Interactive contraction nanotwins-stacking faults strengthening mechanism of Mg alloys
Interactive contraction nanotwins-stacking faults strengthening mechanism of Mg alloys
复制标题
镁合金交互收缩纳米孪晶-堆垛层错强化机制
DOI：
10.1016/j.actamat.2019.02.040
复制
发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
Jianyu Huang
中科院分区：
文献类型：
--
作者：
Qiuming Peng;Yong Sun;Bingcheng Ge;Hui Fu;Qun Zu;Xiaozhi Tang;Jianyu Huang
高强度轻质镁合金具有高刚度、原料丰富、环境友好等优点，在交通运输、航空航天、电子元器件和植入物等领域有着广泛的应用前景。然而，大多数传统的强化方法，包括晶粒细化和沉淀强化，可以有效地阻止位错运动，以及妥协的韧性不变。在这里，我们报告了一种新的策略，同时实现高的比屈服强度（182 ± 8 kNmKg-1）和良好的伸长率（21 ± 2%）在Mg-13重量%的锂在室温下，基于形成一个分层收缩纳米孪晶堆垛层错（CTWSF）结构，通过低温轧制，然后再加压。它们都是迄今为止报道的最高值，即使与商业Al/Ti合金和钢相比。通过离位透射电子显微镜观察和分子动力学模拟，阐明了其形成过程和强化机制。结果表明，这种独特的纳米级交互共格界面结构类似于孪晶界，能有效抑制Mg晶体中的位错运动。这些新结果为设计具有更高机械性能的替代和更具创新性的HCP型结构材料提供了见解。
Light-weight Mg alloys with higher strength are especially desirable for the applications in transportation, aerospace, electronic components and implants owing to their high stiffness, abundant raw materials and environmental friendliness. Nevertheless, the majority of traditional strengthening approaches involving grain refining and precipitation strengthening could effectively prohibit dislocation movement as well as compromise ductility invariably. Here we report a novel strategy for simultaneously achieving a high specific yield strength (182 ± 8 kNmKg−1) and a good elongation (21 ± 2%) in the Mg-13 wt% Li at room temperature, based on the formation of a hierarchical contraction nanotwins-stacking faults (CTWSFs) structure by cryorolling followed by ultrahigh pressure. Both of them are the highest values reported so far, even compared to commercial Al/Ti alloys and steel. The formation process and strengthening mechanism have been clarified byex-situtransmission electron microscopy observation and molecule dynamics simulations. It demonstrates that this unique nanoscale interactive coherent interface structure is effective to prohibit dislocation motion in Mg crystal, analogous to twin boundaries. Those new results provide insights towards designing alternative and more innovative HCP-type structural materials with higher mechanical properties.