Abstract
Controlling anisotropy in self-assembled structures enables engineering of materials with highly directional response. Here, we harness the anisotropic growth of ice walls in a thermal gradient to assemble an anisotropic refractory metal structure, which is then infiltrated with Cu to make a composite. Using experiments and simulations, we demonstrate on the specific example of tungsten-copper composites the effect of anisotropy on the electrical and mechanical properties. The measured strength and resistivity are compared to isotropic tungsten-copper composites fabricated by standard powder metallurgical methods. Our results have the potential to fuel the development of more efficient materials, used in electrical power grids and solar-thermal energy conversion systems. The method presented here can be used with a variety of refractory metals and ceramics, which fosters the opportunity to design and functionalize a vast class of new anisotropic load-bearing hybrid metal composites with highly directional properties.
Highlights
The number of materials performing well in extreme environments, such as high temperatures above 2000 °C, high voltage or hazardous radiation fields, is limited and typically comprises high-melting materials, for example oxides[1] and metal alloys based on niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W) and rhenium (Re)
We report on a different approach to create refractory metal-based composites utilizing ice-templating[19,20] in a thermal gradient to assemble an anisotropic refractory metal scaffold which is infiltrated by a second liquid phase
W-Cu composites, we resort to high resolution x-ray computed tomography (XCT)
Summary
The number of materials performing well in extreme environments, such as high temperatures above 2000 °C, high voltage or hazardous radiation fields, is limited and typically comprises high-melting materials, for example oxides[1] and metal alloys based on niobium (Nb), molybdenum (Mo), tantalum (Ta), tungsten (W) and rhenium (Re). These metals, commonly dubbed “refractory metals” and their alloys find wide application in nuclear reactors[2,3], turbines[3], space-crafts[3], thermal emitters[4], heat spreaders[3,5] and circuit breakers[6] in power grids. Detailed information on the synthesis and processing of the tungsten skeleton is given in a previous work[25]
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