Taking Al-2%mole-Cu binary alloy as an example, the influence of grain orientation on competitive growth of dendrites under different competitive modes was investigated by using the three-dimensional(3-D) phasefield m...Taking Al-2%mole-Cu binary alloy as an example, the influence of grain orientation on competitive growth of dendrites under different competitive modes was investigated by using the three-dimensional(3-D) phasefield method. The result of phase-field simulation was verified by applying cold spray and directional remelting. In the simulation process, two competitive modes were designed: in Scheme 1, the monolayer columnar grains in multilayer columnar crystals had different orientations; while in Scheme 2, they had the same orientation. The simulation result showed that in Scheme 1, the growth of the dendrites, whose orientation had a certain included angle with the direction of temperature gradient, was restrained by the growth of other dendrites whose direction was parallel to the direction of temperature gradient. Moreover, the larger the included angle between the grain orientation and temperature gradient, the earlier the cessation of dendrite growth. The secondary dendrites of dendrites whose grain orientation was parallel to the temperature gradient flourished with increasing included angles between the grain orientation and temperature gradient. In Scheme 2, the greater the included angle between grain orientation and temperature gradient, the easier the dendrites whose orientation showed a certain included angle with temperature gradient inserted between those grew parallel to the temperature gradient, and the better the growth condition thereafter. Some growing dendrites after intercalation were deflected to the temperature gradient, and the greater the included angle, the lower the deflection. The morphologies of the competitive growth dendrites obtained through simulation can also be found in metallographs of practical solidification experiments. This implies that the two modes of competitive growth of dendrites characterized in the simulation do exist and frequently appear in practical solidification processes.展开更多
为合理、安全利用微咸水,促进番茄高效可持续生产,以京番301为试验材料,采用沙土槽培、单因素完全随机区组试验,以微咸水(EC=3 m S/cm)直接灌溉为对照,研究了微咸水不同灌溉方式对坐果期、盛果期、盛果后期番茄植株根、茎、叶及不同生...为合理、安全利用微咸水,促进番茄高效可持续生产,以京番301为试验材料,采用沙土槽培、单因素完全随机区组试验,以微咸水(EC=3 m S/cm)直接灌溉为对照,研究了微咸水不同灌溉方式对坐果期、盛果期、盛果后期番茄植株根、茎、叶及不同生育期果实中矿质元素含量的影响。结果表明:(1)番茄植株根、茎、叶及果实中的10种矿质元素含量在生育期内呈规律性的变化,根、茎、叶中6种大量矿质元素含量均为N、K、Ca大于P、Mg、Na,4种微量元素含量以Fe、Mn较高,Zn次之,Cu最低;除K外,幼果期果实中5种大量矿质元素含量最高,K在成熟期果实中含量最高,果实中微量元素含量以Fe、Zn较高,Cu和Mn较低。果实中K含量与其余9种矿质元素含量存在一定的增效作用,而Mg与Zn、Cu、P 3种元素,Na、Mn与Fe、Zn、Cu、P 4种元素间存在一定的拮抗作用。(2)微咸水参与灌溉提高了番茄植株各部位及品质形成期果实中全Na的含量,以微咸水直接灌溉提高幅度最大。与淡水灌溉相比,微咸水直接灌溉植株各部位全N含量也有所提高,但不利于果实对N、P和4种微量元素的吸收与积累。淡水灌溉有利于提高植株各部位全效P、K及Zn的含量,进而促进果实对N、P、K及Fe、Zn的吸收与积累。微咸水淡水按生育期轮灌可提高植株各部位Ca、Mg、Fe的含量,微咸水淡水按次轮灌和按生育期轮灌下幼果期、成熟期果实中Ca、Mg含量也较高。混合水灌溉和按次轮灌植株各部位Cu和Mn含量较高,因此品质形成期混合水灌溉下果实中Cu含量、按次轮灌下果实中Mn含量也较高。综上,短期微咸水灌溉或降低微咸水的矿化度灌溉(轮灌、混合水灌溉)不仅能够节约淡水资源,而且可以有效避免微咸水直接灌溉对植株生长的不利影响,并补充植物所需的N、Ca、Mg、Fe、Mn、Cu等营养元素。展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.:11504149,11364024,51661020)
