ASTM E963-95(2017)
(Practice)Standard Practice for Electrolytic Extraction of Phases from Ni and Ni-Fe Base Superalloys Using a Hydrochloric-Methanol Electrolyte (Withdrawn 2018)
Standard Practice for Electrolytic Extraction of Phases from Ni and Ni-Fe Base Superalloys Using a Hydrochloric-Methanol Electrolyte (Withdrawn 2018)
SIGNIFICANCE AND USE
3.1 This practice can be used to extract carbides, borides, TCP and GCP phases, which can then be qualitatively or quantitatively analyzed by X-ray diffraction or microanalysis.2
3.2 Careful control of parameters is necessary for reproducible quantitative results. Within a given laboratory, such results can be obtained routinely; however, caution must be exercised when comparing quantitative results from different laboratories.3
3.3 Comparable qualitative results can be obtained routinely among different laboratories using this procedure.3
SCOPE
1.1 This practice covers a procedure for the isolation of carbides, borides, TCP (topologically close-packed), and GCP (geometrically close-packed) phases (Note 1) in nickel and nickel-iron base gamma prime strengthened alloys. Contamination of the extracted residue by coarse matrix (gamma) or gamma prime particles, or both, reflects the condition of the alloy rather than the techniques mentioned in this procedure.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. (See 4.3.2.1 and 5.1.1.)
Note 1: Ni3 Ti (eta phase) has been found to be soluble in the electrolyte for some alloys.
FIG. 1 Schematic Diagram of Extraction Cell
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
WITHDRAWN RATIONALE
This practice covers a procedure for the isolation of carbides, borides, TCP (topologically close-packed), and GCP (geometrically close-packed) phases (Note 1) in nickel and nickel-iron base gamma prime strengthened alloys. Contamination of the extracted residue by coarse matrix (gamma) or gamma prime particles, or both, reflects the condition of the alloy rather than the techniques mentioned in this procedure.
Formerly under the jurisdiction of Committee E04 on Metallography, this practice was withdrawn in May 2018. This standard is being withdrawn without replacement due to its limited use by industry.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E963 − 95 (Reapproved 2017)
Standard Practice for
Electrolytic Extraction of Phases from Ni and Ni-Fe Base
Superalloys Using a Hydrochloric-Methanol Electrolyte
This standard is issued under the fixed designation E963; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope of close-packed layers of atoms forming in basket weave nets
aligned with the octahedral planes of the FCC γ matrix. These
1.1 This practice covers a procedure for the isolation of
generally detrimental phases appear as thin plates, often
carbides, borides, TCP (topologically close-packed), and GCP
nucleating on grain-boundary carbides. TCPphases commonly
(geometrically close-packed) phases (Note 1) in nickel and
found in nickel alloys are σ, µ , and Laves.
nickel-iron base gamma prime strengthened alloys. Contami-
nation of the extracted residue by coarse matrix (gamma) or
3. Significance and Use
gamma prime particles, or both, reflects the condition of the
3.1 This practice can be used to extract carbides, borides,
alloy rather than the techniques mentioned in this procedure.
TCP and GCP phases, which can then be qualitatively or
1.2 This standard does not purport to address all of the
quantitatively analyzed by X-ray diffraction or microanalysis.
safety concerns, if any, associated with its use. It is the
3.2 Careful control of parameters is necessary for reproduc-
responsibility of the user of this standard to establish appro-
ible quantitative results.Within a given laboratory, such results
priate safety, health, and environmental practices and deter-
can be obtained routinely; however, caution must be exercised
mine the applicability of regulatory limitations prior to use.
when comparing quantitative results from different laborato-
(See 4.3.2.1 and 5.1.1.)
ries.
NOTE 1—Ni Ti (eta phase) has been found to be soluble in the
electrolyte for some alloys. 3.3 Comparablequalitativeresultscanbeobtainedroutinely
among different laboratories using this procedure.
