Phase behavior and mechanical properties of Ni–W studied by first-principles calculations and ab initio based thermodynamics
Phase behavior and mechanical properties of Ni–W studied by first-principles calculations and ab initio based thermodynamics
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DOI：
10.1016/j.actamat.2014.04.029
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发表时间：
2014-08
期刊：
影响因子：
9.4
通讯作者：
N. Schindzielorz;K. Nowak;S. Maisel;S. Müller
中科院分区：
文献类型：
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作者：
N. Schindzielorz;K. Nowak;S. Maisel;S. Müller
采用基于密度泛函理论计算的团簇展开哈密顿方法研究了面心立方富Ni-W合金的置换有序化现象。我们观察到在Ni-W中有很强的有序化趋势，其特征是沿<；100>；方向形成钨链。虽然以前的研究只报道了化学计量比为Ni4W的D1a型化合物具有这种有序化趋势，但我们预测，在钨在镍中的溶解度范围内，即使在高温下，具有钨<；100>；链的结构也是短程有序化的主要形式。特别是，我们发现了一种Pt8Ti结构的化合物(这也表明了这种有序性)在低温和低钨含量下在Ni-W中是稳定的。即使在高温下，Ni-W固溶体也表现出很强的剩余有序性。从冶金的角度讨论了这些发现的意义，重点讨论了钨合金化对富镍基体的硬化效应。然后，利用这些关于短程有序的见解，我们确定了依赖于组成的刚化Cij‾(X W)和∂Cij‾/∂x W的参数化。
The substitutional ordering phenomena of face-centered cubic Ni-rich Ni–W alloys are investigated by means of cluster-expansion Hamiltonians based on density functional theory calculations. We observe a strong tendency for ordering in Ni–W characterized by the formation of tungsten chains along the< 100> direction. While previous studies only report a D 1 a-type compound at a stoichiometry of Ni 4 W with this< 100>-ordering tendency, we predict that within the solubility range of tungsten in nickel, structures with tungsten< 100>-chains are the predominant form of short-range order even at elevated temperatures. In particular, we find a Pt 8 Ti-structured compound (which also shows this< 100>-ordering) to be stable in Ni–W at low temperatures and low tungsten contents. Even at high temperatures, Ni–W solid solutions are found to exhibit strong remnant order. The implications of these findings are discussed from a metallurgical perspective with an emphasis on the stiffening effect of tungsten alloying on Ni-rich matrices. Using these insights on the short-range order, we then determine a parametrization of the composition-dependent stiffening c ij‾(x W) and∂ c ij‾/∂ x W.