Mechanical Spectroscopy in Advanced TiAl-Nb-Mo Alloys at High Temperature

2011 ◽  
Vol 1295 ◽  
Author(s):  
Pablo Simas ◽  
Thomas Schmoelzer ◽  
Maria L. Nó ◽  
Helmut Clemens ◽  
Jose San Juan
Keyword(s):  
High Temperature ◽  
Activation Parameters ◽  
Relaxation Peak ◽  
Thermal Treatments ◽  
Torsion Pendulum ◽  
Hot Workability ◽  
Mechanical Spectroscopy ◽  
Final Microstructure ◽  
Multi Phase ◽  
Internal Friction Spectra

ABSTRACTNew advanced multi-phase γ-TiAl based alloys (TiAl-Nb-Mo), so called TNM alloys, have been developed to promote hot workability and to allow easier processing by conventional forging. However, to control and stabilize the final microstructure, specific processing and further thermal treatments are required. In the present work we used mechanical spectroscopy techniques to obtain a better understanding of the microstructural mechanisms taking place at high temperature applying two different heat treatments. Internal friction spectra and dynamic modulus evolution have been measured in an inverted torsion pendulum up to 1220 K. A stable relaxation peak was observed in both cases at about 1050 K for 1 Hz. Spectra acquired at several frequencies between 0.01 Hz and 3 Hz allow us to measure the activation parameters of this peak. In addition, a high temperature background (HTB) has been observed. This HTB, which has been found to be dependent on thermal treatments, has been analyzed to obtain the apparent activation enthalpy, which seems to be correlated to the creep behavior. Finally, we discuss the relaxation peak and the HTB in terms of the microstructural evolution during thermal treatments.

Relaxation Processes at High Temperature in TiAl-Nb-Mo Intermetallics

2012 ◽  
Vol 1516 ◽  
pp. 41-46 ◽  
Author(s):  
Pablo Simas ◽  
Thomas Schmoelzer ◽  
Svea Mayer ◽  
Maria L. Nó ◽  
Helmut Clemens ◽  
...  
Keyword(s):  
High Temperature ◽  
Relaxation Process ◽  
Activation Parameters ◽  
Relaxation Processes ◽  
Thermal Treatments ◽  
Intermetallic Alloys ◽  
Mechanical Spectroscopy ◽  
Responsible Mechanism ◽  
Defect Mobility

ABSTRACTIn the last decades there was a growing interest in developing new light-weight intermetallic alloys, which are able to substitute the heavy superalloys at a certain temperature range. At present a new Ti-Al-Nb-Mo family, called TNM™ alloys, is being optimized to fulfill the challenging requirements. The aim of the present work was to study the microscopic mechanisms of defect mobility at high temperature in TNM alloys in order to contribute to the understanding of their influence on the mechanical properties and hence to promote the further optimization of these alloys. Mechanical spectroscopy has been used to study the internal friction and the dynamic modulus up to 1460 K of a TNM alloy under different thermal treatments. These measurements allow to follow the microstructural evolution during in-situ thermal treatments. A relaxation process has been observed at about 1050 K and was characterized as a function of temperature and frequency in order to obtain the activation parameters of the responsible mechanism. In particular, the activation enthalpy has been determined to be H= 3 eV. The results are discussed and an atomic mechanism is proposed to explain the observed relaxation process.

Solution and Precipitation Hardening in Carbon-Doped Two-Phase γ-Titanium Aluminides

1996 ◽  
Vol 460 ◽  
Author(s):  
F. Appel ◽  
U. Christoph ◽  
R. Wagner
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Precipitation Hardening ◽  
Titanium Aluminides ◽  
Activation Parameters ◽  
High Temperature Strength ◽  
Thermal Treatments ◽  
Two Phase ◽  
Carbon Doped ◽  
Titanium Aluminide Alloy

ABSTRACTA two-phase titanium aluminide alloy was systematically doped with carbon to improve its high temperature strength. Solid solutions and precipitates of carbon were formed by different thermal treatments. A fine dispersion of perovskite precipitates was found to be very effective for improving the high temperature strength and creep resistance of the material. The strengthening mechanisms were characterized by flow stresses and activation parameters. The investigations were accompanied by electron microscope observation of the defect structure which was generated during deformation. Special attention was paid on the interaction mechanisms of perfect and twinning dislocations with the carbide precipitates.

