Download or read book Characterization of High Temperature Shape Memory Alloys in the Ni Ti Pt Ternary System written by Grant A. Hudish and published by . This book was released on 2009 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanical and Functional Behavior of High temperature Ni Ti Pt Shape Memory Alloys written by and published by . This book was released on 2016 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of Ti-rich Ni-Ti-Pt ternary alloys with 13 to 18 at. pct Pt were processed by vacuum arc melting and characterized for their transformation behavior to identify shape memory alloys (SMA) that undergo transformation between 448 K and 498 K (175 °C and 225 °C) and achieve recoverable strain exceeding 2 pct. From this broader set of compositions, three alloys containing 15.5 to 16.5 at. pct Pt exhibited transformation temperatures in the vicinity of 473 K (200 °C), thus were targeted for more detailed characterization. Preliminary microstructural evaluation of these three compositions revealed a martensitic microstructure with small amounts of Ti2(Ni, Pt) particles. Room temperature mechanical testing gave a response characteristic of martensitic de-twinning followed by a typical work-hardening behavior to failure. Elevated mechanical testing, performed while the materials were in the austenitic state, revealed yield stresses of approximately 500 MPa and 3.5 pct elongation to failure. Thermal strain recovery characteristics were more carefully investigated with unbiased incremental strain-temperature tests across the 1 to 5 pct strain range, as well as cyclic strain-temperature tests at 3 pct strain. As a result, the unbiased shape recovery results indicated a complicated strain recovery path, dependent on prestrain level, but overall acceptable SMA behavior within the targeted temperature and recoverable strain range.
Download or read book Shape Memory Alloys written by M. Fremond and published by Springer. This book was released on 2014-05-04 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of two chapters. The first chapter deals with the thermomechanical macroscopic theory describing the transformation and deformation behavior of shape memory alloys. The second chapter deals with the extensive and fundamental review of the experimental works which include crystallography, transformations and mechanical characteristics in Ti-Ni, Cu-base and ferrous shape memory alloys.
Download or read book Shape Memory Alloys written by Francisco Manuel Braz Fernandes and published by BoD – Books on Demand. This book was released on 2013-04-03 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shape memory alloys have become in the past decades a well established research subject. However, the complex relations between properties and structure have created a continuously growing interest for a deeper insight all this time. The complexity of relationships between structure and properties is mostly related to the fact that strong ?multidimensional? interactions are taking place: from the early studies focusing on the thermal and/or mechanical induced phase transformations to the more recent findings on the magnetically induced structural changes. On the other hand, these singular behavioral characteristics have driven a great industrial interest due to the innovative aspects that the applications of shape memory alloys may provide. This makes this subject a highly attractive source of continuous studies, ranging from basics crystallography and thermodynamics to mechanical analysis and electrical and magnetic properties characterization. In this book, a group of recent studies is compiled focusing on a wide range of topics from processing to the relationship between the structure and properties, as well as new applications.
Download or read book Alloy Development and High Energy X Ray Diffraction Studies of NiTiZr and NiTiHf High Temperature Shape Memory Alloys written by Matthew A. Carl and published by . This book was released on 2018 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: NiTi-based shape memory alloys (SMAs) offer a good combination of high-strength, ductility, corrosion resistance, and biocompatibility that has served them well and attracted the attention of many researchers and industries. The alloys unique thermo-mechanical ability to recover their initial shape after relatively large deformations by heating or upon unloading due to a characteristic reversible phase transformation makes them useful as damping devices, solid state actuators, couplings, etc. However, there is a need to increase the temperature of the characteristic phase transformation above 150 °C, especially in the aerospace industry where high temperatures are often seen. Prior researchers have shown that adding ternary elements (Pt, Pd, Au, Hf and Zr) to NiTi can increase transformation temperatures but most of these additions are extremely expensive, creating a need to produce cost-effective high temperature shape memory alloys (HTSMAs). Thus, the main objective of this research is to examine the relatively unstudied NiTiZr system for the ability to produce a cost effective and formable HTSMA. Transformation temperatures, precipitation paths, processability, and high-temperature oxidation are examined, specifically using high energy X-ray Diffraction (XRD) measurements, in NiTi-20 at.% Zr. This is followed by an in situ XRD study of the phase growth kinetics of the favorable H-phase nano precipitates, formed in NiTiHf and NiTiZr HTSMAs, based on prior thermo-mechanical processing in a commercial NiTi-15 at.% Hf HTSMA to examine the final processing methods and aging characteristics. Through this research, knowledge of the precipitation paths in NiTiZr and NiTiHf HTSMAs is extended and methods for characterization of phases and strains using high energy XRD are elucidated for future work in the field.
