Determination of trace elements in nickel-base superalloys using a high-temperature hollow-cathode source

The Analyst ◽  
1985 ◽  
Vol 110 (6) ◽  
pp. 583 ◽  
Author(s):  
David S. Lowe
Keyword(s):  
Trace Elements ◽  
High Temperature ◽  
Hollow Cathode ◽  
Nickel Base Superalloys ◽  
Nickel Base

The Use of a High Temperature Hollow Cathode Lamp for the Determination of Trace Elements in Steels, Nickel-Base Alloys, and Ferroalloys by Emission Spectrometry

1981 ◽  
Vol 35 (3) ◽  
pp. 302-307 ◽  
Author(s):  
Bo Thelin
Keyword(s):  
Trace Elements ◽  
High Temperature ◽  
Hollow Cathode ◽  
Matrix Effects ◽  
Emission Spectrometry ◽  
Registration System ◽  
Hollow Cathode Lamp ◽  
Boiling Points ◽  
Nickel Base

A high temperature hollow cathode lamp from Applied Research Laboratories, Luton, was used for multielement determination of trace elements in steels, nickel-base alloys and ferroalloys. A 10-mg sample (chips) was placed inside a hollow graphite electrode in the lamp, which was filled with helium. It was possible to raise the power through the lamp linearly and automatically, so that the combined thermal and sputtering effect in the lamp atomized the different elements one after another according to their boiling points. This selective volatilization improved the precision and the limits of detection for the elements determined. Analysis results for Pb, Bi, Zn, Ag, Sb, and Ca in the concentration range 0.05 to 100 μg g−1 are discussed. Because of the effective atomization in the lamp, no matrix effects were observed for these elements. One of the main purposes of this investigation was to study the time dependence of the intensity for the different elements during the volatilization phase. This procedure gave very clean spectra. In this investigation a new computerized image dissector echelle spectrometer, was used as the registration system.

Atomic Absorption Determination of Lead, Bismuth, Selenium, Tellurium, Thallium and Tin in Complex Alloys Using Direct Atomization from Metal Chips in the Graphite Furnace

1977 ◽  
Vol 31 (1) ◽  
pp. 9-11 ◽  
Author(s):  
J. Y. Marks ◽  
G. G. Welcher ◽  
R. J. Spellman
Keyword(s):  
Trace Elements ◽  
Atomic Absorption ◽  
Base Alloy ◽  
Cast Alloy ◽  
Graphite Furnace ◽  
Direct Determination ◽  
Nickel Base Alloy ◽  
Metal Chips ◽  
Nickel Base

Atomic absorption spectrometry utilizing electrothermal atomization devices has proven to be the best technique available for the analysis of complex alloys for trace elements of metallurgical interest. The determination of lead, bismuth, selenium, tellurium, thallium, and tin was successfully demonstrated by direct atomization from complex, nickel-base alloy chips with commercial atomic absorption furnace equipment. The determination was carried out by first milling metal chips from the bulk sample. The sample was transferred directly to the furnace and atomized immediately with no preatomization heating cycle. A series of cast alloy standards containing the trace elements were prepared by additions to a nickel-base alloy, then subsequently analyzed by established analytical methods. Of the three commercial atomizers studied, the Perkin-Elmer model HGA 2100 proved to be the most suitable for direct determination of the trace elements of interest. The coefficient of variation of absorbance measurements varied from 7% for bismuth which is easily atomized to 25% for tin which is more difficult to atomize.

Advancements in Fast Epitaxial High-Temperature Brazing of Single-Crystalline Nickel-Base Superalloys

2009 ◽  
Author(s):  
Britta Laux ◽  
Sebastian Piegert ◽  
Joachim Ro¨sler
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Base Material ◽  
Secondary Phases ◽  
Single Crystalline ◽  
Thermodynamic Simulations ◽  
Nickel Base Superalloys ◽  
Stray Grains ◽  
Nickel Base ◽  
Nickel Manganese

High temperature diffusion brazing is a very important technology for filling cracks in components from single-crystalline nickel-base superalloys as used in aircraft engines and stationary gas turbines: alloys, which are similar to the base material, are enhanced by a fast diffusing melting-point depressant (MPD) like boron or silicon, which causes solidification by diffusing into the base material. Generally, epitaxial solidification of single-crystalline materials can be achieved by use of conventional braze alloys, however, very long hold times are necessary to provide a complete diffusion of the MPD out of the braze gap. If the temperature is lowered before diffusion is completed, brittle secondary phases precipitate, which serve as nucleation sites for stray grains and, therefore, lead to deteriorating mechanical properties. It was demonstrated in earlier works that nickel-manganese-based braze alloys are appropriate systems for the braze repair of particularly wide gaps in the range of more than 200 μm, which allow a significant shortening of the required hold times. This is caused by the complete solubility of manganese in nickel: epitaxial solidification can be controlled by cooling in addition to diffusion. In this work, it will be shown that the nickel-manganese-based systems can be enhanced by chromium and aluminium, which is with regard to high-temperature applications a very important aspect. Furthermore, it will be demonstrated that silicon, which could be identified as appropriate secondary MPD in recent works, can be replaced by titanium, as this element has additionally a γ′ stabilizing effect. Several braze alloys containing nickel, manganese, chromium, aluminium and titanium will be presented. Previously, the influence of the above mentioned elements on the nickel-manganese-based systems will be visualized by thermodynamic simulations. Afterwards, different compositions in combination with a heat treatment, which is typical for nickel-base superalloys, will be discussed: a microstructure, which is very similar to that within the base material can be presented.

Determination of the Coherency Strain of γ and γ′ Phases in Nickel-Base Superalloys at High Temperatures

1992 ◽  
Vol 36 ◽  
pp. 515-526
Author(s):  
Katsumi Ohno ◽  
Tadaharu Yokokawa ◽  
Toshihiro Yamagata ◽  
Hiroshi Harada ◽  
Michio Yamazaki ◽  
...  
Keyword(s):  
Lattice Misfit ◽  
Profile Fitting ◽  
Overlapping Peaks ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
L12 Structure ◽  
Fcc Structure ◽  
Type Nickel ◽  
Voigt Function

AbstractA method for using syncrotoron-radiation parallel-beam X-ray diffractometry for precise lattice parameters and strains of γ-γ′ type Nickel base superalloys at elevated temperature is described. The superalloys have γ′ precipitates which are an ordered L12 structure based on Ni3Al, in y-matrices having a disordered FCC structure. Lattice misfit between γ and γ′ phases was very small and peaks reflected from γ and γ′ phases made unresolved clusters of peaks.Profile fitting with a pseudo-Voigt function is used to resolve overlapping peaks. Instrumental broadening of the peak profile was removed using a deconvolution method. The standard errors of the calculated peak angle were less than 0.002°. The elastic strain of the γ′ precipitates in the alloys were smaller than those of γ-matrices.

Sign in / Sign up

Export Citation Format

Share Document