Shape Memory and Superelastic Ceramics at Small Scales
Shape Memory and Superelastic Ceramics at Small Scales
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DOI：
10.1126/science.1239745
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发表时间：
2013-09-27
期刊：
影响因子：
56.9
通讯作者：
Schuh, Christopher A.
中科院分区：
文献类型：
--
作者：
Lai, Alan;Du, Zehui;Schuh, Christopher A.
形状记忆材料是一类智能材料，能够通过马氏体相变将热转化为机械应变(或应变)。一些脆性材料，如金属间化合物和陶瓷，表现出马氏体相变，但在低应变下和仅在几次施加应变循环后就会破裂。在这里，我们表明，在正常脆性的马氏体陶瓷中，可以通过提供细小的结构和很少的晶粒来抑制这种破坏。这种寡晶结构减少了马氏体相变过程中的内部失配应力，并导致了坚固的形状记忆陶瓷，这种陶瓷能够承受多个超弹性循环，直到大应变；在这里，我们描述了循环多达50次的样品和能够承受7%以上应变的样品。具有这些特性的形状记忆陶瓷代表了一类新的致动器或智能材料，具有一系列特性，包括高能量输出、高能量衰减和高温使用。
Shape memory materials are a class of smart materials able to convert heat into mechanical strain (or strain into heat) by virtue of a martensitic phase transformation. Some brittle materials such as intermetallics and ceramics exhibit a martensitic transformation but fail by cracking at low strains and after only a few applied strain cycles. Here we show that such failure can be suppressed in normally brittle martensitic ceramics by providing a fine-scale structure with few crystal grains. Such oligocrystalline structures reduce internal mismatch stresses during the martensitic transformation and lead to robust shape memory ceramics that are capable of many superelastic cycles up to large strains; here we describe samples cycled as many as 50 times and samples that can withstand strains over 7%. Shape memory ceramics with these properties represent a new class of actuators or smart materials with a set of properties that include high energy output, high energy damping, and high-temperature usage.