NIPPON/SUMITOMO SUPER625

Alloy Digest ◽  
2017 ◽  
Vol 66 (12) ◽  
Keyword(s):  
Thermal Stability ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Nickel Alloy ◽  
Hot Workability ◽  
Temperature Performance ◽  
Compositional Elements

Abstract Nippon Sumitomo Super625 is a nickel alloy with an optimization of compositional elements for thermal stability and hot workability. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-740. Producer or source: Sumitomo Metal USA Corporation.

Precipitation Enhancement of "so Called" Defect-Free Czochralski Silicon Material

2005 ◽  
Vol 108-109 ◽  
pp. 11-16
Author(s):  
Timo Müller ◽  
G. Kissinger ◽  
P. Krottenthaler ◽  
C. Seuring ◽  
R. Wahlich ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Treatments ◽  
Low Oxygen ◽  
Zone Formation ◽  
Czochralski Silicon ◽  
Silicon Material ◽  
Free Material ◽  
Precipitation Enhancement

Thermal treatments to enhance precipitation like RTA, ramp anneal and argon anneal were performed on low oxygen 300 mm wafers without vacancy or interstitial agglomerates (“so called” defect-free material). Best results were achieved using high temperature argon anneal leading to a homogenous BMD and denuded zone formation. Furthermore the getter efficiency was positively tested by intentional Ni-contamination. Concepts to overcome the slip danger like improved support geometries and nitrogen codoping were also evaluated and are seen to be beneficial.

High-Temperature Mechanical Relaxation due to Dislocation Motion inside Dislocation Networks

2008 ◽  
Vol 137 ◽  
pp. 21-28 ◽  
Author(s):  
Andre Rivière ◽  
Michel Gerland ◽  
Veronique Pelosin
Keyword(s):  
Internal Friction ◽  
Relaxation Effect ◽  
Dislocation Motion ◽  
Relaxation Peak ◽  
Mechanical Relaxation ◽  
In Situ Tem ◽  
Mechanical Spectroscopy ◽  
Internal Friction Peak ◽  
First Case ◽  
Dislocation Walls

Internal friction peaks observed in single or polycrystals are clearly due to a dislocation relaxation mechanism. Because a sample observed by transmission electron microscopy (TEM) often exhibits in the same time various dislocation microstructures (isolated dislocations, dislocation walls, etc.) it is very difficult to connect the observed relaxation peak with a particular dislocation microstructure. Using isothermal mechanical spectroscopy (IMS), it is easier to compare, for instance, the evolution of a relaxation peak with measurement temperature to the microstructural evolution observed by in-situ TEM at the same temperatures. IMS was used to study a relaxation peak in a 5N aluminium single crystal firstly 1% cold worked and then annealed at various temperatures. TEM experiments performed in the same material at various temperatures equal to the temperatures used for the damping experiments made possible to link this internal friction peak with a relaxation effect occurring inside dislocation walls. In two other experiments in a 4N aluminium polycrystal and in a metal matrix composite with SiC whiskers, it is shown that the observed relaxation peaks are connected to the motion of dislocations inside polygonization boundaries in the first case and in dislocation pile-ups around each whisker in the second one. Theoretical models proposed to explain such relaxation peaks due to a dislocation motion inside a dislocation wall or network are discussed.

