Fully reversible, dislocation-based compressive deformation of Ti3SiC2 to 1GPa
Fully reversible, dislocation-based compressive deformation of Ti3SiC2 to 1GPa
复制标题
DOI：
10.1038/nmat814
复制
发表时间：
2003-02-01
期刊：
影响因子：
41.2
通讯作者：
Murugaiah, A
中科院分区：
文献类型：
--
作者：
Barsoum, MW;Zhen, T;Murugaiah, A
结晶固体中基于位错的变形几乎总是塑性的。在这里，我们发现在室温下循环加载Ti3SiC2的多晶样品，在压缩中，应力高达1 GPa，在去除负载时完全恢复，同时耗散约25% （0.7 MJ m(-3)）的机械能。应力-应变曲线勾勒出完全可逆的、速率无关的、封闭的磁滞回线，该磁滞回线受晶粒尺寸的强烈影响，其中粗粒材料的能量耗散明显更大。当温度高于1000℃时，环是打开的，响应取决于应变速率，并且观察到循环硬化。这一迄今未被报道的现象归因于在室温变形中初始扭结带的可逆形成和湮灭。在较高的温度下，初始的扭结带解离并结合形成规则的不可逆扭结带。Ti3SiC2的损耗系数高于大多数木材，与聚丙烯和尼龙相当。讨论了具有刚性，轻质可加工陶瓷的技术含义，该陶瓷可以在每个循环中耗散高达25%的机械能。
Dislocation-based deformation in crystalline solids is almost always plastic. Here we show that polycrystalline samples of Ti3SiC2 loaded cyclically at room temperature, in compression, to stresses up to 1 GPa, fully recover on the removal of the load, while dissipating about 25% (0.7 MJ m(-3)) of the mechanical energy. The stress-strain curves outline fully reversible, rate-independent, closed hysteresis loops that are strongly influenced by grain size, with the energy dissipated being significantly larger in the coarse-grained material. At temperatures greater than 1,000 degreesC, the loops are open, the response is strain-rate dependent, and cyclic hardening is observed. This hitherto unreported phenomenon is attributed to the reversible formation and annihilation of incipient kink bands at room-temperature deformation. At higher temperatures, the incipient kink bands dissociate and coalesce to form regular irreversible kink bands. The loss factor for Ti3SiC2 is higher than most woods, and comparable to polypropylene and nylon. The technological implications of having a stiff, lightweight machinable ceramic that can dissipate up to 25% of the mechanical energy per cycle are discussed.