Download or read book Processing and Characterization of High temperature Nickel titanium hafnium Shape Memory Thin Films written by Jinping Zhang and published by . This book was released on 2002 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Ni RICH NiTiHf Based High Temperature Shape Memory Alloys written by Gurdish S. Ded and published by . This book was released on 2010 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Engineering Aspects of Shape Memory Alloys written by T W Duerig and published by Butterworth-Heinemann. This book was released on 2013-10-22 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: Engineering Aspects of Shape Memory Alloys provides an understanding of shape memory by defining terms, properties, and applications. It includes tutorials, overviews, and specific design examples—all written with the intention of minimizing the science and maximizing the engineering aspects. Although the individual chapters have been written by many different authors, each one of the best in their fields, the overall tone and intent of the book is not that of a proceedings, but that of a textbook. The book consists of five parts. Part I deals with the mechanism of shape memory and the alloys that exhibit the effect. It also defines many essential terms that will be used in later parts. Part II deals primarily with constrained recovery, but to some extent with free recovery. There is an introductory paper which defines terms and principles, then several specific examples of products based on constrained recovery. Both Parts III and IV deal with actuators. Part III introduces engineering principles while Part IV presents several of the specific examples. Finally, Part V deals with superelasticity, with an introductory paper and then several specific examples of product engineering.
Download or read book SMST 2006 written by Brian A. Berg and published by ASM International. This book was released on 2008-01-01 with total page 815 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thermal Analysis for Characterizing Effects of Metallurgical Conditions in Nickel Titanium Based Shape Memory Alloys written by Blake Miller and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shape memory alloys (SMAs) undergo a diffusionless solid state transformation (referred as the martensitic transformation) from the high temperature, parent phase austenite to the low temperature, product phase martensite. SMAs recover deformation due to heating, referred to as the shape memory effect (SME). They recover deformation elastic limits beyond typical via unloading, referred as the superelastic effect (SE). Binary NiTi is a specific SMA having properties determined by its Ni composition. Additive manufacturing is important as the layer-by-layer deposition process under desired parameter development allows for microstructure development of NiTi SMAs. Additive manufactured SMAs utilizing Ni-rich compositions (greater than 50.5 at. % / 55.57 wt. % Ni) have been utilized in characterization of the superelastic response. To a lesser extent, research has also used Ti-rich (less than 49.5 at. % / 54.6 wt. % Ni) and near equiatomic (between 49.5 at. %/ 54.6 wt. % and 50.5 at. % / 55.57 wt. % Ni) for studying the SME and SE in NiTi. Primarily research has utilized powder bed fusion (PBF) additive manufacturing while this work looks towards laser directed energy deposition (LDED). This thesis covers Ti-rich LDED NiTi alloys and is one of few to date to report on it. Characterization of the martensitic transformation/shape memory response and subsequent optimization of the thermoelastic properties begins with assessing the thermal-induced shape memory behavior using differential scanning calorimetry (DSC). DSC allows for the ability to determine the temperature ranges for the SME and SE of AM NiTi. DSC uses temperature cycling to measure changing heat flow and endothermic/exothermic events. Endothermic events occur during heating from martensite to austenite (the forward transformation) while exothermic events occur during cooling from austenite to martensite (the reverse transformation). Standard DSC characterization records measurements such as the start, peak, and end temperatures of the forward and reverse transformations. Laser-directed energy deposition (LDED) was used for fabricating Ti-rich AM build coupons which utilized elementally blended Ti and Ni powder feedstock. The layer-by-layer depositions vary in build sizes and thus produce builds with different thermal histories and metallurgical conditions. The first series of build coupons were fabricated as oversized build preforms from which tensile and compression specimens were micromachined. The oversized build preforms have volumes varying between 1500-3950mm3 (XYZ, XZYA, XZYB) and referred to as G0. The second series of build coupons were fabricated as near-net builds with dimensioning close to the designated tension and compression specimens. The near-net builds, referred to as G2, have as-deposited volumes of 2231.4 mm3 for the XYZ build and 3296.5 mm3 for the XZYA build. Specimens were extracted from the fabricated builds with precision wire EDM. DSC is used to study the stress free thermal induced martensitic transformation (TIMT). Standard DSC is performed and its metrics