scholarly journals Creep and Material Design

2012 ◽  
Vol 9 (1) ◽  
pp. 169-171
Author(s):  
Ram Oruganti
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Room Temperature ◽  
Shape Change ◽  
Creep Damage ◽  
Material Design ◽  
The Other ◽  
Permanent Shape ◽  
Total Life

When a material is subjected to temperature and stress, it deforms slowly resulting in permanent shape change. If the same amount of stress were applied at room temperature, the material would not budge. This deformation at high temperature under low stresses is called creep. This phenomenon is important for OEM’S like GE etc. since turbine components are exposed to low stress and high temperature and the resulting shape change is not a desirable consequence. Apart from the change in shape, the components can eventually rupture leading to catastrophic consequences. So it is imperative that the nature of this phenomenon is understood well. Some of the questions to be answered are 1) What makes one material more resistant to creep that the other 2) How can a material’s creep resistance be improved 3) How can the current creep damage in a component be measured 4) Is it possible to say what fraction of the total life of a component has been consumed by creep.

ARSENIDES OF THE TRANSITION METALS: II. THE NICKEL ARSENIDES

1957 ◽  
Vol 35 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
R. D. Heyding ◽  
L. D. Calvert
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Transition Metals ◽  
Stability Region ◽  
Room Temperature ◽  
Metastable Phase ◽  
The Other ◽  
Incongruent Melting ◽  
Diffraction Patterns ◽  
The Stability

Alloys of nickel and arsenic containing up to 60% As by weight have been studied by means of room temperature and high temperature Debye-Scherrer diagrams. Three compounds have been identified: Ni5As2, Ni12−xAs8 (maucherite), and NiAs (niccolite). The first of these is homogeneous from Ni5As2 to Ni4.8A2 at room temperature, and to Ni4.6As2 above 250 °C., while the latter is homogeneous from NiAs to Ni0.95As. Contrary to expectations the stability region of the compound Ni12−xAs8 is very narrow, and occurs at Ni11As8 rather than at Ni3As2. Evidence is presented in support of Hansen's contention that this compound has an incongruent melting point. Alloys in the region corresponding to Ni4.6As2 undergo two transitions below 200 °C, one of which is martensitic and produces a metastable phase, while the other is believed to result in the formation of a new compound, as yet unidentified. The diffraction patterns are discussed in some detail.

High Temperature Implantation in Graphite

1983 ◽  
Vol 27 ◽  
Author(s):  
G. Braunstein ◽  
B.S. Elman ◽  
M.S. Dresselhaus ◽  
G. Dresselhaus ◽  
T. Venkatesan
Keyword(s):  
High Temperature ◽  
Radiation Damage ◽  
High Temperatures ◽  
Room Temperature ◽  
Pyrolytic Graphite ◽  
Rutherford Backscattering ◽  
The Other ◽  
Highly Oriented Pyrolytic Graphite ◽  
Graphite Lattice ◽  
Partial Annealing

ABSTRACTIn previous studies it was found that when highly oriented pyrolytic graphite (HOPG) is implanted at room temperature, the damage caused by the implantation could be completely annealed by heating the sample to temperatures higher than ∼ 2500°C. However at these high temperatures, the implanted species was found to diffuse out of the sample, as evidenced by the disappearance of the impurity peak in the Rutherford backscattering (RBS) spectrum. If, on the other hand, the HOPG crystal was held at a high temperature (≥ 600°C) during the implantation, partial annealing could be observed. The present work further shows that it is possible to anneal the radiation damage and simultaneously to retain the implants in the graphite lattice by means of high temperature implantation (Ti ≥ 450°C) followed by annealing at 2300°C.

4H-SiC PIN Diode as High Temperature Multifunction Sensor

2017 ◽  
Vol 897 ◽  
pp. 630-633 ◽  
Author(s):  
Shuo Ben Hou ◽  
Per Erik Hellström ◽  
Carl Mikael Zetterling ◽  
Mikael Östling
Keyword(s):  
High Temperature ◽  
Bias Voltage ◽  
Temperature Sensitivity ◽  
Room Temperature ◽  
Optical Sensing ◽  
Temperature Sensing ◽  
The Other ◽  
Pin Diode ◽  
Forward Current

An in-house fabricated 4H-SiC PIN diode that has both optical sensing and temperature sensing functions from room temperature (RT) to 550 °C is presented. The two sensing functions can be simply converted from one to the other by switching the bias voltage on the diode. The optical responsivity of the diode at 365 nm is 31.8 mA/W at 550 °C. The temperature sensitivity of the diode is 2.7 mV/°C at the forward current of 1 μA.

Mechanical Properties and Microstructure of Certain Niaico(Hf) Alloys

1990 ◽  
Vol 186 ◽  
Author(s):  
S. M. Russell ◽  
C. C Law ◽  
L. S. Lin ◽  
G. W. Levan
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Low Temperatures ◽  
Creep Resistance ◽  
Room Temperature ◽  
Hexagonal Structure ◽  
High Temperature Strength ◽  
Room Temperature Ductility ◽  
Poor Creep Resistance

AbstractCobalt-modified NiAl alloys are being studied for their potential for room temperature ductility and toughness. An alloy of Ni - 29.3 a/o Al - 36.7 a/o Co has shown improved toughness and ductility with respect to binary NiAl alloys due in part to a stress-induced martensitic transformation. Furthermore, the cobalt additions have altered the slip behavior to {110}<111> type from {110} <001> for binary NiAl alloys. Hafnium was added to improve the alloy's relatively poor creep resistance and high temperature strength. Hf was found to be insoluble in the NiAlCo alloy and formed precipitates with a hexagonal structure. The Hfmodified alloy had improved high temperature strength. In addition, the Hf apparently changed the creep mechanism resulting in poorer creep resistance at low temperatures, but improved creep resistance at higher stresses and temperatures.

