Download or read book An Investigation for Fracture Toughness and Creep Behavior in Carbon Doped Nanocrystalline Nickel written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrodeposited nanocrystalline nickel that exhibits extraordinary high strength would be a promising candidate for a structural material. The potential engineering applications of nanocrystalline materials need more detailed study on deformation and fracture toughness at room and elevated temperatures under tensile loading. Fracture toughness and creep deformation of nanocrystalline Ni, Ni-C, and Ni-B studied under the course of this research. The results have been published in four (4) papers in refereed journals and have been presented in several international symposiums. One additional manuscript has been submitted recently for publication. Tensile behavior and fracture in nickel and carbon doped nanocrystalline nickel, Creep behavior of nanocrystalline nickel at 290 and 373 K, Creep in boron-doped nanocrystalline nickel, R-Curve characterization of the fracture toughness of nanocrystalline nickel thin sheets, Effect of interstitials on tensile strength and creep in nanostructured Ni.

Download or read book Fracture Behavior of Advanced Structural Materials written by Joseph Aaron Lemberg and published by . This book was released on 2011 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Further development of ultra-high structural applications requires new materials that can withstand the extreme environments found in power-generation turbines. Highly refractory materials capable of high strength at temperatures in excess of 1100°C are either inherently brittle (Al2O3, Si3N4) or cannot survive at such temperatures in oxidizing atmospheres (Mo, Nb). Brittle materials may be toughened with the addition of a more ductile phase. Materials that do not form protective oxide layers can be alloyed with Si to form more protective silicate scales. A problem still remains as to how dissimilar materials like Al2O3 and Si3N4 can be joined. A brief discussion of the fracture behavior of ductile-phase-toughened nanocrystalline Al2O3 and functionally-graded material joints of Al2O3 and Si3N4 will precede an in-depth exploration of fracture in two Mo-Si-B intermetallic alloys. Al2O3-based nanocomposites were fabricated and consolidated via spark plasma sintering. The influence on the fracture behavior of nanocrystalline Al2O3 of single-walled carbon nanotube (SWCNT) and Nb additions were examined by in-situ bend testing within a scanning electron microscope. The addition of 10 vol.% Nb to nanocrystalline Al2O3 provided substantial improvement of fracture toughness (6.1MPa-m1/2)--almost three times that of unalloyed nanocrystalline Al2O3. Observation of cracks emanating from Vickers indents, as well as bend specimen fracture surfaces, reveal the operation of ductile phase toughening in the Nb-Al2O3 nanocomposites. Further addition of 5 vol.% SWCNTs to the 10 vol.% Nb-Al2O3 revealed a more porous structure and less impressive fracture toughness. The SWCNTs, initially added to form uncracked ligament bridges spanning the crack which would carry load and shield the crack tip from the full extent of the remotely-applied load, acted as crack initiation sites and overwhelmed any toughness gains afforded by the ductile Nb grains. Nominally crack-free Al2O3- Si3N4 joints, comprised of 15 layers of gradually differing compositions of Al2O3/Si3N4, have been fabricated using SiAlON polytypoids as functionally graded materials (FGM) bonding layers for high-temperature applications. Using flexural strength tests conducted both at room and at elevated temperatures, the average fracture strength at room temperature was found to be 437 MPa; significantly, this value was unchanged at temperatures up to 1000°C. Scanning electron microscopy (SEM) observations of fracture surfaces indicated the absence of any glassy phase at the triple points. This result was quite contrary to the previously reported 20-layer Al2O3/Si3N4 FGM samples where three-point bend testing revealed severe strength degradation at high temperatures. Consequently, the joining of Al2O3 to Si3N4 using functional gradients of SiAlON polytypoids can markedly improve the suitability of these joints for high-temperature applications. New alloys based on borosilicides of molybdenum have been considered as potential replacements for current Ni-base superalloys, as they show promise as highly oxidation- and creep-resistant materials while still maintaining a moderate level of damage tolerance. Two alloys, each composed of Mo-3Si-1B (wt.%) with nominally similar fine-grained microstructures, have been developed utilizing markedly differing processing routes. Here, we study the influence of processing route on the fracture toughness of alloys containing ~55 vol.% ductile [alpha]-Mo and ~45 vol.% brittle intermetallics (Mo3Si and Mo5SiB2 (T2)). The room-temperature toughness of these two alloys is significantly lower than that previously evaluated coarser-grained Mo-Si-B alloys with similar composition; however at 1300°C, the crack-initiation toughness of the fine- and coarse-grained alloys are nearly identical. At lower temperatures, the current finer-grained materials behave in a brittle manner as the smaller grains do not provide much impediment to crack extension; cracks can advance with minimal deflection thereby limiting any extrinsic toughening. Plastic constraint of ductile [alpha]-Mo grains from the hard intermetallic grains also serves to lower the toughness. At 1300°C, the increased ductility of [alpha]-Mo allows for significant plasticity; the correspondingly much larger contribution from intrinsic toughening results in significantly enhanced toughness, such that the finer grain morphology becomes less important in limiting crack-growth resistance. Optimization of these alloys is still required, however, to tailor their microstructures for the mutually-exclusive requirements of oxidation resistance, creep resistance and damage tolerance.