CRITICAL ACTIVATION PARAMETERS FOR LaFeAsO-BASED SUPERCONDUCTORS

2011 ◽  
Vol 25 (30) ◽  
pp. 2299-2306
Author(s):  
ZOTIN KWANG-HUA CHU
Keyword(s):  
High Temperature ◽  
Transition Rate ◽  
High Temperature Superconductors ◽  
Activation Parameters ◽  
Iron Pnictides ◽  
Critical Temperatures ◽  
Superconducting Cuprates ◽  
Temperature Environment ◽  
Supersolid Helium ◽  
Very Low Temperature

The occurrence of high-Tc superconductivity in the iron pnictides shares a similar amorphous characteristic with that of high-Tc superconducting cuprates. Here we show that nearly frictionless (electric-field-driven) transport of condensed electrons in amorphous superconductors could happen after using the Eyring's transition-rate approach which has been successfully adopted to study the critical transport of other superconductors as well as supersolid helium in very low temperature environment. The critical temperatures related to the nearly frictionless transport of electrons were found to be directly relevant to the superconducting temperature of high-temperature superconductors (like La [ O 1-x F x] FeAs (x = 0.11-0.12)) after selecting specific activation energies and activation volumes.

Diffusion Phenomena of the Oxygen and Nitrogen in Niobium by Mechanical Spectroscopy

2010 ◽  
Vol 297-301 ◽  
pp. 1346-1353
Author(s):  
Odila Florêncio ◽  
Paulo Sergio Silva ◽  
Carlos Roberto Grandini
Keyword(s):  
Diffusion Coefficients ◽  
Short Range ◽  
Annealed Sample ◽  
Relaxation Processes ◽  
Torsion Pendulum ◽  
Mechanical Spectroscopy ◽  
Interstitial Diffusion ◽  
Relaxation Parameters ◽  
Low Concentrations ◽  
Diffusion Phenomena

The short-range diffusion phenomenon (Snoek Effect) was investigated by mechanical spectroscopy measurements between 300 K and 650 K, in a polycrystalline niobium sample, containing oxygen and nitrogen, using a torsion pendulum. Experimental spectra of anelastic relaxation were obtained under three conditions: as-received sample; annealed sample and subsequently annealed in an oxygen atmosphere for three hours at 1170 K in partial pressure of 5x10-5mbar. The experimental spectra obtained were decomposed in elementary Debye peaks and the anelastic relaxation processes were identified. With anelastic relaxation parameters and the lattice parameters, the interstitial diffusion coefficients of the oxygen and nitrogen in niobium were calculated for each kind of preferential occupation (octahedral and tetrahedral). The results were compared with the literature data, and confirmed that the best adjustment is for the preferential occupation octahedral model for low concentrations of interstitial solutes, but at higher concentration of oxygen were observed deviations of experimental data for the interstitial diffusion coefficients of oxygen in niobium when compared with the literature data, this could be related to the possible occurrence of a double occupation of interstitial sites in the niobium lattice by oxygen interstitials.

Study of High Temperature Properties of AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion

2021 ◽  
Vol 1016 ◽  
pp. 1485-1491
Author(s):  
Marialaura Tocci ◽  
Alessandra Varone ◽  
Roberto Montanari ◽  
Annalisa Pola
Keyword(s):  
High Temperature ◽  
Additive Manufacturing ◽  
Test Temperature ◽  
Vertical Direction ◽  
Material Behavior ◽  
High Temperature Strength ◽  
Powder Bed Fusion ◽  
Mechanical Spectroscopy ◽  
Powder Bed ◽  
Good Thermal Stability

Additive manufacturing of Al alloys can represent an interesting solution for high-performance components in various industrial fields, as for instance the automotive and aerospace industry. Often, for these applications, the alloys are required to withstand exposure to high temperatures. Therefore, the investigation of the evolution of material properties with increasing temperature is of utmost importance in order to assess their suitability for this kind of applications. In the present study, tensile properties at high temperature were investigated for an AlSi10Mg alloy. Samples were manufactured by laser-based powder bed fusion in horizontal and vertical direction in order to examine the influence of building direction on material behavior. The samples were tested in as-built condition and after exposure to high temperature. Tensile tests were performed up to 150 °C and the effect of holding time at the test temperature was evaluated. Furthermore, the alloy was characterized by mechanical spectroscopy in order to evaluate the behavior of dynamic modulus with temperature and, thus, to provide a comprehensive characterization of the material behavior. It was found that the peculiar microstructure of the alloy produced by additive manufacturing is responsible for good high-temperature strength of the material up to 150 °C. The material also exhibits a good thermal stability even after holding at test temperature for 10 h.

Sign in / Sign up

Export Citation Format

Share Document