Tech note: Nitinol Wire Braided Components

Reference Library

Nitinol: The Book. An Introduction

Today we introduce an exciting new original series to Over twenty years have passed since the famously out-of-print Engineering Aspects of Shape Memory Alloys was published. In the subsequent decades, Tom Duerig, Alan Pelton, and colleagues here at NDC have learned quite a bit, and we’ve set out to write it all down in a comprehensive and practical guide to the science and engineering aspects of Nitinol. In the coming weeks and months, join us here as we publish a series of excerpts from this forthcoming volume, and welcome your comments on the content along the way. Read on to begin the adventure with a short introduction by Tom.

1.0 Preface

This post is an excerpt from Nitinol: The Book, a working draft of an upcoming publication by Tom Duerig, Alan Pelton, and others. Visit the Table of Contents or Introduction for more information.

This book is targeted towards defining and understanding the engineering and design properties of Nitinol, or nickel-titanium alloys. Compared to most engineering materials, these alloys are complex, and surprises sometimes present themselves from unexpected quarters. For example, a medical device designer that attempts to treat superelastic Nitinol as if it were just a springy stainless steel will undoubtedly encounter problems with fatigue, shelf life, and/or biocompatibility. Designing in a more holistic manner, considering all the unique aspects of Nitinol, can improve on these very same characteristics. It is for this reason that engineers should not just “look up data” on the properties of interest, but rather must develop a thorough, holistic understanding of the alloy and the scientific mechanisms that give rise to the shape memory and superelastic effects. The depth of these more theoretical discussions can and has been reduced in this book as much as deemed possible, but readers are strongly encouraged not to skip topics that may seem at first somewhat esoteric.

It should also be noted that this book also focuses on Nitinol, with little mention of other shape memory alloys. Of course, other shape memory alloys do exist, and while they may not be of commercial import now, they may become so in the future. A brief summary of these other alloys is presented in Chapter 1.

The book is organized in four parts:

  • Part I:  Mechanisms, Characteristics and Properties of Nitinol
  • Part II:  Alloying, Processing and Manufacturing
  • Part III:  Engineering Principles and Applications
  • Part IV:  Medical Product Design

Many sections will end with a few “Advanced Topics.” These are not intended for first-time readers, but rather to serve as reference sections for those already knowledgeable in the field. No Advanced Topics are required background for understanding later subjects in the book, and many will assume knowledge that goes beyond the material that has been previously treated in the book. “Suggested Experiments” are also provided at the end of many sections. Although some are easily performed, many are not and are better considered as “thought experiments.” It is felt, however, that simply reading through these experiments, even if they are never performed, will help solidify the content of the section.

Building a reference library is an essential part of any effort to develop profound expertise in a new field. Finding a complete set of relevant papers is an impossible task, but locating a few books that one can refer to now and then is certainly advised. Below is a list of references we find ourselves using more than others:

  • In 1975, Jeff Perkins conducted the first dedicated Shape Memory conference in Monterey. The proceedings represents the first bound volume dedicated to the shape memory effect.  While of little technical value today, it is interesting to read the state of the art during those early years.  See J Perkins, ed., Shape Memory Effects in Alloys, Plenum Press, NY, (1975) [ISBN 0-306-30891-6].
  • The first bound volume dedicated to engineering with shape memory alloys is the Engineering Aspects of Shape Memory Alloys.  Though an edited collection of papers, all the papers are invited and extensively edited to provide continuity.  Unfortunately, the book is now out of print. See T Duerig, KN Melton, D Stöckel and CM Wayman, eds., Engineering Aspects of Shape Memory Alloys, Butterworth-Heinneman (1990) [ISBN 0-750-61009-3].

A series of ICOMAT conferences, some out of print, provide extremely valuable fundamental information regarding martensitic transformation, and really allow readers to look at the science behind shape memory and superelasticity as it unfolded from about 1979 onwards. The availability and quality of these proceedings is inconsistent; some are very difficult to obtain. Below is a list that may be of some value:

  • ICOMAT 1979: edited and published by the MIT Dept. of Materials Science and Engineering, Cambridge, MA.
  • L Delay and M Chandrasekaran, eds., ICOMAT 1982: J. Physique C-4, no. 12 (December 1982).
  • ICOMAT-86:  Proc. Of the International Conference on Martensitic Transformations, the Japan Inst. of Metals (1987).  (Highly recommended)
  • BC Muddle, ed , ICOMAT 1989: Materials Science Forum 56-58 (1990).
  • CM Wayman and J Perkins, eds., ICOMAT 1992: Proceedings of the International Conference on Martensitic Transformations (published by Monterey Inst. of Advanced Studies, Carmel, CA) (1993).
  • R Gotthardt and J Van Humbeeck, eds., ICOMAT 1995:  J. Physique IV C-8 no. 12 (1995).
  • M Koiwa et al, eds.,  ICOMAT 98: Materials Science & Engineering 273-275, December 1999  [ISSN 0921-5093].
  • T Ko, TY Hsu, LC Zhao and G Kostorz ICOMAT 2005: Mater. Sci. Eng.

Proceedings from the SMST (Shape Memory and Superelastic Technologies) conferences probably represent the best resource for designers and engineers.  Proceedings from the years 1994, 1997, 2000, 2003 and 2004 are available through ASM International. At the time of writing, all are still available, though stock of early proceedings are becoming scarce. The SMST-2001 proceedings were published in conjunction under the auspices of Materials Science Forum 394-395, Trans Tech Publications (2002) [ISBN 0-87849-896-6].

Hiroyasu Funukubo, Shape Memory Alloys, Gordon and Breach, NY, NY (1987) [ISSN 0889-860x] is one of the few early books on the shape memory effect that is authored rather than edited.  As such, it provides better continuity than many other references. While a great deal of valuable data is provided, coverage is far from complete, and there is a great deal of focus on certain specific theoretical topics. Still, it contains invaluable information, much of which cannot be found elsewhere.

V Brailovski et al, eds., Shape Memory Alloys: Fundamentals, Modeling and Applications, Université du Québec (2003) [ISBN 2-921145-42-1] is a new book, based on orchestrated contributions from several scientists.  It is not a particularly good tutorial or text, and has gaping holes in coverage. Nevertheless, much of the information presented is derived from Russian literature that would otherwise be very difficult to obtain, and which describes work not found in journals published in the English-language. We highly recommend it for that reason.

The Materials Research Society has produced several symposium proceedings on shape memory that are superb, though somewhat more scientific than practical.

  • M Doyama, S Somiya and R Chang, eds., Proc. MRS Inter. Mtg. On Adv. Materials vol. 9, Shape Memory Materials, MRS (1989).
  • CT Liu, H Kunsmann, K Otsuka and M Wuttig, eds., MRS Symposium Proc, vol. 246, Shape Memory Materials and Phenomena—Fundamental Aspects and Applications, MRS (1992). [ISBN 1-55899-140-9]
  • EP George, et al, eds.MRS Symposium Proc, vol. 360, Materials for Smart Systems, MRS (1995). [ISBN 1-55899-261-8]

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