The Role of Grain Boundary Chemistry and the Environment on Intergranular Fracture PDF Download
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Author: R. M. Latanision
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
In this discussion the influence of grain boundary segregates and their interaction with the environment will be discussed with particular reference to hydrogen-induced intergranular embrittlement. Many of the elements which are found segregated at grain boundaries (i.e., the metalloid elements) are catalyst poisons for the hydrogen evolution reaction in electrolytes and, hence, stimulate hydrogen absorption. The use of glassy metal alloys (transition metal-metalloid type) as grain boundary analogs in studying hydrogen absorption and permeation is explored. Likewise, permeation experiments which distinguish between lattice, grain boundary and dislocation transport mechanisms will be discussed. (Author).
Author: R. M. Latanision
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Book Description
In this discussion the influence of grain boundary segregates and their interaction with the environment will be discussed with particular reference to hydrogen-induced intergranular embrittlement. Many of the elements which are found segregated at grain boundaries (i.e., the metalloid elements) are catalyst poisons for the hydrogen evolution reaction in electrolytes and, hence, stimulate hydrogen absorption. The use of glassy metal alloys (transition metal-metalloid type) as grain boundary analogs in studying hydrogen absorption and permeation is explored. Likewise, permeation experiments which distinguish between lattice, grain boundary and dislocation transport mechanisms will be discussed. (Author).
Author: G. Was
Publisher: Trans Tech Publications Ltd
ISBN: 3035704414
Category : Technology & Engineering
Languages : en
Pages : 374
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Book Description
Materials Science Forum Vol. 46
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 8
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Book Description
Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K{sub ISCC}, crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.
![The Role of Grain Boundary Chemistry and Structure in the Environmentally-assisted Intergranular Cracking of Nickel-base Alloys. Progress Report, [December 1, 1990--November 31, 1993]. PDF](https://books.google.com/books/content/images/frontcover/6_20DAEACAAJ?fife=w80-h100)
Author:
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Category :
Languages : en
Pages :
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Progress focused on (1) determination of the role of C and Cr on deformation and IG cracking behavior of Ni-(5--30)Cr-9Fe, (2) determination of the effect of grain boundary misorientation on IG cracking behavior, (3) construction of an electron backscattering pattern (EBSP) imaging system, (4) determination of effect of the environment on creep and cracking, and (5) characterization of the surface film. Results showed that both C and Cr are potent solid solution strengtheners which can reduce the steady state creep rate at 360[degree]C by several orders of magnitude. Intergranular cracking of 100 [mu]m grain samples of high purity Ni-16Cr-9Fe at 360[degree]C occurs by formation of grain boundary voids and interlinkage, driven by dislocation creep in the matrix. Creep experiments in primary water at 360[degree]C and an applied cathodic potential show that the creep rate is increased by an order of magnitude over that in Ar and the percent IG fracture increases as well. Oxide film composition and thickness is a sensitive function of the C content, increasing in thickness and Ni(OH)[sub 2] content with increase in C or decrease in Cr to 5 wt%. Thermomechanical treatments along with electron channeling pattern (ECP) analysis wee used to create and index, samples with enhanced fractions of coincident site lattice boundaries (CSLBs). Constant extension rate tensile (CERT) experiments on samples with a high percentage of CSLBs showed IG cracking compared with general high angle boundaries. However, these experiments were conducted on grain sizes of 300 [mu]m, while commercial material is an order of magnitude smaller. An electron backscattering pattern imaging system has been constructed for an environmental scanning electron microscope which can image grains below [mu]m. The system has been successfully benchmarked against results from ECP analysis.
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Category : Aeronautics
Languages : en
Pages : 702
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Book Description
Author: R.M. Latanision
Publisher: Springer Science & Business Media
ISBN: 9400936656
Category : Technology & Engineering
Languages : en
Pages : 726
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Book Description
For many years it has been recognized that engineering materials that are-tough and ductile can be rendered susceptible to premature fracture through their reaction with the environment. Over 100 years ago, Reynolds associated hydrogen with detrimental effects on the ductility of iron. The "season cracking" of brass has been a known problem for dec ades, but the mechanisms for this stress-corrosion process are only today being elucidated. In more recent times, the mechanical properties of most engineering materials have been shown to be adversely affected by hydrogen embrittlement or stress-corrosion cracking. Early studies of environmental effects on crack growth attempted to identify a unified theory to explain the crack growth behavior of groups of materials in a variety of environments. It is currently understood that there are numerous stress-corrosion processes some of which may be common to several materials, but that the crack growth behavior of a given material is dependent on microstructure, microchemistry, mechanics, surface chemistry, and solution chemistry. Although the mechanism by which various chemical species in the environment may cause cracks to propagate in some materials but not in others is very complex, the net result of all environmentally induced fracture is the reduction in the force and energy associated with the tensile or shear separation of atoms at the crack tip.
Author: L. Pietronero
Publisher: Elsevier
ISBN: 0444598413
Category : Science
Languages : en
Pages : 489
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Book Description
Fractals in Physics
Author: Shanthi Subramanian
Publisher:
ISBN:
Category :
Languages : en
Pages : 308
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Book Description
Author: Pavel Lejcek
Publisher: Springer Science & Business Media
ISBN: 3642125050
Category : Technology & Engineering
Languages : en
Pages : 249
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Book Description
Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Book Description
Brittle intergranular fracture occurs when impurity elements segregate to the grain boundaries of a material and lower their cohesive strength. Although many embrittling elements have been identified by experimental studies, the reason why these elements cause embrittlement has remained elusive. This paper presents results of fully quantum mechanical cluster calculations which address this question. It will be shown that strong embrittling elements draw charge from the neighboring metal atoms onto themselves. They thus remove charge from the metal-metal bonds which hold the grain boundary together and weaken them. Cohesive enhancers do not draw charge off the metal atoms and thus do not weaken the metal-metal bond network. In addition, they form rather homopolar bonds with the metal atoms and thus provide an added increment of bonding in the grain boundary.
