摘要：Mg-Zn-Ca-Mn series alloys are developed as promising candidates of 5G communication devices with excellent thermal conductivities,great ductility,and acceptable *** present paper,Mg-x Zn-0.4Ca-0.2Mn(x=2wt%,4wt%,6wt%)alloys were prepared by a near-solidus extrusion and the effect of Zn content on mechanical and thermal properties were *** results showed that the addition of minor Ca led to the formation of Ca_(2)Mg_(6)Zn_(3) eutectic phase at grain boundaries.A type of bimodal microstructure occurred in the as-extruded alloys,where elongated coarse deformed grains were embedded in refined recrystallized grains ***,both yield strength and ductility of the alloys were significantly enhanced after extrusion due to the great grain ***,higher Zn content led to the increment in yield strength and a slight reduction in elongation due to the larger fractions of second phase *** room temperature thermal conductivity of as-extruded alloys was also improved compared with that of as-cast *** increment of Zn content decreased the thermal conductivity of both as-cast and as-extruded alloys,which was due to the increased second phase fraction and solution atoms in the matrix,that hindering the motion of *** as-extruded Mg-2Zn-0.4Ca-0.2Mn(wt%)alloy exhibited the highest elongation of 27.7% and thermal conductivity of 139.2 W/(m·K),combined with an acceptable ultimate tensile strength of 244.0 *** present paper provides scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity.

摘要：以福州海岛上受马缨丹(Lantana camara)入侵的台湾相思(Acacia confusa)林和桉树(Eucalyptus)林为研究对象,运用生态位宽度、生态位重叠、方差比率法、χ^(2)检验、M. Godron稳定性等方法,对马缨丹入侵群落的物种生态位、种间联结及群落稳定性进行分析。结果表明:马缨丹重要值在台湾相思和桉树林下均居前列,其生态位宽度值最大,占显著优势地位。两种林下马缨丹入侵群落的生态位重叠值总体较低,但马缨丹与台湾相思林下的豺皮樟(Litsea rotundifolia)、两面针(Zanthoxylum nitidum)、了哥王(Wikstroemia indica)、紫弹树(Celtis biondii)等及桉树林下的豺皮樟、鸡屎藤(Paederia cruddasiana)、雀梅藤(Sageretia thea)、两面针等物种存在较高的生态位重叠。台湾相思林下马缨丹入侵群落总体联结性为不显著正联结,正负联结比值大于1;桉树林下马缨丹入侵群落总体联结性为显著负联结,正负联结比值小于1。两种林下15种优势物种的χ^(2)检验结果显示,马缨丹入侵群落种间联结性总体较弱,物种独立性较强,但马缨丹与生态位重叠高的物种存在较强的种间关联性。两种林下马缨丹入侵群落的M. Godron稳定性测定结果均远离理想稳定点坐标(20,80),处于不稳定状态,相对而言,台湾相思林下马缨丹入侵群落的稳定性更高。马缨丹在两种林下均占有绝对优势,入侵群落较不稳定。