Theory of high temperature intercrystalline fracture under static or fatigue loads, with or without irradiation damage

1974 ◽  
Vol 5 (8) ◽  
pp. 1743-1751 ◽  
Author(s):  
Johannes Weertman
Keyword(s):  
High Temperature ◽  
Irradiation Damage ◽  
Intercrystalline Fracture ◽  
Fatigue Loads

Probabilistic Design of High Temperature Components Subjected to Low Cycle Fatigue Loads

1995 ◽  
Author(s):  
Ronald Pigott
Keyword(s):  
High Temperature ◽  
Factor Of Safety ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Probabilistic Design ◽  
Cycle Fatigue ◽  
Single Factor ◽  
First Order Second Moment ◽  
Fatigue Loads ◽  
High Temperature Components

Abstract From the beginning, engineers have focused on the special case of determinism in the design process, and an enormous methodology has been developed to support this approach. Today, however, customers are demanding greater reliability and are imposing greater penalties for failure. In order to achieve higher reliability, and in order to asses risk of failure, probabilistic approaches will almost certainly have to be employed. While designers have always used probability in their work, it has usually been done with risk represented in a single factor of safety. This paper focuses on the application of probability theory to the design of high temperature components which are subjected to low cycle fatigue loads. Creep low cycle fatigue interaction and probabilistic design are both complex subjects. In order to make the probabilistic design of components subjected to creep and low cycle fatigue tractable, the calculation models must be as simple as possible without sacrificing too much on accuracy. In this paper, cumulative damage is determined using Miner’s Rule in conjunction with “range pair” cycle counting. The effect of operation at elevated temperatures is included using Coffin’s frequency modified approach. A first order second moment (FORM) method for including probabilistic effects is developed and some sample calculations are presented. It is shown that the traditional deterministic approach using a single factor of safety does not provide a uniform margin of safety for all design conditions.

High temperature effects on irradiation damage of Ti 2 AlC

2017 ◽  
Vol 406 ◽  
pp. 662-669 ◽  
Author(s):  
Shaoshuai Liu ◽  
Chenxu Wang ◽  
Tengfei Yang ◽  
Yuan Fang ◽  
Qing Huang ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Effects ◽  
Irradiation Damage

scholarly journals The absence of metamictisation in natural monazite

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Lutz Nasdala ◽  
Shavkat Akhmadaliev ◽  
Boris E. Burakov ◽  
Chutimun Chanmuang N ◽  
Radek Škoda
Keyword(s):  
High Temperature ◽  
Radioactive Waste ◽  
Radiation Damage ◽  
Alpha Particle ◽  
Annealing Temperature ◽  
Irradiation Damage ◽  
Alpha Radiation ◽  
Structural Restoration ◽  
Damage State ◽  
Damage Level

Abstract The actinide-containing mineral monazite–(Ce) is a common accessory rock component that bears petrogenetic information, is widely used in geochronology and thermochronology, and is considered as potential host material for immobilisation of radioactive waste. Natural samples of this mineral show merely moderate degrees of radiation damage, despite having sustained high self-irradiation induced by the decay of Th and U (for the sample studied herein 8.9 ± 0.3 × 1019 α/g). This is assigned to low damage-annealing temperature of monazite–(Ce) and “alpha-particle-assisted reconstitution”. Here we show that the response of monazite–(Ce) to alpha radiation changes dramatically, depending on the damage state. Only in radiation-damaged monazite–(Ce), 4He ions cause gradual structural restoration. In contrast, its high-temperature annealed (i.e. well crystalline) analogue and synthetic CePO4 experience He-irradiation damage. Alpha-assisted annealing contributes to preventing irradiation-induced amorphisation (“metamictisation”) of monazite–(Ce); however, this process is only significant above a certain damage level.

614 Effect of Irradiation Damage on Hardness of Tungsten and Copper Joint Materials at High Temperature

2012 ◽  
Vol 2012.20 (0) ◽  
pp. 165-166
Author(s):  
Takayuki Obuki ◽  
Akira Kurumada ◽  
Goroh Itoh ◽  
Hideo Watanabe ◽  
Akira Matsuo
Keyword(s):  
High Temperature ◽  
Irradiation Damage

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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