The Effect of Low-Angle and High-Angle Grain Boundaries on Elevated Temperature Strength

1994 ◽  
Vol 362 ◽  
Author(s):  
M. E. Kassner
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Large Angle ◽  
High Angle ◽  
Elevated Temperature Strength ◽  
Ambient Temperatures ◽  
The Past ◽  
Creep Regime ◽  
New Evidence ◽  
General Opinion

AbstractThe influence of small (subgrain) misorientation interfaces on the mechanical behavior of metals and alloys deforming within the creep regime has been intensively studied over the past several decades. Controversies have existed, but some new experiments suggest, contrary to the general opinion, that low-angle boundaries are not associated with the rate controlling process for plasticity and do not affect strength. The new evidence will be discussed in terms of other established experimental trends. Large-angle boundaries may have a smaller effect on elevated temperature strength than at ambient temperatures and do not appear to dramatically affect elevated temperature strength. Superplastic effects are not addressed.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Atomic Imaging of Crystals using Large-Angle Electron Scattering in STEM

1990 ◽  
Vol 48 (1) ◽  
pp. 74-75
Author(s):  
D.E. Jesson ◽  
S. J. Pennycook
Keyword(s):  
Wave Function ◽  
Electron Scattering ◽  
Numerical Solutions ◽  
Large Angle ◽  
Real Space ◽  
High Angle ◽  
Analytical Treatment ◽  
Order Zero ◽  
Experimental Conditions ◽  
Ewald Sphere

It is well known that conventional atomic resolution electron microscopy is a coherent imaging process best interpreted in reciprocal space using contrast transfer function theory. This is because the equivalent real space interpretation involving a convolution between the exit face wave function and the instrumental response is difficult to visualize. Furthermore, the crystal wave function is not simply related to the projected crystal potential, except under a very restrictive set of experimental conditions, making image simulation an essential part of image interpretation. In this paper we present a different conceptual approach to the atomic imaging of crystals based on incoherent imaging theory. Using a real-space analysis of electron scattering to a high-angle annular detector, it is shown how the STEM imaging process can be partitioned into components parallel and perpendicular to the relevant low index zone-axis.It has become customary to describe STEM imaging using the analytical treatment developed by Cowley. However, the convenient assumption of a phase object (which neglects the curvature of the Ewald sphere) fails rapidly for large scattering angles, even in very thin crystals. Thus, to avoid unpredictive numerical solutions, it would seem more appropriate to apply pseudo-kinematic theory to the treatment of the weak high angle signal. Diffraction to medium order zero-layer reflections is most important compared with thermal diffuse scattering in very thin crystals (<5nm). The electron wave function ψ(R,z) at a depth z and transverse coordinate R due to a phase aberrated surface probe function P(R-RO) located at RO is then well described by the channeling approximation;

scholarly journals Emergency management of the paediatric patient with convulsive status epilepticus

2021 ◽  
Vol 26 (1) ◽  
pp. 50-57
Author(s):  
Kyle C McKenzie ◽  
Cecil D Hahn ◽  
Jeremy N Friedman
Keyword(s):  
Clinical Practice ◽  
Status Epilepticus ◽  
Emergency Management ◽  
Treatment Algorithm ◽  
Position Statement ◽  
Convulsive Status Epilepticus ◽  
Pharmacological Management ◽  
The Past ◽  
New Treatment ◽  
New Evidence

Abstract This guideline addresses the emergency management of convulsive status epilepticus (CSE) in children and infants older than 1 month of age. It replaces a previous position statement from 2011, and includes a new treatment algorithm and table of recommended medications based on new evidence and reflecting the evolution of clinical practice over the past several years. This statement emphasizes the importance of timely pharmacological management of CSE, and includes some guidance for diagnostic approach and supportive care.

