Mo element has been considered as an effective element to regulate the nano-precipitation behavior in low-density steel. In this work, a novel nano-ordered phase was found in austenite of the Fe–28Mn–10Al-1.2C (wt.%) low-density steels with 3 wt% and 5 wt% Mo addition. HRTEM characterization indicated that this nano-ordered phase had a chemical composition similar to austenite matrix and a L′1 structure similar to κ-carbides. Although the Mo addition suppressed the precipitation and growth of κ-carbides in austenite, the nano-hardness testing showed that the formation of the novel nano-ordered phase caused by Mo addition resulted in a higher hardness of austenite. Based on the tensile property analysis of the Mo-containing steels, although the Mo addition decreased the precipitation strengthening of intragranular κ-carbides, the novel nano-ordered phase resulted in an additional strength contribution of 309 MPa. In addition, the formation of this novel nano-ordered phase had significant improvement on the strain hardening rate. Consequently, the Mo addition simultaneously increased the strength and plasticity of the low-density steels. The novel nano-ordered phase caused by Mo has rarely been reported in literatures, its contribution on the strength and strain hardening ability indicated its potential application in the regulation of mechanical properties.

中文翻译：

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通过新型纳米有序相实现含钼低密度钢的意外强化

Mo元素被认为是调节低密度钢纳米析出行为的有效元素。在这项工作中，在添加 3 wt% 和 5 wt% Mo 的 Fe-28Mn-10Al-1.2C (wt.%) 低密度钢的奥氏体中发现了一种新型纳米有序相。HRTEM 表征表明，这种纳米有序相具有类似于奥氏体基体的化学成分和类似于 κ-碳化物的 L'1 结构。虽然Mo的添加抑制了奥氏体中κ-碳化物的析出和生长，但纳米硬度测试表明，Mo的添加导致了新型纳米有序相的形成，导致奥氏体具有更高的硬度。根据含Mo钢的拉伸性能分析，虽然Mo的添加降低了晶内κ-碳化物的沉淀强化，但新型纳米有序相导致额外的强度贡献为309 MPa。此外，这种新型纳米有序相的形成对应变硬化速率有显着的提高。因此，Mo的添加同时提高了低密度钢的强度和塑性。由Mo引起的新型纳米有序相在文献中很少报道，其对强度和应变硬化能力的贡献表明了其在机械性能调控方面的潜在应用。