Refinement of Mg alloys crystal structure via Nb-based heterogeneous substrates for improved performances
Refinement of Mg alloys crystal structure via Nb-based heterogeneous substrates for improved performances
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DOI：
10.1016/j.msea.2018.03.005
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发表时间：
2018-04
期刊：
影响因子：
6.4
通讯作者：
L. Bolzoni;U. Joshi;R. Alain;D. Garetto;N. H. Babu
中科院分区：
文献类型：
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作者：
L. Bolzoni;U. Joshi;R. Alain;D. Garetto;N. H. Babu
轻量化和高比强度使镁合金成为交通运输行业的理想材料，尤其是汽车行业，因为汽车行业正在努力应对日益严格的二氧化碳排放法规。变形镁合金由于其六边形密排晶格中很少有活动滑移系，因而不易变形。因此，大多数商业上可用的镁合金是基于铸造工艺中使用的Mg-Al二元体系的合金。由于Zr铝化物的形成，不能通过Zr晶粒细化来改善这些合金的力学性能。在这项研究中，我们提出了一种新的化学成分，可以精炼所有类型的镁合金，正如在含al的AM50镁合金中所证明的那样。研究表明，Nb-B接种镁合金促进了非均质成核α-Mg初生晶粒的形成，导致晶粒尺寸减小，这是在很宽的冷却速率下获得的。结果表明，合金的晶粒细化改善了高压压铸Mg汽车零部件的性能，并具有提高铸造镁合金力学性能的潜力。
Lightness and high specific strength make magnesium alloys ideal materials for the transportation industry, especially the automotive sector that is struggling to cope with the everyday more stringent regulations on emission of carbon dioxide. Wrought magnesium alloys are difficult to deform because of the few active slip systems characteristic of their hexagonal close-packed lattice. Consequently, most of the commercially available magnesium alloys are alloys based on the Mg-Al binary system used in casting processes. The improvement of the mechanical properties of these alloys cannot be achieved by means of grain refinement using Zr due to the formation of Zr aluminides. In this study we propose a novel chemical composition that can refine all types of Mg alloys as proved in the Al-containing AM50 Mg alloy. We demonstrate that Nb-B inoculation of Mg alloys promotes the formation of heterogeneously nucleated primary α-Mg grains leading to the reduction of the grain size and this is obtained over a wide range of cooling rates. We also show that the grain refinement achieved leads to the improvement of the properties of high pressure die cast Mg automotive components and has the potential to enhance the mechanical properties of cast Mg alloys.