recorded for insight of the TIMT for the AM builds. Standard DSC characterization is augmented to provide advanced metrics for insight into the thermoelastic nature of the AM NiTi builds. Characterization by DSC provides a comparative analysis for the investigating dependence of build, size, and spatial location of elementally blended Ti-rich AM parts on its TIMT. The advanced characterization is used for investigating any dependence of build, size, and spatial location on the thermoelastic nature of the AM builds. We look towards these observations to further advance the research on NiTi additive manufacturing, specifically on Ti-rich materials. An understanding of the TIMT behind Ti-rich NiTi SMAs can allow for production of AM builds having optimal SME properties for applications such as microactuators. Knowledge of the thermoelastic nature in Ti-rich AM NiTi SMAs allows for selection of AM builds with the narrowest hysteresis for pseudo elasticity-based applications.
Download or read book Shape Memory Alloys 2017 written by Takuo Sakon and published by MDPI. This book was released on 2018-03-15 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue Shape Memory Alloys 2017" that was published in Metals
Download or read book Shape Memory and Superelastic Alloys written by K Yamauchi and published by Elsevier. This book was released on 2011-04-30 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shape memory and superelastic alloys possess properties not present in ordinary metals meaning that they can be used for a variety of applications. Shape memory and superelastic alloys: Applications and technologies explores these applications discussing their key features and commercial performance. Readers will gain invaluable information and insight into the current and potential future applications of shape memory alloys.Part one covers the properties and processing of shape memory effect and superelasticity in alloys for practical users with chapters covering the basic characteristics of Ti-Ni-based and Ti-Nb-based shape memory and superelastic (SM/SE) alloys, the development and commercialisation of TiNi and Cu-based alloys, industrial processing and device elements, design of SMA coil springs for actuators before a final overview on the development of SM and SE applications. Part two introduces SMA application technologies with chapters investigating SMAs in electrical applications, hot-water supply, construction and housing, automobiles and railways and aerospace engineering before looking at the properties, processing and applications of Ferrous (Fe)-based SMAs. Part three focuses on the applications of superelastic alloys and explores their functions in the medical, telecommunications, clothing, sports and leisure industries. The appendix briefly describes the history and activity of the Association of Shape Memory Alloys (ASMA).With its distinguished editors and team of expert contributors, Shape memory and superelastic alloys: Applications and technologies is be a valuable reference tool for metallurgists as well as for designers, engineers and students involved in one of the many industries in which shape memory effect and superelasticity are used such as construction, automotive, medical, aerospace, telecommunications, water/heating, clothing, sports and leisure. - Explores important applications of shape memory and superelastic alloys discussing their key features and commercial performance - Assesses the properties and processing of shape memory effect and superelasticity in alloys for practical users with chapters covering the basic characteristics - Introduces SMA application technologies investigating SMAs in electrical applications, hot-water supply, construction and housing, automobiles and railways and aerospace engineering
Download or read book Precipitate Phases in Several High Temperature Shape Memory Alloys written by Fan Yang and published by . This book was released on 2012 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Initiated by the aerospace industry, there has been a great interest to develop high temperature shape memory alloys (HTSMAs) for actuator type of application at elevated temperatures. Several NiTi based ternary systems have been shown to be potential candidates for HTSMAs and this work focuses on one or more alloys in the TiNiPt, TiNiPd, NiTiHf, NiPdTiHf systems. The sheer scope of alloys of varying compositions across all four systems suggests that the questions raised and addressed in this work are just the tip of the iceberg. This work focuses on materials characterization and aims to investigate microstructural evolution of these alloys as a function of heat treatment. The information gained through the study can serve as guidance for future alloy processing. The emphasis of this work is to describe novel precipitate phases that are formed under aging in the ternary systems and one quaternary system. Employing conventional transmission electron microscopy (TEM), high resolution high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM), 3D atom probe tomography (3D APT), as well as ab initio calculations, the complete description of the unit cell for the new precipitates was determined. The methodology is summarized in the appendix to help elucidate some basics of such a process.
