scholarly journals Lattice Misfit of High Refractory Ruthenium Containing Nickel-Base Superalloys

2011 ◽  
Vol 278 ◽  
pp. 60-65 ◽  
Author(s):  
Steffen Neumeier ◽  
J. Ang ◽  
R.A. Hobbs ◽  
Catherine M.F. Rae ◽  
Howard J. Stone
Keyword(s):  
Lattice Misfit ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Coherency Stress ◽  
Matrix Lattice ◽  
Chemical Segregation ◽  
Nickel Base Superalloys ◽  
Nickel Base

The influence of Ru, Co, Mo and W on the lattice misfit of eight highly alloyed Re containing single crystal nickel-base superalloys was investigated. High resolution X-ray diffraction (XRD) was used to relate the elemental partitioning behavior and the Vegard coefficients of the elements under investigation to the measured lattice parameter of the  and  phase. The residual chemical segregation and especially the coherency stress-induced tetragonal distortion of the  matrix lattice in the high Mo containing alloys results in the observation of two different lattice parameters for the  matrix phase. This leads to three overlapping, but clearly distinguishable {002} X-ray reflections.

Detection of Compositional Fluctuations in High Temperature Exposed Waspaloy

2001 ◽  
Vol 699 ◽  
Author(s):  
Xiaodong Zou ◽  
Tariq Makram ◽  
Rosario A. Gerhardt
Keyword(s):  
Exposure Time ◽  
Structural Integrity ◽  
Thermal Exposure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gamma Prime ◽  
Distribution Shape ◽  
The Matrix ◽  
Quantitative Stereology ◽  
Nickel Base

AbstractWaspaloy is a nickel base super-alloy used in aircraft engines. When this alloy is placed in service, it is subjected to long term exposure at high temperatures, which can cause the reinforcing gamma prime precipitate population to fluctuate and thus affect its structural integrity. The population fluctuates as a result of coarsening, dissolution or re-precipitation. Samples exposed to 1200° F for times ranging from 0 to 12626 hours were characterized using impedance spectroscopy, microhardness measurements, x-ray diffraction and quantitative stereology. Two important parameters were derived from the impedance measurements: (1) the imaginary admittance peak magnitude (Ymax) and (2) the associated relaxation frequency (fmax). As the distribution, shape and size of the precipitates change with exposure time, these parameters were also found to vary. In addition to the changes in precipitate geometry, lattice constant changes detected by analyzing x-ray diffraction data suggest that there are compositional shifts in the matrix as well as the gamma prime precipitates. Furthermore, the preferred orientation of the precipitates can also be seen to change with exposure time. These changes in composition, size and shape as a function of thermal exposure time are accompanied by changes in the volume fractions of primary and secondary gamma prime particles present. Using effective medium models, it is possible to predict that the measured properties are related to the gamma prime population. The grain boundary carbides do not appear to play any role at the conditions presented.

A New Tetragonal Boride Phase in FeAl+B Type Alloys

1996 ◽  
Vol 460 ◽  
Author(s):  
Xavier Pierron ◽  
Ian Baker
Keyword(s):  
Energy Loss ◽  
Lattice Parameter ◽  
Tetragonal Symmetry ◽  
Second Phase ◽  
Boride Phase ◽  
X Ray ◽  
Boron Doped ◽  
The Matrix ◽  
Matrix Lattice ◽  
Electron Energy Loss

ABSTRACTThe structure and composition of a previously unreported second phase were investigated in both Fe-43A1–0.12B and Fe-48Al-0.12B alloys. Energy dispersive x-ray and electron energy loss spectroscopy showed that the precipitates contained boron and were enriched in iron. This new boride phase had a tetragonal symmetry, with at = 4aB2 and ct = aB2, where aB2 is the matrix lattice parameter. The effect of iron content and heat treatments on the microstructure of those two boron-doped FeAl alloys are discussed.