Phase Transition and Thermal Expansion of Ba3RB3O9 (R = Sm–Yb, and Y)

2017 ◽  
Vol 36 (8) ◽  
pp. 763-769 ◽  
Author(s):  
Rayko Simura ◽  
Shohei Kawai ◽  
Kazumasa Sugiyama
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Room Temperature ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Melting Temperatures ◽  
Type Phase

AbstractHigh temperature powder X-ray diffraction measurements of Ba3RB3O9 (R=Sm–Yb, and Y) were carried out at temperatures ranging from room temperature to just below the corresponding melting temperatures (1,200–1,300 °C). No phase transition was found for the H-type phase (R$\overline 3 $) with R=Sm–Tb and the L-type phase (P63 cm) with R=Tm–Yb. On the other hand, phase transition from the L phase to the H phase was observed for R=Dy–Er, and Y at around 1,100–1,200 °C. The obtained axial thermal expansion coefficient (ATEC) of the a-axis was larger than that of the c-axis for the H phase, and the ATEC of the c-axis was larger than that of the a-axis for the L phase. The observed anisotropic nature of ATEC is attributed to the distribution of the BO3 anionic group with rigid boron–oxygen bonding in the structures of the H and L phases.

Creep Damage of a Re/Ru-Containing Single Crystal Nickel-Based Superalloy at Elevated Temperature

2019 ◽  
Vol 795 ◽  
pp. 123-129
Author(s):  
Guo Qi Zhao ◽  
Su Gui Tian ◽  
Shun Ke Zhang ◽  
Ning Tian ◽  
Li Rong Liu
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Single Crystal ◽  
Deformation Mechanism ◽  
Creep Resistance ◽  
Creep Damage ◽  
Stress Axis ◽  
Dislocation Configuration ◽  
Nickel Based Superalloy ◽  
Damage And Fracture

By means of creep properties measurement, microstructure observation and contrast analysis of dislocation configuration, the creep behavior of a 4.5%Re/3.0%Ru-containing single crystal nickel-based superalloy at elevated temperature is investigated. Results show that the creep life of the alloy at 1040°C/160MPa is measured to be 725h to exhibit a better creep resistance at high temperature. In the primary stage of creep at high temperature, the γ phase in alloy has transformed into the N-type rafted structure along the direction vertical to the stress axis, the deformation mechanism of alloy during steady state creep is dislocations slipping in γ matrix and climbing over the rafted γ phase. In the latter period of creep, the deformation mechanism of alloy is dislocations slipping in γ matrix and shearing into the rafted γ phase. Wherein the dislocations shearing into the γ phase may cross-slip from {111} to {100} planes for forming the K-W locks to restrain the slipping and cross-slipping on {111} plane, which is thought to be the main reason of the alloy having a better creep resistance. As the creep goes on, the alternate slipping of dislocations results in the twisted of the rafted γ phase to promote the initiation and propagation of the cracks along the interfaces of γ/γ phase up to creep fracture, which is thought to be the damage and fracture mechanism of alloy during creep at high temperature.

High-coercivity Nd-Fe-B Powders Obtained by High-Temperature Milling

2014 ◽  
Vol 59 (1) ◽  
pp. 47-50 ◽  
Author(s):  
W. Kaszuwara ◽  
B. Michalski ◽  
P. Orlowski
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
The Other ◽  
Nanocrystalline Powders ◽  
High Coercivity ◽  
Milling Temperature ◽  
Constituent Elements ◽  
Hard Magnetic Properties

Abstract The possibility of employing high temperature milling (600°C) for the production of highly coercive Nd-Fe-B powders was examined. The materials were the Nd12Fe82B6, alloy which was subjected to mechanical milling and the powders of the constituent elements of this alloy which were processed by mechanical alloying. The processes were conducted in the two variants: the first variant consisted of mechanical milling performed at a high temperature which was maintained during the entire process, and the other variant included preliminary milling carried out at room temperature and then the milling temperature was increased. All the processes gave nanocrystalline powders with hard magnetic properties. The powders produced by mechanical milling had better properties than those produced by mechanical] alloying as they were more homogeneous and contained smaller amounts of the α-Fe phase.

High-Temperature Operation of Electrostatically-Excited Single-Crystalline 4H-SiC Microcantilever Resonators

2015 ◽  
Vol 821-823 ◽  
pp. 914-918
Author(s):  
Kosuke Sato ◽  
Kohei Adachi ◽  
Hajime Okamoto ◽  
Hiroshi Yamaguchi ◽  
Tsunenobu Kimoto ◽  
...  
Keyword(s):  
High Temperature ◽  
Quality Factor ◽  
Room Temperature ◽  
The Other ◽  
Thermoelastic Damping ◽  
High Quality ◽  
Single Crystalline ◽  
Temperature Dependences ◽  
Increasing Temperature ◽  
High Temperature Operation

We fabricated electrostatically-excited single-crystalline 4H-SiC microcantilever resonators with various thicknesses and lengths. Their resonant characteristics were investigated from room temperature (RT) up to 600°C. The resonant frequency of the cantilevers decreased with increasing temperature. From the results, the temperature dependence of Young’s modulus of single-crystalline 4H-SiC was obtained, i.e., 3% decrement with increasing temperature from RT to 600°C. The cantilevers with different thicknesses showed different temperature dependences of the quality factor. A 2-μm-thick cantilever exhibited a high quality factor (Q) (250,000) at RT and the Q decreased to 6,000 at 600°C, which can be explained by thermoelastic damping. On the other hand, a Q of a 0.45-μm-thick cantilever was still high (50,000) even at 600°C.

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

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