Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, USA.
Phys Rev Lett. 2012 Sep 14;109(11):115704. doi: 10.1103/PhysRevLett.109.115704.
Although nanodispersive precipitation-hardened alloys have been intensively studied over decades as important structural materials, the possibility that these alloys may have superfunctional properties has been completely overlooked. As shown in this Letter, they may have giant low-hysteretic strain responses to external stimuli if the nanosized single-domain precipitates can switch their orientation variants under applied fields. We demonstrate that the misfit-generated coherency stress can significantly reduce the variant switching barriers and may drastically decrease or even eliminate the hysteresis of the strain super responses to external stress and/or magnetic fields. These alloys can thus be functionalized as shape memory, superelastic, and/or supermagnetostrictive materials. The conditions of such functionalization are established by the interpretation-transparent analytical calculations, and confirmed by computer prototyping. In particular, the obtained results pave the way for the engineering of rare-earth free alloys with excellent magnetomechanical and good mechanical properties.
虽然纳米弥散沉淀硬化合金作为重要的结构材料已经被研究了几十年，但人们完全忽略了这些合金可能具有超功能特性的可能性。正如本函中所示，如果纳米级单畴析出物能够在外场作用下改变其取向变体，那么它们可能对外界刺激具有巨大的低滞后应变响应。我们证明，失配产生的相干应力可以显著降低变体转换势垒，并可能大大降低甚至消除应变对外应力和/或磁场的超响应的滞后。因此，这些合金可以用作形状记忆、超弹性和/或超磁致伸缩材料。这种功能化的条件是通过解释透明的分析计算确定的，并通过计算机原型验证。特别是，所得到的结果为具有优异磁机械性能和良好机械性能的无稀土合金的工程设计铺平了道路。