Download or read book Metals Abstracts written by and published by . This book was released on 1998 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Toughness and Related Characteristics of the Cryogenic Nickel Steels written by Alan W. Pense and published by . This book was released on 1975 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metals Abstracts Index written by and published by . This book was released on 1996 with total page 1622 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 1556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metallurgical Transactions written by and published by . This book was released on 1990 with total page 1148 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Engineered Materials Abstracts written by and published by . This book was released on 1995-07 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Engineering Index Annual written by and published by . This book was released on 1992 with total page 2264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since its creation in 1884, Engineering Index has covered virtually every major engineering innovation from around the world. It serves as the historical record of virtually every major engineering innovation of the 20th century. Recent content is a vital resource for current awareness, new production information, technological forecasting and competitive intelligence. The world?s most comprehensive interdisciplinary engineering database, Engineering Index contains over 10.7 million records. Each year, over 500,000 new abstracts are added from over 5,000 scholarly journals, trade magazines, and conference proceedings. Coverage spans over 175 engineering disciplines from over 80 countries. Updated weekly.

Download or read book Ceramic Abstracts written by and published by . This book was released on 1998 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ceramics Technology written by and published by . This book was released on 1996 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ceramic Nanocomposites written by Rajat Banerjee and published by Elsevier. This book was released on 2013-07-31 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ceramic nanocomposites have been found to have improved hardness, strength, toughness and creep resistance compared to conventional ceramic matrix composites. Ceramic nanocomposites reviews the structure and properties of these nanocomposites as well as manufacturing and applications.Part one looks at the properties of different ceramic nanocomposites, including thermal shock resistance, flame retardancy, magnetic and optical properties as well as failure mechanisms. Part two deals with the different types of ceramic nanocomposites, including the use of ceramic particles in metal matrix composites, carbon nanotube-reinforced glass-ceramic matrix composites, high temperature superconducting ceramic nanocomposites and ceramic particle nanofluids. Part three details the processing of nanocomposites, including the mechanochemical synthesis of metallic–ceramic composite powders, sintering of ultrafine and nanosized ceramic and metallic particles and the surface treatment of carbon nanotubes using plasma technology. Part four explores the applications of ceramic nanocomposites in such areas as energy production and the biomedical field.With its distinguished editors and international team of expert contributors, Ceramic nanocomposites is a technical guide for professionals requiring knowledge of ceramic nanocomposites, and will also offer a deeper understanding of the subject for researchers and engineers within any field dealing with these materials. - Reviews the structure and properties of ceramic nanocomposites as well as their manufacturing and applications - Examines properties of different ceramic nanocomposites, as well as failure mechanisms - Details the processing of nanocomposites and explores the applications of ceramic nanocomposites in areas such as energy production and the biomedical field

Download or read book Tungsten written by Erik Lassner and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Why does someone write a book about Tungsten? There are several reasons and precedents for this, the most important of which is that the last book on tungsten was written more than 20 years ago, in 1977, by St. W H. Yih and Ch T. Wang. During the intervening period there have been many new scientific and technological developments and innova tions, so it was not only our opinion but the view of many other members of the "tungsten family" that it was time to start writing a new book about tungsten. Preparations of the new book began in 1994. further impetus to the project was provided by the realization that in spite of this new knowledge having been presented at seminars or published in the technical press, a general acknowledgement of it by the majority of technicians and scientists is still far from being realized. It is our hope that this book will significantly contribute to a broader acceptance of recent scientific and technological innovations. An important prerequisite for such a project is the availability of a recently retired, experienced person willing to devote his time and talents to the tedious part of the exercise.