Welding and Joining of NiTi Shape Memory Alloys: A Review
TL;DR: In this article, a detailed review of welding and joining processes applied to NiTi, in similar and dissimilar combinations considering both fusion and solid-state processes, is presented, and a special section is devoted to this technique.
About: This article is published in Progress in Materials Science.The article was published on 2017-07-01. It has received 211 citations till now. The article focuses on the topics: Welding & Friction welding.
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TL;DR: In this article, the effects of major process parameters on build quality (porosity, residual stress, and composition changes) and materials properties (microstructure and microsegregation) are reviewed.
398 citations
TL;DR: In this article, a unified equation to compute the energy density is proposed to compare works performed with distinct equipment and experimental conditions, covering the major process parameters: power, travel speed, heat source dimension, hatch distance, deposited layer thickness and material grain size.
369 citations
TL;DR: In this paper, a review of the control strategies for back support, weld thinning, and keyhole defects in friction stir welding (FSW) is presented, which are basically divided into self-supported FSW, non-weld-thinning FSW and friction stir-based remanufacturing.
350 citations
TL;DR: Electron beam welding is a fusion welding process and can be used for welding a wide variety of metals, such as stainless steel, Inconel, copper and other variations of their grades.
Abstract: Introduction Electron beam welding is a fusion welding process and can be used for welding a wide variety of metals, such as stainless steel, Inconel, copper and other variations of their grades. The metal thicknesses range from foils to thick metals sheets. In addition, two different metals or alloys can be welded together. E-beam welding has a vast variety of applications such as; electronics and packaging, automotive and aircraft industry, and in medical technology. In particular, down-hole tools for the oil and gas industry can be processed.
118 citations
19 Aug 2019-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a shape memory alloy (SMA) was manufactured by selective laser melting (SLM) under high enough energy inputs (155-292'J/mm 3 ).
Abstract: For additively manufactured components, it's widely accepted to have high enough energy input to facilitate nearly full density and low enough energy input to avoid cracking tendency. In this work, ultrahigh-performance Ti 50.6 Ni 49.4 (at.%) shape memory alloy (SMA) was manufactured by selective laser melting (SLM) under high enough energy inputs (155–292 J/mm 3 ). The microstructure, phase transformation behaviors, mechanical and shape memory properties of the SLM-manufactured SMA were investigated by various characterization methods of X-ray diffraction, scanning and transmission electron microscopies, differential scanning calorimetry, room temperature and stress-controlled cyclic tensile tests, etc. Results show that the martensite content and the austenite and martensitic transformation temperatures decrease with the decrease of laser energy input (the increase of laser scanning speed). Interestingly, the SLM-manufactured SMA exhibits ultrahigh tensile strength of 776 MPa and elongation of 7.2% under room-temperature tensile condition. In addition, stress-controlled cyclic tensile tests under 400 MPa indicate that the SLM-manufactured SMA has ultrahigh shape memory effect of 98.7% recovery ratio and 4.99% recoverable strain after ten times loading-unloading cycle. The ultrahigh mechanical and shape memory properties are associated to the combined effects of dispersedly distributed nano-sized Ti 2 Ni precipitates, ultrafine grains and profuse dislocations in the SLM-manufactured SMA. This work substantiates, for the first time, high enough energy input in SLM can be applied to manufacture ultrahigh-performance TiNi SMAs.
111 citations
References
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TL;DR: The study of mesenchymal stem cells, whether isolated from embryos or adults, provides the basis for the emergence of a new therapeutic technology of self‐cell repair.
4,861 citations
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30 Mar 2007TL;DR: Friction stir welding (FSW) is a relatively new solid-state joining process that is used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding as discussed by the authors.
Abstract: Friction stir welding (FSW) is a relatively new solid-state joining process. This joining technique is energy efficient, environment friendly, and versatile. In particular, it can be used to join high-strength aerospace aluminum alloys and other metallic alloys that are hard to weld by conventional fusion welding. FSW is considered to be the most significant development in metal joining in a decade. Recently, friction stir processing (FSP) was developed for microstructural modification of metallic materials. In this review article, the current state of understanding and development of the FSW and FSP are addressed. Particular emphasis has been given to: (a) mechanisms responsible for the formation of welds and microstructural refinement, and (b) effects of FSW/FSP parameters on resultant microstructure and final mechanical properties. While the bulk of the information is related to aluminum alloys, important results are now available for other metals and alloys. At this stage, the technology diffusion has significantly outpaced the fundamental understanding of microstructural evolution and microstructure–property relationships.
4,750 citations
Book•
01 Jan 1949
TL;DR: In this paper, the authors present an X-ray analysis of metallic materials and their properties, such as elastic properties, damping capacity and shape memory alloys, as well as their properties of metal and alloys.
