Leitner Alexander, Maier-Kiener Verena, Kiener Daniel
Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben, Austria.
Department Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstraße 12, A-8700 Leoben, Austria; verena.maier
Nanomaterials (Basel). 2018 May 24;8(6):366. doi: 10.3390/nano8060366.
Nanoporous metals have attracted attention in various research fields in the past years since their unique microstructures make them favorable for catalytic, sensory or microelectronic applications. Moreover, the refinement of the ligaments down to the nanoscale leads to an exceptionally high strength. To guarantee a smooth implementation of nanoporous metals into modern devices their thermo-mechanical behavior must be properly understood. Within this study the mechanical flow properties of nanoporous Au were investigated at elevated temperatures up to 300 °C. In contrast to the conventional synthesis by dealloying of AuAg precursors, the present foam was fabricated via severe plastic deformation of an AuFe nanocomposite and subsequent selective etching of iron, resulting in Au ligaments consisting of nanocrystalline grains, while remaining Fe impurities excessively stabilize the microstructure. A recently developed spherical nanoindentation protocol was used to extract the stress-strain curves of nanoporous Au. A tremendous increase of yield strength due to ligament and grain refinement was observed, which is largely maintained at high temperatures. Reviewing literature will evidence that the combined nanocrystalline and nanoporous structure leads to remarkable mechanical properties. Furthermore, comparison to a previous Berkovich nanoindentation study outlines the conformity of different indentation techniques.
在过去几年中，纳米多孔金属因其独特的微观结构使其适用于催化、传感或微电子应用而在各个研究领域受到关注。此外，将金属韧带细化至纳米尺度会带来极高的强度。为确保纳米多孔金属能顺利应用于现代设备，必须充分了解其热机械行为。在本研究中，对纳米多孔金在高达300°C的高温下的机械流动特性进行了研究。与通过脱合金化AuAg前驱体进行的传统合成方法不同，目前的泡沫材料是通过对AuFe纳米复合材料进行严重塑性变形并随后选择性蚀刻铁而制备的，从而得到由纳米晶粒组成的金韧带，而残留的铁杂质会过度稳定微观结构。采用最近开发的球形纳米压痕方法来提取纳米多孔金的应力-应变曲线。观察到由于韧带和晶粒细化导致屈服强度大幅提高，且在高温下基本保持不变。查阅文献可知，纳米晶和纳米多孔结构相结合会产生显著的机械性能。此外，与之前的Berkovich纳米压痕研究进行比较，凸显了不同压痕技术的一致性。