Mathematical Issues Arising From the Directed Mutation Controversy

Genetics ◽  
2003 ◽  
Vol 164 (1) ◽  
pp. 373-379
Author(s):  
Qi Zheng
Keyword(s):  
Mathematical Reasoning ◽  
Large Body ◽  
Directed Mutation ◽  
The Past ◽  
New Evidence

Abstract During the past 14 years or so a large body of new evidence that supposedly supports the directed mutation hypothesis has accumulated. Interpretation of some of the evidence depends on mathematical reasoning, which can be subtler than it appears at first sight. This article attempts to clarify some of the mathematical issues arising from the directed mutation controversy, thereby offering alternative interpretations of some of the evidence.

Top resources and tools for physician management of chronic pain in the Canadian Armed Forces

2021 ◽  
pp. e20210039
Author(s):  
Paul Dhillon ◽  
Nickie Mathew ◽  
Richard Lee ◽  
Eric Juneau ◽  
Robert Dale ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Armed Forces ◽  
Continuous Medical Education ◽  
Prescription Practices ◽  
The Past ◽  
Canadian Armed Forces ◽  
Busy Clinician ◽  
Primary Care Clinicians ◽  
Canadian Military ◽  
New Evidence

LAY SUMMARY Diagnosis and management of chronic pain in Canada by primary care clinicians is a challenging and changing field with new approaches, evidence, and tools emerging in the past few years. For a busy clinician, it is vital to integrate and become aware of new tools that can improve the care delivered to patients. This article summarizes new evidence-based tools, key guidelines and research, algorithms, and simplified prescription practices, in addition to continuous medical education resources that will allow busy clinicians to rapidly be brought up to speed on the latest in chronic pain management in the Canadian military context.

scholarly journals Enhancing elevated temperature strength of copper containing aluminium alloys by forming L12 Al3Zr precipitates and nucleating θ″ precipitates on them

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Surendra Kumar Makineni ◽  
Sandeep Sugathan ◽  
Subhashish Meher ◽  
Rajarshi Banerjee ◽  
Saswata Bhattacharya ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Aluminium Alloys ◽  
Elevated Temperature Strength

scholarly journals Examining plant-parasitoid interactions in tritrophic systems

2000 ◽  
Vol 29 (2) ◽  
pp. 189-203 ◽  
Author(s):  
Consuelo M. De Moraes ◽  
W. J. Lewis ◽  
James H. Tumlinson
Keyword(s):  
Volatile Compounds ◽  
Plant Tissues ◽  
Specific Information ◽  
Systemic Response ◽  
The Past ◽  
Entire Plant ◽  
Recent Developments ◽  
Herbivore Species ◽  
Herbivore Induced Plant Volatiles ◽  
New Evidence

The demonstration that parasitoids are attracted to volatile compounds released by plants in response to herbivore feeding has generated a great deal of interest over the past ten years. The release of volatile signals by plants occurs not only in response to tissue damage but is also specifically initiated by exposure to herbivore salivary secretions. Although some volatile compounds are stored in plant tissues and immediately released when damage occurs, others are induced by herbivore feeding and released not only from damaged tissue but also from undamaged leaves. Thus, damage localized to only a few leaves results in a systemic response and the release of volatiles from the entire plant. New evidence suggests that, in addition to being highly detectable and reliable indicators of herbivore presence, herbivore-induced plant volatiles may convey herbivore-specific information that allows parasitoids to discriminate even closely-related herbivore species at long range. Here we give an overview of the recent developments in the investigation of plant-parasitoid interactions.

Microstructure, excess solid solubility, and elevated-temperature mechanical behavior of spray-atomized and codeposited Al-Ti-SiCP

1992 ◽  
Vol 23 (6) ◽  
pp. 719-736 ◽  
Author(s):  
M. Gupta ◽  
J. Juarez-Islas ◽  
W. E. Frazier ◽  
F. A. Mohamed ◽  
E. J. Lavernia
Keyword(s):  
Elevated Temperature ◽  
Mechanical Behavior ◽  
Solid Solubility
Sign in / Sign up

Export Citation Format

Share Document