摘要
通过光学显微镜（OM）、扫描电镜（SEM）和X射线衍射（XRD）研究了Mg-6Zn-xCa（x=0~1.35）合金的铸态和挤压态组织与相组成,测试了其室温力学性能。结果表明,随着Ca含量的增加,铸态组织逐渐细化,生成的Mg6Zn3Ca2相逐渐增多,而MgZn2相逐渐减少直至完全消失,第二相趋于连续网状分布于晶界处;挤压态组织明显细化,且平均晶粒尺寸从Mg-6Zn合金的15μm逐渐减至Mg-6Zn-0.47Ca合金的10μm。随着Ca含量的增加,铸态抗拉强度、屈服强度和伸长率先从Mg-6Zn合金的154MPa、67MPa、6.5%分别提高至Mg-6Zn-0.085Ca合金的230MPa、84MPa、14%,然后逐渐降低。挤压态力学性能明显提高,加入少量Ca（0.085%）后,抗拉强度和屈服强度稍降低,伸长率提高,而加入较多量Ca（0.47%）后,力学性能明显恶化。
Microstructures and phase compositions of as-cast and extruded Mg-6Zn-xCa（x=0~1.35）alloys were investigated by optical microscopy（OM）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,and the tensile mechanical properties were tested at ambient temperature.The results show that as-cast microstructure is refined and Mg6 Zn3 Ca2 new phase is increased gradually with increasing in Ca content,while MgZn2 phase is decreased gradually until to disappear completely.The second phase tends to distribute along grain boundary with continuous reticulation.Extruded microstructure is refined obviously,where the average grain size is decreased from 15μm for Mg-6Zn alloy to 10μm for Mg-6Zn-0.47Ca alloy.With increasing in the Ca content,tensile strength,yield strength and elongation are firstly increased from 154MPa,67MPa and 6.5%for as-cast Mg-6Zn alloy to 230MPa,78MPa and 13%for as-cast Mg-6Zn-0.085Ca alloy,respectively,and then decreased gradually.Mechanical properties of the alloy is enhanced obviously with 0.085% Ca addition,where the tensile strength and yield strength are decreased lightly,while elongation is increased.However,mechanical properties are deteriorated significantly with more content of Ca（0.47%）addition.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2014年第1期96-101,共6页
Special Casting & Nonferrous Alloys
基金
广东省产学研重大资助项目(2010A090200078)
广东省中国科学院全面战略合作项目资助项目(2011A090100004)