Characterisation of the Structure of Single-Crystal Nickel-Base Superalloys

2010 ◽  
Vol 638-642 ◽  
pp. 2227-2232 ◽  
Author(s):  
Alexander Epishin ◽  
Thomas Link ◽  
Udo Brückner
Keyword(s):  
Single Crystal ◽  
Dendritic Structure ◽  
Experimental Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Kinetics Of ◽  
Morphology Changes ◽  
Sem Investigation

New experimental methods developed by the authors for characterisation of the structure of single-crystal nickel-base superalloys are presented: X-ray diffraction at defined areas of the dendritic structure, none destructive SEM investigation of ’-morphology changes for different creep stresses and times with one specimen, and high resolution SEM investigations of dislocations in the ’-interfaces. Application of these techniques allowed to obtain new results, e.g. about the mosaicity of dendritic subgrains, distribution of the ’-misfit within a single dendrite and kinetics of rafting during creep in the superalloy CMSX-4 in wide temperature and stress ranges.

Oxidation Behavior of Rh-xTi Refractory Alloys

2005 ◽  
Vol 475-479 ◽  
pp. 721-724
Author(s):  
Rabindra Mahapatra ◽  
A.W. Davis
Keyword(s):  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Complex Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Refractory Alloys ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Xrd Techniques ◽  
Lower Oxidation

In this paper we report the oxidation behavior of Rh-xTi (x = 15 & 20 atomic percent) alloys isothermally exposed in air between 1000 and 1300 oC up to a period of 312 hours. The weight gain of arc-melted Rh-15Ti and Rh-20Ti alloys as a function of time was monitored. Results indicate that the oxidation resistance of Rh-15Ti and Rh-20Ti alloys at 1000 and 11000 C is similar to that of advanced nickel-base superalloys. However, these alloys show excellent oxidation resistance beyond the operational limit for nickel-base superalloys. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD) techniques were used to study the microstructure and morphology of the oxides. These alloys oxidize by forming TiO2 and Rh2O3 complex oxides. The Rh-20Ti alloys displayed lower oxidation resistance than Rh-15Ti alloys.

Effect of Trace Element Er on Al-Mg and Al-Mg-Mn Alloys

2007 ◽  
Vol 546-549 ◽  
pp. 899-904 ◽  
Author(s):  
Ze Bing Xing ◽  
Zuo Ren Nie ◽  
Jing Xia Zou ◽  
Xiao Lan Ji ◽  
Xu Dong Wang
Keyword(s):  
Trace Element ◽  
Lattice Parameter ◽  
Heating Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix ◽  
Heterogeneous Nucleus ◽  
Coherent Relationship ◽  
Scanning Electron

The behaviors of trace element Er on binary Al-Mg and ternary Al-Mg-Mn alloys have been investigated through optical microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy and transmission electron microscope. It was found that Er additions more than 0.4% (wt%) produced a remarkable refinement in grain size of Al-Mg and Al-Mg-Mn alloys castings. Er can enhance the tensile strength of the two group experimental alloys significantly but not greatly decrease the elongation due to the formation of many fine like spherical and dispersive primary and precipitation Al3Er particles during casting and heating process. Al3Er particles have L12 crystal structure (space group Pm3m) with a lattice parameter of 0.42119nm, and have a coherent relationship with the matrix phase α-Al (mismatch only 4.1%), which can be acted as the heterogeneous nucleus during solidification to increase the rate of nucleation, and the other hands it can strongly pin up dislocations and subgrain boundaries and retard the recrystallization of alloys.

scholarly journals LATTICE MISFIT MEASUREMENT IN INCONEL 625 BY X-RAY DIFFRACTION TECHNIQUE

