摘要
The influence of trace Y on the microstructure evolution and mechanical properties of Mg_(100−x)Y_(x)(x=0.25,_(0.75),1.5,3,4,5,at.%)alloys during solidification process was investigated via molecular dynamics(MD)simulations.The results show that the Mg_(100−x)Y_(x) alloys are mainly characterized by a face-centered cubic(FCC)crystal structure;this is different from pure metal Mg,which exhibits a hexagonal close packed(HCP)structure at room temperature.Among these alloys,Mg_(99.25)Y_(0.75) has a larger proportion of FCC cluster structures,with the highest fraction reaching 56.65%.As the content of the Y increases up to 5 at.%(Mg95Y5 alloy),the amount of amorphous structures increases.The mechanical properties of the Mg_(100−x)Y_(x) alloys are closely related to their microstructures.The Mg_(99.25)Y_(0.75) and Mg_(97)Y_(3) alloys exhibit the highest yield strengths of 1.86 and 1.90 GPa,respectively.The deformation mechanism of the Mg−Y alloys is described at the atomic level,and it is found that a difference in the FCC proportion caused by different Y contents leads to distinct deformation mechanisms.
采用分子动力学(MD)模拟方法研究微量Y添加对Mg_(100−x)Y_(x)(x=0.25、_(0.75)、1.5、3、4、5,摩尔分数,%)合金凝固过程中显微组织和力学性能的影响。结果表明:Mg_(100−x)Y_(x)合金在室温下主要形成与单质Mg的HCP结构所不同的FCC晶体结构;Mg_(99.25)Y_(0.75)合金具有较多的FCC团簇结构,含量最高可达56.65%。当Y原子的含量增加到5%(摩尔分数)时,在Mg95Y5合金中形成更多的非晶结构。Mg_(100−x)Y_(x)合金的力学性能与其显微组织密切相关,Mg_(99.25)Y_(0.75)和Mg_(97)Y_(3)合金具有最高的屈服强度,分别为1.86 GPa和1.90 GPa。从原子水平分析Mg_(100−x)Y_(x)合金变形的机理,发现不同Y含量引起的FCC含量的差异会导致合金不同的变形机制。
基金
the National Key Research and Development Program of China (No. 2017YFGX090043)
the Program for New Century Excellent Talents in University, China (No. NCET-12-0170) for supporting this work。
