Nano-mechanical properties of Fe-Mn-Al-C lightweight steels.
Nano-mechanical properties of Fe-Mn-Al-C lightweight steels.
复制标题
Fe-Mn-Al-C轻质钢的纳米力学性能。
DOI：
10.1038/s41598-018-27345-w
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发表时间：
2018
影响因子：
4.6
通讯作者：
Rahnama A
中科院分区：
文献类型：
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作者：
Rahnama A
高铝低密度钢可能对运输用钢结构的轻量化产生变革性影响。它们可以用最小量的Ni实现所需的性质，因此从经济角度来看具有很大的意义。研究了Fe-15 Mn-10Al-0.8C-5 Ni和Fe-15 Mn-10Al-0.8C（wt.%）两种双相低密度钢的力学性能。通过纳米压痕和利用密度泛函理论（DFT）中的从头算模拟来研究，以建立由两个关键结构特征（κ-碳化物和B2金属间化合物）产生的硬度作为退火温度（500-1050 °C）和添加Ni的函数。在不含Ni的样品中，计算的κ-碳化物的弹性性能与B2金属间化合物Fe 3Al − L12的弹性性能进行了比较，并研究了Mn在κ结构及其弹性性能中的作用。发现含Ni的样品具有较高的硬度，这是由于B2相组成为NiAl而不是FeAl，据报道Ni-Al键比Fe-Al键更强。在两个样品中，在900 °C和更高的温度下，铁素体相包含B2相的纳米尺寸盘，其中含Ni样品表现出更高的硬度，这再次归因于B2相中更强的Ni-Al键。在700 °C及以下，纳米尺寸的B2盘被无Ni样品中的微米尺寸的κ针取代，导致硬度降低。在含Ni的样品中，整个α相被B2纵梁取代，由于在700 °C及以下形成的B2纵梁带中的Ni含量较低，B2纵梁具有比Ni-Al纳米盘更低的硬度。此外，在α相中形成的针状κ型碳化物的硬度与Mn含量有关。虽然由于γ相的纳米尺寸，无法测量立方κ颗粒的硬度，但测量并报道了复合相（例如γ +κ）的硬度值。所有的硬度值进行了比较，并合理化不同原子之间的键能。
High Al Low-density steels could have a transformative effect on the light-weighting of steel structures for transportation. They can achieve the desired properties with the minimum amount of Ni, and thus are of great interest from an economic perspective. In this study, the mechanical properties of two duplex low-density steels, Fe-15Mn-10Al-0.8C-5Ni and Fe-15Mn-10Al-0.8 C (wt.%) were investigated through nano-indentation and simulation through utilization ofab-initioformalisms in Density Functional Theory (DFT) in order to establish the hardness resulting from two critical structural features (κ-carbides and B2 intermetallic) as a function of annealing temperature (500–1050 °C) and the addition of Ni. In the Ni-free sample, the calculated elastic properties ofκ-carbides were compared with those of the B2 intermetallic Fe3Al−L12and the role of Mn in theκstructure and its elastic properties were studied. The Ni-containing samples were found to have a higher hardness due to the B2 phase composition being NiAl rather than FeAl, with Ni-Al bonds reported to be stronger than the Fe-Al bonds. In both samples, at temperatures of 900 °C and above, the ferrite phase contained nano-sized discs of B2 phase, wherein the Ni-containing samples exhibited higher hardness, attributed again to the stronger Ni-Al bonds in the B2 phase. At 700 °C and below, the nano-sized B2 discs were replaced by micrometre sized needles ofκin the Ni-free sample resulting in a lowering of the hardness. In the Ni-containing sample, the entire α phase was replaced by B2 stringers, which had a lower hardness than the Ni-Al nano-discs due to a lower Ni content in B2 stringer bands formed at 700 °C and below. In addition, the hardness of needle-likeκ-carbides formed in α phase was found to be a function of Mn content. Although it was impossible to measure the hardness of cuboidκparticles in γ phase because of their nano-size, the hardness value of composite phases, e.g. γ +κwas measured and reported. All the hardness values were compared and rationalized by bonding energy between different atoms.