文摘Taking Al-2%mole-Cu binary alloy as an example, the influence of grain orientation on competitive growth of dendrites under different competitive modes was investigated by using the three-dimensional(3-D) phasefield method. The result of phase-field simulation was verified by applying cold spray and directional remelting. In the simulation process, two competitive modes were designed: in Scheme 1, the monolayer columnar grains in multilayer columnar crystals had different orientations; while in Scheme 2, they had the same orientation. The simulation result showed that in Scheme 1, the growth of the dendrites, whose orientation had a certain included angle with the direction of temperature gradient, was restrained by the growth of other dendrites whose direction was parallel to the direction of temperature gradient. Moreover, the larger the included angle between the grain orientation and temperature gradient, the earlier the cessation of dendrite growth. The secondary dendrites of dendrites whose grain orientation was parallel to the temperature gradient flourished with increasing included angles between the grain orientation and temperature gradient. In Scheme 2, the greater the included angle between grain orientation and temperature gradient, the easier the dendrites whose orientation showed a certain included angle with temperature gradient inserted between those grew parallel to the temperature gradient, and the better the growth condition thereafter. Some growing dendrites after intercalation were deflected to the temperature gradient, and the greater the included angle, the lower the deflection. The morphologies of the competitive growth dendrites obtained through simulation can also be found in metallographs of practical solidification experiments. This implies that the two modes of competitive growth of dendrites characterized in the simulation do exist and frequently appear in practical solidification processes.
文摘为合理、安全利用微咸水,促进番茄高效可持续生产,以京番301为试验材料,采用沙土槽培、单因素完全随机区组试验,以微咸水(EC=3 m S/cm)直接灌溉为对照,研究了微咸水不同灌溉方式对坐果期、盛果期、盛果后期番茄植株根、茎、叶及不同生育期果实中矿质元素含量的影响。结果表明:(1)番茄植株根、茎、叶及果实中的10种矿质元素含量在生育期内呈规律性的变化,根、茎、叶中6种大量矿质元素含量均为N、K、Ca大于P、Mg、Na,4种微量元素含量以Fe、Mn较高,Zn次之,Cu最低;除K外,幼果期果实中5种大量矿质元素含量最高,K在成熟期果实中含量最高,果实中微量元素含量以Fe、Zn较高,Cu和Mn较低。果实中K含量与其余9种矿质元素含量存在一定的增效作用,而Mg与Zn、Cu、P 3种元素,Na、Mn与Fe、Zn、Cu、P 4种元素间存在一定的拮抗作用。(2)微咸水参与灌溉提高了番茄植株各部位及品质形成期果实中全Na的含量,以微咸水直接灌溉提高幅度最大。与淡水灌溉相比,微咸水直接灌溉植株各部位全N含量也有所提高,但不利于果实对N、P和4种微量元素的吸收与积累。淡水灌溉有利于提高植株各部位全效P、K及Zn的含量,进而促进果实对N、P、K及Fe、Zn的吸收与积累。微咸水淡水按生育期轮灌可提高植株各部位Ca、Mg、Fe的含量,微咸水淡水按次轮灌和按生育期轮灌下幼果期、成熟期果实中Ca、Mg含量也较高。混合水灌溉和按次轮灌植株各部位Cu和Mn含量较高,因此品质形成期混合水灌溉下果实中Cu含量、按次轮灌下果实中Mn含量也较高。综上,短期微咸水灌溉或降低微咸水的矿化度灌溉(轮灌、混合水灌溉)不仅能够节约淡水资源,而且可以有效避免微咸水直接灌溉对植株生长的不利影响,并补充植物所需的N、Ca、Mg、Fe、Mn、Cu等营养元素。
