An experimental and modeling investigation of tensile creep resistance of a stable nanocrystalline alloy
An experimental and modeling investigation of tensile creep resistance of a stable nanocrystalline alloy
复制标题
稳定纳米晶合金拉伸蠕变抗力的实验和建模研究
DOI：
10.1016/j.actamat.2020.08.020
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发表时间：
2020
期刊：
影响因子：
9.4
通讯作者：
Solanki, K.N.
中科院分区：
文献类型：
--
作者：
Kale, C.;Srinivasan, S.;Hornbuckle, B.C.;Koju, R.K.;Darling, K.;Mishin, Y.;Solanki, K.N.
纳米晶（NC）材料具有优异的室温性能，如高强度、耐磨性和韧性，与粗粒度材料相比。然而，由于自由能过剩，NC微结构在高温下是不稳定的。在中等低温下已经观察到明显的晶粒生长，限制了NC材料的广泛适用性。在这里，我们提出了一种设计方法，可以显著提高NC Cu-Ta合金的高温抗拉伸蠕变性能（高达熔化温度的0.64）。设计方法包括将纯元素合金化，在晶粒内和沿晶界形成纳米尺寸的溶质团簇分布。我们证明了Ta纳米团簇的加入抑制了高温下晶界的迁移，减少了位错运动。这导致了极不寻常的拉伸蠕变行为，包括在几乎所有材料中通常观察到的任何明显的稳态蠕变变形的缺失。这种设计策略可以很容易地扩展到抗蠕变数控零件的批量制造，并转移到其他多组分系统，如镍基合金。
Nanocrystalline (NC) materials possess excellent room temperature properties, such as high strength, wear resistance, and toughness as compared to their coarse-grained counterparts. However, due to the excess free energy, NC microstructures are unstable at higher temperatures. Significant grain growth is observed already at moderately low temperatures, limiting the broader applicability of NC materials. Here, we present a design approach that leads to a significant improvement in the high temperature tensile creep resistance (up to 0.64 of the melting temperature) of a NC Cu-Ta alloy. The design approach involves alloying of pure elements to create a distribution of nanometer sized solute clusters within the grains and along the grain boundaries. We demonstrate that the addition of Ta nanoclusters inhibits the migration of grain boundaries at high temperatures and reduces the dislocation motion. This leads to a highly unusual tensile creep behavior, including the absence of any appreciable steady-state creep deformation normally observed in almost all materials. This design strategy can be readily scaled-up for bulk manufacturing of creep-resistant NC parts and transferred to other multicomponent systems such as Ni-based alloys.