标题
作者
作者:Yuan, B (Yuan, Bin)[1,2,3 ]; Zheng, PQ (Zheng, Peiqi)[2 ]; Gao, Y (Gao, Yan)[1,3 ]; Zhu, M (Zhu, Min)[1,3 ]; Dunand, DC (Dunand, David C.)[2 ]
期刊信息
摘要
Strain incompatibilities between grains in polycrystalline Cu-Al-Ni shape-memory alloys undergoing stress-induced reversible transformation reduce their ductility and their recoverable superelastic strains on unloading. These strain incompatibilities can be mitigated by creation of large, textured grains through directional solidification or large, bamboo grains intersecting the free surfaces of pores. To study these two approaches to improve superelasticity in Cu-Al-Ni alloys, polycrystalline Cu-13.5Al-4Ni (wt.%) samples were cast in porous and dense form, with and without directional solidification. When tested in compression, directionally-solidified, oligocrystalline bulk (non-porous) Cu-Al-Ni exhibits recoverable unloading strains as high as 6.6% at 210 degrees C, as compared to 3.1% for their conventionally-solidified counterparts. Similarly, when comparing conventionally-solidified Cu-Al-Ni SMA with 58% open porosity shows 1.4% recoverable unloading strain at 260 degrees C, whereas a value of 2.6% is achieved in directionally-solidified porous samples with bamboo grains straddling pores. This improvement in superelasticity remains present after 30 mechanical load-unload cycles at 260 degrees C. Thus, both directional solidification and addition of porosity can reduce strain incompatibilities between neighboring grains in polycrystalline Cu-Al-Ni alloys, allowing them to approach the intrinsic high superelasticity of single crystals. (C) 2015 Elsevier Ltd. All rights reserved.
关键词
作者关键词:High-temperature shape-memory alloy; Cu-Al-Ni alloy; Superelasticity; Porous; Stress-induced transformation
作者信息
通讯作者地址:Yuan, B (通讯作者)
 | S China Univ Technol, Sch Mat Sci & Engn, Guangzhou 510640, Guangdong, Peoples R China. |
地址:
电子邮件地址:apsheng@scut.edu.cn
出版商
类别分类
研究方向:Materials Science
Web of Science 类别:Materials Science, Multidisciplinary