Abstract: General physical and chemical constants X-ray analysis of metallic material Crystallography Crystal chemistry Metallurgically important minerals Thermochemical data Physical properties of molton salts Metallography Equilibrium diagrams Gas-metal systems Diffusion in metals General physical properties Elastic properties, damping capacity and shape memory alloys Temperature measurement and thermoelectric properties Radiating properties of metals Electron emission Electrical properties Magnetic materials and their properties Mechanical testing Mechanical properties of metals and alloys Sintered materials Lubricants Friction and wear Casting alloys and foundry data Engineering ceramics and refractory materials Fuels Heat treatment Metal cutting and forming Corrosion Electroplating and metal finishing Welding Soldering and brazing Vapour deposited coatings and thermal spraying Superplasticity Metal-matrix composites Non-conventional and emerging metallic minerals modelling and simulation supporting technologies for the processing of metals and alloys.
3,593 citations
TL;DR: The bone marrow contains multipotent MSC, which can be easily isolated and cultured in vitro, and the possibility of their clinical use in cell and gene therapy is analyzed.
Abstract: Institute of Biological Medicine, Moscow The formation of the concept of a mesenchymal stem cell (MSC) is a priority of Russian biological science. A. Ya. Fridenshtein and his colleagues were the first who experimentally proved the existence of MSC. Osteogenic potential of fibroblastlike bone marrow cells of different mammalian species was demonstrated [25,26]. Fibroblast-like bone marrow cells often formed discrete adhesive colonies in vitro [27,28,47]. After heteroand orthotopic transplantation in vivo cloned cells from these colonies formed bone, cartilaginous, fibrous, and adipose tissues [48]. Intensive self-renewal and multipotency of fibroblast-like colony-forming cells from the bone marrow allowed Fridenshtein and Owen to formulate a concept of multipotent mesenchymal precursor cells (MPC) [62]. An ordered chain of finely regulated cell proliferation, migration, differentiation, and maturation processes underlies the formation of the majority of cell lineages in adult organisms. The earliest cell elements in this chain are stem cells (SC). Along with extensive self-renewal capacity, SC possess a great differentiation potential. Apart from well studied hemopoietic and intestinal SC, other SC classes were recently discovered in adult organism. Until recently it was considered that SC in adults can give rise to cell lines specific to tissues where these cells are located; however, new facts necessitated revision of this concept. Hemopoietic SC capable of differentiating into all cell elements of the blood, can also be a source of hepatic oval cells [65]; neural SC, precursors of neurons and glia [2,3], serve as the source of early and committed hemopoietic precursors [10]. MSC, a source of bone, cartilaginous, and adipose tissue cells, can differentiate into neural cells [46]. Tissue growth and reparation are associated with migration of uncommitted precursor cells from other tissues. During muscle tissue reparation mesenchymal SC migrate from the bone marrow into skeletal muscles [24]. Hence, in addition to capacity to unlimited division and reproduction of a wide spectrum of descendants of a certain differentiation line, adult SC are characterized by high plasticity. The existence of a rare type of somatic pluripotent SC, common precursors of all SC in an adult organism, is hypothesized [79]. Another important characteristic of SC is their migration from the tissue niche into circulation, which was experimentally proven for hemopoietic and MSC [69,73]. For activation of the differentiation program, circulating SC should get into an appropriate microenvironment [75,78]. A potent stimulus for investigation of SC is the possibility of their clinical use in cell and gene therapy. The bone marrow contains multipotent MSC, which can be easily isolated and cultured in vitro. It is therefore interesting to analyze some fundamental aspects of MSC biology and the possibilities of their clinical use. MSC descendants are involved in the formation of bones, cartilages, tendons, adipose and muscle tissues, and stroma maintaining the hemopoiesis [12,19,51]. The term MPC is used to denote MSC and their committed descendants capable of differentiating into at least two types of mature cells, which are present in the bone marrow and some mesenchymal tissues [16,19,57,82].
3,582 citations
"Welding and Joining of NiTi Shape M..." refers background in this paper
...In this study, the response of mesenchymal stem cells [247] on the effects induced by laser welding on the material (surface roughness, topography and Ti/Ni ratio) were evaluated....
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TL;DR: In this article, a selfconsistent and logical account of key issues on Ti-Ni-based alloys from physical metallurgy viewpoint on an up-to-date basis is presented.
3,484 citations
"Welding and Joining of NiTi Shape M..." refers background or result in this paper
...For Ni-rich NiTi, the heat treatments promote a raise in the transformation temperatures, due to Ni depletion of the matrix surrounding the Ni-rich precipitates [2]....
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...For Ni-rich alloys, the dependence of the transformation temperatures on the composition is more significant than for Ti-rich NiTi, which is related with the solubility range on the Ti-rich side of the Ni-Ti phase diagram [2]....
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...Among these alloys, NiTi is the most important one, not only because of its functional properties, but also because it presents high strength and ductility [2]....
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...However, since the transformation temperatures of NiTi are also dependent on the alloying elements [2], the use of a filler material can be interesting to tune the transformation temperatures of the welded joints and their mechanical response....
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...In fact, Ni depletion increases the transformation temperatures [2]....
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