCl-20wt% KCl) added at 780°C exhibits the best grain refining effect. The mechanical properties of the as-cast Mg-3Y-3.5Sm-2Zn alloy are improved by three salts added at 780°C, where the alloy refined by M3 salt has the best mechanical properties. The grain refinement mechanism of K2ZrF6 salts mixture in the as-cast Mg-3Y-3.5Sm-2Zn alloy is attributed to the grain refining effect of fine Zr particles and zirconium-rich zones obtained by the reduction reaction between Mg and K2ZrF6.