Download or read book Thermomechanical Training and Characterization of Ni Ti Hf and Ni Ti Hf Cu High Termperature Shape Memeory Alloys written by Chantz Michael Denowh and published by . This book was released on 2011 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel-Titanium (NiTi) is the most commonly used Shape Memory Alloy (SMA) for actuator applications. Typical SMA actuators use changes in temperature to initiate solid to solid phase transformations resulting in macroscopic material deformations; though NiTi is limited to temperature changes below 100°C. This eliminates high temperature applications of NiTi actuators. To expand the design window of SMAs, many high temperature NiTi based SMAs have been developed by adding ternary elements to the NiTi matrix. The additions result in degradation of the shape memory behaviors and their usefulness as actuators is still in question. The purpose of this research is to characterize and train two recently developed high temperature SMAs, NiTi 29.--Hf 20 and NiCu 5Ti 29.--Hf 20, to determine their effectiveness as linear actuators. Shape memory effect (SME) and superelastic tests were used to characterize the materials behavior followed by thermomechanical training at a constant stress. The SME test resulted in no martensite detwinning plateau and a non-linear stress-strain curve implying the simultaneous occurrence of slip and martensite reorientation. The superelastic tests also show an austenitic yield stress above 600 MPa. Thermomechanical training resulted in small amounts of plastic strain growth, and the development of two-way shape memory (TWSM). The TWSM results were fitted using the Bo & Lagoudas model, and is capable of predicting the actuation strains at other stresses. The results support the conclusion that hafnium distorts martensite slip planes, and (Ti, Hf) 2Ni and (Ti, Hf) 3Ni 4 precipitates form during aging and annealing. The distorted slip planes cause slip and martensite reorientation to occur simultaneously. This develops a strong stress field during training within the first few cycles. The stress field develops TWSM, but limits further plastic growth and TWSM development. The precipitate formation increases material strength, as seen in the superelastic loading, but also embrittles the material. Thermomechanical training of an annealed specimen resulted in a brittle failure after several thermal cycles due to the growth of particulate size during annealing. The two alloys are ideally suited for high temperature actuators. TWSM was trained into the material and the transformation temperatures are higher than that of NiTi, but low enough to avoid annealing and problematic creep temperatures.
Download or read book Structure and Properties of Ti Ni Au Shape Memory Alloys written by Todd M. Butler and published by . This book was released on 2013 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ternary Ti-Ni-X based alloys, where X = Pt, Pd, Hf, Au or Zr, show promise as high temperature shape memory alloys (HTSMAs). In comparison to binary Ni-Ti alloys, some hypo-stoichiometric versions of these ternary compositions exhibit higher transformation temperatures and better mechanical stability due to the formation of nano-scale precipitates. In this study, a Ti49Ni26Au25 (at.%) alloy was solution annealed at 1050°C for 3 hours and isothermally aged at 400°C and 550°C. A specimen was also annealed at 1050°C for 3 hours and furnace cooled. Ageing resulted in a very high peak micro-hardness for both temperatures. The structures and chemistries of the phases formed during ageing were characterized by wavelength dispersive x-ray spectroscopy (WDS), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), three-dimensional atom probe tomography (3DAP), x-ray diffraction (XRD), and differential scanning calorimetry (DSC). It was found that ageing at both 400°C and 550°C resulted in the formation of two different precipitates. First, two variants of a (Au, Ni)4Ti3 type phase form with SADPs similar to tetragonal D1a. The proposed orientation relationships with the matrix are the following: [001]D1a // [100]B2 with (011)B2 // (310)D1a and [00-1]D1a // [100]B2 with {011}B2 // (310)D1a . It is then postulated that the (Au, Ni)-rich phase creates local Ti-rich regions that promote the