2008 ◽  
Vol 22 (23) ◽  
pp. 3977-3985 ◽  
Author(s):  
A. SARKAR ◽  
P. MUKHERJEE ◽  
P. BARAT ◽  
T. JAYAKUMAR ◽  
S. MAHADEVAN ◽  
...  
Keyword(s):  
Profile Analysis ◽  
Parent Phase ◽  
Lattice Misfit ◽  
Inconel 625 ◽  
Line Profile Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructural Parameters ◽  
Diffraction Line Profile ◽  
The Matrix

Determination of lattice misfit and microstructural parameters of the coherent precipitates in Ni based alloy Inconel-625 is a challenging problem as the diffraction peaks of the precipitate and the matrix are completely overlapping. X-ray Diffraction Line Profile Analysis (XRDLPA) has been used to characterize the bulk samples of Inconel 625 at different heat-treated conditions to determine the lattice parameters of the parent phase and also the coherent precipitates by the separation of the overlapping peaks. The lattice misfits of the coherent precipitates with the matrix and their microstructural parameters like size and strain have also been determined.

Hydride structures in Ti-aluminides subjected to high temperature and hydrogen pressure charging conditions

1991 ◽  
Vol 6 (6) ◽  
pp. 1230-1237 ◽  
Author(s):  
D. Legzdina ◽  
I.M. Robertson ◽  
H.K. Birnbaum
Keyword(s):  
Single Phase ◽  
Vacuum Annealing ◽  
Lattice Parameter ◽  
Matrix Composition ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Fcc Structure

The distribution and chemistry of hydrides produced in single and dual phase alloys with a composition near TiAl have been investigated by using a combination of TEM and x-ray diffraction techniques. The alloys were exposed at 650 °C to 13.8 MPa of gaseous H2 for 100 h. In the single-phase gamma alloy, large hydrides preferentially nucleated on the grain boundaries and matrix dislocations and a population of small hydrides was distributed throughout the matrix. X-ray and electron diffraction patterns from these hydrides indicated that they have an fcc structure with a lattice parameter of 0.45 nm. EDAX analysis of the hydrides showed that they were enriched in Ti. The hydrides were mostly removed by vacuum annealing at 800 °C for 24 h. On dissolution of the hydrides, the chemistry of hydride-free regions of the grain boundary returned to the matrix composition, suggesting that Ti segregation accompanied the hydride formation rather than Ti enrichment causing the formation of the hydride. The hydrogen content in the two-phase (γ-α2) alloy was approximately three times that of the single phase alloy, which was presumably a consequence of the presence of the α2-Ti3Al phase in the two-phase alloy. The hydrides in the two-phase material were shown by x-ray diffraction to have an fcc structure and were removed on annealing in vacuum at 800 °C for 24 h.

Determination of Lattice Parameter and Strain of ϒ' Phases in Nickel-Base Superalloys by Synchrotron Radiation Parallel Beam Diffractometry

1990 ◽  
Vol 34 ◽  
pp. 493-499
Author(s):  
Katsumi Ohno ◽  
Kazumasa Ohsumi ◽  
Hiroshi Harada ◽  
Toshihiro Yamagata ◽  
Michio Tamazaki
Keyword(s):  
Synchrotron Radiation ◽  
Preparation Method ◽  
Turbine Blades ◽  
Lattice Misfit ◽  
Lattice Parameter ◽  
Parallel Beam ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Fcc Structure

AbstractThe lattice parameters and strain of ϒ'-phase particles in Nickel-base superalloys, which are duplex type alloys designed for turbine blades and widely called “Ni-base single crystal superalloys”; they are accurately determined by Synchrotron Radiation parallel-beam diffractometry. The superalloys have ϒ' precipitates, an ordered FCC structure based on Ni3Al, in a γ-matrix having disordered FCC structure.In addition, the preparation method of stress-free ϒ'-phase particles, with no composition change in the preparation process, was newly developed to measure the coherency strain of ϒ'-particles due to lattice misfit. The prepared ϒ'-phase particles are similar in composition and form to ϒ'-phase particles in the γ-matrices. The method for determining of the lattice misfit between the γ and γ’ particles was previously reported.

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