Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 2012 Aug 24;337(6097):951-4. doi: 10.1126/science.1224737.
Nanostructured metals are generally unstable; their grains grow rapidly even at low temperatures, rendering them difficult to process and often unsuitable for usage. Alloying has been found to improve stability, but only in a few empirically discovered systems. We have developed a theoretical framework with which stable nanostructured alloys can be designed. A nanostructure stability map based on a thermodynamic model is applied to design stable nanostructured tungsten alloys. We identify a candidate alloy, W-Ti, and demonstrate substantially enhanced stability for the high-temperature, long-duration conditions amenable to powder-route production of bulk nanostructured tungsten. This nanostructured alloy adopts a heterogeneous chemical distribution that is anticipated by the present theoretical framework but unexpected on the basis of conventional bulk thermodynamics.
纳米结构金属通常不稳定；即使在低温下，它们的晶粒也会迅速生长，这使得它们难以加工，而且通常不适合使用。合金化已被发现可以提高稳定性，但仅限于少数经验发现的系统。我们已经开发出一种理论框架，可以用它来设计稳定的纳米结构合金。一个基于热力学模型的纳米结构稳定性图谱被应用于设计稳定的纳米结构钨合金。我们确定了一种候选合金 W-Ti，并证明了在高温、长时间条件下的稳定性有了显著提高，而这些条件是粉末途径生产大块纳米结构钨所需要的。这种纳米结构合金采用了一种不均匀的化学分布，这是目前的理论框架所预期的，但根据传统的块状热力学是意料之外的。