precipitation of two Ti2(Ni, Au) variants with tetragonal (I4/mmm) type symmetry. Their proposed orientation relationships with the matrix are the following: [100]Ti2(Ni, Au) // [100]B2 with (001)B2 // (001)Ti2(Ni. Au) and (001)B2 // (100)Ti2(Ni, Au). The combination of both phases appears to inhibit martensitic transformation by stabilizing the high temperature austenite phase, as evident by no transformation peaks in the aged specimens via DSC. However, it is interesting to note that the as-cast and 1050°C furnace cooled specimens did exhibit martensitic transformation with Ms values of approximately 135° and 160°C, respectively. Such behavior is thought to be attributed to their microstructure, which both appeared to consist mainly of (Au, Ni)4Ti3 platelets, as evident via SEM. This ultimately increases the Ti concentration in the matrix and raises the transformation temperatures. Two precipitate buttons with target compositions (at %) of 66.00 Ti - 3.50 Ni - 30.50 Au (Ti2(Ni, Au)) and 41.70 Ti - 27.40 Ni - 30.90 Au ((Au, Ni)4Ti3) were also heat treated at 550°C for 96 hours. The structures and chemistries of the phases formed during ageing were characterized by scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD. It was found that the as-cast Ti-rich button consisted of a Ti3Au phase and a Ti-Ni-Au B2 phase with small Ti-rich platelets, as evident via SEM. Ageing at 550°C for 96 hours promoted precipitate growth in the B2 regions. The crystallography of the additional Ti-rich platelets was found to fit well with I4/mmm symmetry, as evident via XRD. The as-cast (Au, Ni)-rich button consisted of a Au2Ti phase and a Ti-Ni-Au B2 phase with additional (Au, Ni)-rich platelets, as evident via SEM. Ageing at 550°C for 96 hours promoted the growth of the (Au, Ni)-rich platelets. The crystallography of the (Au, Ni)-rich platelets appeared to fit well with the proposed peak locations for (Au, Ni)4Ti3, as evident via XRD.
Download or read book CoNiGa High Temperature Shape Memory Alloys written by Ebubekir Dogan and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Shape memory alloys (SMAs) are an important class of smart materials that have the ability to remember a shape. Current practical uses of SMAs are limited to below 100°C which is the limit for the transformation temperatures of most commercially successful SMAs such as NiTi and Cu-based alloys. In recent years, the CoNiGa system has emerged as a new ferromagnetic shape memory alloy with some compositions exhibiting high martensitic transformation temperatures which makes CoNiGa a potential high temperature shape memory alloy (HTSMA). In this study, the microstructural evolution and martensitic transformation characteristics of CoNiGa (mainly Co46Ni2--Ga2-- and Co44Ni26Ga30 in at.%) HTSMAs were investigated in as-cast and hot-rolled conditions as a function of different heat treatments. Heat treatment conditions were selected to introduce single, two, and three phase structures, where two precipitate phases (ductile Y and hard Y') do not martensitically transform. Calorimetry, X-ray analysis, scanning and transmission electron microscopy, thermo-mechanical process and cycling techniques are applied to understand the structural and chemical factors influencing the thermal stability and transformation characteristics. The main findings include improvement of ductility, most cyclically stable compositions with narrow transformation hysteresis (
Download or read book Shape Memory Alloys Properties Technologies Opportunities written by Natalia Resnina and published by Trans Tech Publications Ltd. This book was released on 2015-03-23 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: The collective monograph consists of five parts: Theory and modeling of martensitic transformation and functional properties; Martensitic transformations and shape memory effects; Controlling the functional properties of shape memory alloys; Shape memory alloys with complex structure; Application of shape memory alloys) covering of all aspects of shape memory alloys from theory and modelling to applications. It presents the scientific results obtained by leading scientific teams studying shape memory alloys in the former Soviet Republics together with their colleagues from other countries during the last decade.
