Loss of pseudoelasticity in nickel-titanium sub-micron compression pillars
Loss of pseudoelasticity in nickel-titanium sub-micron compression pillars
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DOI：
10.1016/j.actamat.2007.02.034
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发表时间：
2007-04
期刊：
影响因子：
9.4
通讯作者：
C. Frick;S. Orso;E. Arzt
中科院分区：
文献类型：
--
作者：
C. Frick;S. Orso;E. Arzt
镍钛（NiTi）能够经历伪弹性变形，其中相对大量的非弹性变形在载荷去除后由于马氏体相变而恢复。研究了亚微米直径镍钛压缩柱的假弹性变形和塑性变形。利用聚焦离子束微加工时效[111]单晶NiTi，制备了直径约为2μm ~ 200nm的柱状材料。结果显示，直径在2μm到400nm之间的所有样品都具有伪弹性，尽管与体块相比，在相对较低的应变下引入了永久应变。减小的样品尺寸通常表现出较小的应力-应变滞后，对于直径小于200nm的样品，可恢复的假弹性应变完全丧失。此外，时效NiTi材料的马氏体塑性流变应力与试样直径无关。最后，观察到晶体取向对马氏体塑性流动强度的影响大于柱尺寸。
Nickel–titanium (NiTi) is capable of undergoing pseudoelastic deformation wherein relatively large amounts of inelastic deformation are recovered upon load removal due to a martensitic phase transformation. This study investigates pseudoelastic as well as plastic deformation in sub-micron diameter NiTi compression pillars. Pillars ranging in diameter from approximately 2μm to 200nm were prepared using focused ion beam micro-machining of aged [111] single crystal NiTi. Results reveal pseudoelasticity in all samples tested with diameters between 2μm and 400nm, although permanent strain was introduced at relatively low strains compared to bulk. Decreased sample size generally showed a smaller stress–strain hysteresis, with a full loss of recoverable pseudoelastic strain for samples with a diameter smaller than 200nm. In addition, plastic flow stress of the martensite was shown to be independent of sample diameter for the aged NiTi material. Lastly, it is observed that crystallographic orientation has a stronger influence on martensite plastic flow strength than pillar size.