Effects of Isothermal Heat Treatment on Microstructure of Mg-7Zn-1Cu-0.3Mn-xNd Alloy

Huang Xiaofeng; Yang Fan; Shang Wentao; Zhang Zhanyu; Zhang Sheng

doi:10.15980/j.tzzz.2022.06.008

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Effects of Isothermal Heat Treatment on Microstructure of Mg-7Zn-1Cu-0.3Mn-xNd Alloy
Vol. 42, Issue 6, Pages: 705-712(2022)
Published： 2022 ，
DOI： 10.15980/j.tzzz.2022.06.008

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Huang Xiaofeng, Yang Fan, Shang Wentao, et al. Effects of Isothermal Heat Treatment on Microstructure of Mg-7Zn-1Cu-0.3Mn-xNd Alloy. [J]. Special Casting & Nonferrous Alloys 42(6):705-712(2022)
DOI：

Huang Xiaofeng, Yang Fan, Shang Wentao, et al. Effects of Isothermal Heat Treatment on Microstructure of Mg-7Zn-1Cu-0.3Mn-xNd Alloy. [J]. Special Casting & Nonferrous Alloys 42(6):705-712(2022) DOI： 10.15980/j.tzzz.2022.06.008.

摘要

设计了Mg-7Zn-1Cu-0.3Mn-xNd（x=0

0.1

0.3

0.5

质量分数，%）镁合金，利用OM、XRD以及SEM等观察了不同Nd添加量时合金的铸态组织以及经过等温热处理后的半固态非枝晶组织演变，探索了Mg-7Zn-1Cu-0.3Mn-0.3Nd合金的最佳等温热处理工艺。结果表明，Mg-7Zn-1Cu-0.3Mn-xNd合金的铸态组织主要由α-Mg、Mg

、NdCu

和CuMgZn相组成，加入0.3%的Nd对晶粒具有最好的细化效果，共晶组织分布更加弥散；Mg-7Zn-1Cu-0.3Mn-0.3Nd合金在595℃下保温30 min后可获得最理想的半固态非枝晶组织，其固相率、固相颗粒的形状因子和平均晶粒尺寸分别为57.59%、1.38和44.56μm。非枝晶组织的演变由4个阶段构成，分别为初始的粗化阶段、组织分离、球化以及最后的粗化。

Abstract

Mg-7 Zn-1 Cu-0.3 Mn-xNd（x=0

0.1

0.3

0.5

%） magnesium alloys were designed. The as-cast microstructure of the alloys with different Nd contents and the evolution of semi-solid non-dendritic microstructure after isothermal heat treatment were observed by OM

XRD and SEM. The isothermal heat treatment process of Mg-7 Zn-1 Cu-0.3 Mn-0.3 Nd alloy was investigated and the evolution of semi-solid non-dendritic microstructure was analyzed. The results show that the as-cast microstructure of Mg-7 Zn-1 Cu-0.3 Mn-xNd alloy is mainly composed of α-Mg

NdCu

and CuMgZn phases. The desirable addition of Nd is 0.3%

where the satisfied grain refinement effect can be obtianed

and the eutectic microstructure is more dispersed. The optimal semi-solid non-dendritic microstructure of Mg-7 Zn-1 Cu-0.3 Mn-0.3 Nd alloy can be obtained after holding at 595 ℃ for 30 min. The solid fraction

shape factor and average particle size reach 57.59%

1.38 and 44.56 μm

respectively. The evolution of non-dendritic microstructure consists of the initial coarsening

structure separation

spheroidization

and final coarsening.