scholarly journals Erratum: “Changes in State Variables at Elevated Temperatures” (Journal of Engineering Materials and Technology, 1989, 111, pp. 192–203)

1989 ◽  
Vol 111 (4) ◽  
pp. 337-337
Author(s):  
H. Sehitoglu
Keyword(s):  
Elevated Temperatures ◽  
State Variables ◽  
Engineering Materials

Paper 10: Titanium, Beryllium, and the Refractory Metals in the Aircraft Industry

1965 ◽  
Vol 180 (4) ◽  
pp. 75-89
Author(s):  
A. R. G. Brown ◽  
K. S. Jepson
Keyword(s):  
Elevated Temperatures ◽  
Refractory Metals ◽  
Aircraft Industry ◽  
New Materials ◽  
Engineering Materials

The need for new materials capable of operating at elevated temperatures often while severely stressed is outlined, and the properties of titanium, beryllium and the refractory metals which give them importance for such application are described. These are ‘new’ metals in that their application as engineering materials is in its infancy and, as yet, generally accepted alloys have not been developed. The difficulties in forming and joining the metals are discussed, and their characteristic properties which make utilization difficult are outlined. Finally, a brief survey is made of the properties obtainable in alloys of the metals described and potential and actual fields of application are discussed.

Measurement of the Damping of Engineering Materials During Flexural Vibration at Elevated Temperatures

1944 ◽  
Vol 11 (2) ◽  
pp. A86-A92
Author(s):  
Carl Schabtach ◽  
R. O. Fehr
Keyword(s):  
Strain Gage ◽  
Modulus Of Elasticity ◽  
Tuning Fork ◽  
Elevated Temperatures ◽  
Flexural Vibration ◽  
Logarithmic Decrement ◽  
Vibration Frequencies ◽  
Bending Stresses ◽  
Engineering Materials

Abstract The method and equipment developed and used by the authors for measuring the damping of materials are described. A tuning-fork specimen is set into vibration by jerking a spreader from the gap between the ends of the tines. The damping is expressed in terms of the logarithmic decrement of the decaying vibration, which is measured and recorded by means of a magnetic oscillograph, amplifiers, and a resistance-type electric strain gage cemented to the specimen. The results include (1) the damping of a number of materials during flexural vibration at approximately 1000 cycles per sec, at maximum bending stresses up to 40,000 psi, and at temperatures up to 1400 F; (2) the variation in modulus of elasticity with temperature, as determined from the specimen vibration frequencies.

Changes in State Variables at Elevated Temperatures

1989 ◽  
Vol 111 (2) ◽  
pp. 192-203 ◽  
Author(s):  
Huseyin Sehitoglu
Keyword(s):  
Cyclic Deformation ◽  
Strain Aging ◽  
Elevated Temperatures ◽  
High Strain ◽  
Back Stress ◽  
Internal Stresses ◽  
Strain Rates ◽  
Multiaxial Loading ◽  
State Variables ◽  
Different Temperatures

Two state variables, strength and internal (back) stress, were determined during cyclic deformation by rapid unloading-reloading experiments. The experiments were performed at different temperatures and strain rates, Considerable increases in strength at low temperatures (20°C–300°C) due to cyclic deformation and due to strain aging were measured. The variation of internal stresses at elevated temperatures (600°C) with strain rate was identified. Regions of high back stress rates were established on stress-back stress diagrams. High strain rates during unload-reload excursions are needed to minimize changes in back stress during measurements. The results (state variables) and the stress-strain response were compared to predictions based on a unified constitutive model. The capabilities of the model under cyclic loading, decrease in strength at high temperatures due to spheroidization, and increase in strength due to strain aging at lower temperatures, were found to be satisfactory. The extension of the unloading-reloading technique to multiaxial loading is outlined.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

Sign in / Sign up

Export Citation Format

Share Document