Shape-memory NiTi foams produced by solid-state replication with NaF

被引：108

作者：

Bansiddhi, Ampika ^{[1
]}

Dunand, David C. ^{[1
]}

机构：

[1] Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA

来源：

INTERMETALLICS | 2007年 / 15卷 / 12期

基金：

美国国家科学基金会;

关键词：

intermetallics; miscellaneous; shape-memory effects; hot isostatic pressing;

D O I：

10.1016/j.intermet.2007.06.013

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

A martensitic NiTi foam was produced by hot isostatic pressing a blend of NiTi and NaF powders and subsequent dissolution of the NaF phase. The NiTi foam consists of 40 vol.% near-fully open pores, 240 pm in size, and with ragged surfaces due to incomplete NiTi powder densification. Near linear stress-strain curves are measured in compression with an average loading stiffness of 4 GPa, well below the unloading stiffness of 13 GPa because of detwinning on loading. Shape-memory recovery after unloading corresponds to 85-89% of the unloading plastic strain. After sintering at 1250 degrees C, the foam exhibits 20% porosity, smaller, smoother and partially-closed pores, and a shift in composition towards a martensite/austenite mixture at ambient temperature. This new composition allows for the activation of the superelastic effect in the austenite during loading and unloading resulting in average stiffnesses of 6-12 GPa, and the shape-memory effect in the martensite with 60-97% of the plastic strain recoverable. (c) 2007 Elsevier Ltd. All rights reserved.

引用

页码：1612 / 1622

页数：11

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