1.3 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4. Apparatus
ization established in the Decision on Principles for the
4.1 Cell or Container for Electrolyte— A glass vessel of
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical about 400-mL capacity is recommended. For the sample size
and current density recommended later in this procedure,
Barriers to Trade (TBT) Committee.
electrolysis can proceed up to about 4 h, and up to about4gof
2. Terminology
alloy can be dissolved in 250 mL of electrolyte without
2.1 Definitions:
exceeding a metallic ion concentration of 16 g/L. Above this
2.1.1 extraction cell—laboratory apparatus consisting of a concentration, cathode plating has been observed to be more
beaker to contain the electrolyte, a dc power supply, a noble
likely to occur. A mechanism for cooling the electrolyte is
metal sheet or screen cathode and a noble metal wire basket or recommended. For example, an ice water bath or water-
wire to affix to the sample (anode).
jacketed cell may be used to keep the electrolyte between 0°
2.1.2 geometrically close-packed (GCP) phases— and 30°C.
precipitated phases found in nickel-base alloys that have the
4.2 Cathode—Material must be inert during electrolysis.
form A B, where B is a smaller atom than A. In superalloys,
Tantalum and platinum sheet or mesh are known to meet this
these are the common FCC Ni (Al, Ti) or occasionally found
requirement. Use of a single wire is to be avoided, since
HCP Ni Ti.
cathode surface area should be larger than that of sample.
2.1.3 topologically close-packed (TCP) phases— precipi-
Distance between sample and cathode should be as great as
tated phases in nickel-base alloys, characterized as composed
1 2
This practice is under the jurisdiction of ASTM Committee E04 on Metallog- Donachie, M. J. Jr., and Kriege, O. H., “Phase Extraction and Analysis in
raphy and is the direct responsibility of Subcommittee E04.11 on X-Ray and Superalloys—Summary of Investigations byASTM Committee E-4 Task Group I,”
Electron Metallography. Journal of Materials , Vol 7, 1972, pp. 269–278.
Current edition approved June 1, 2017. Published March 2017. Originally Donachie, M. J. Jr., “Phase Extraction and Analysis in Superalloys—Second
approved in 1983. Last previous edition approved in 2010 as E963 – 95 (2010). Summary of Investigations by ASTM Subcommittee E04.91,” Journal of Testing
DOI: 10.1520/E0963-95R17. and Evaluation, Vol 6, No. 3, 1978, pp. 189–195.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E963 − 95 (2017)
FIG. 1 Schematic Diagram of Extraction Cell
possible, within the size of cell chosen. For example, a sample density fluctuation of about 65 % which, for samples under 15
2 2
with a surface area of 15 cm should have no side closer than cm total surface area, is less than or equal to one-half the
1.2 cm to the cathode. If the cell is cylindrical, as for the case current density shift due to sample shrinkage over 4 h.
ofabeakerortheupperpartofaseparatoryfunnel,thecathode Potentiostatic control is not necessary, but may be helpful for
could be curved to fit the inner cell wall to facilitate correct determining optimum current density when setting up proce-
sample-cathode distance. The sample would then be centered dures for a new alloy.
within the cell at the same height as the cathode. The cathode
4.5 Membrane Filter—Must be solvent and electrolyte
need not make a complete ring around the sample nor be more
resistant, with pore size of 0.4 to 0.8 µm. Filters made of
than 5 cm high.
poly(vinyl chloride) (fibrous) or polycarbonate (nonfibrous)
4.3 Anode—The sample must be suspended in the electro- meet these requirements and are available commercially, as are
lyte by a material that is inert during electrolysis. Anode suitable filter holder assemblies. Mass loss for these materials
connection material should be cleaned to prevent any contami- in 10 % HCl-methanol is 10 %. The 2.5-cm diameter size is
nating material from falling into the cell. Good electrical useful for preparing the residue for the X-ray diffractometer,
contact should be maintained between the sample wire and the which is commonly used for phase analysis of the residue.
permanent anode wire from the dc power supply.Two methods Otherwise, filter diameter is not critical. Filters should be
are found to be successful. Either method is subject to handled with blunt tweezers.
disconnection of the sample due to shrinkage, which puts a
4.6 Centrifuge—Centrifuging for residue collection can be
limit on the electrolysis time:
performed as an alternate to microfiltration.
4.3.1 Suspend the sample by platinum or platinum-rhodium
4.7 Balance—If quantitative analysis is desired, a balance
thermocouple wire (20 gauge) wrapped around it to form a
sensitive to 0.0001 g is required.
basket. To avoid a shielding problem, the ratio of sample area
covered by the wire to the exposed sample area should be
5. Reagents
small.
5.1 Electrolyte—Add and mix 1 part of 12 N hydrochloric
4.3.1.1 Mechanically attach or spot weld the platinum or
acid (sp gr 1.19) to 9 parts of absolute methyl alcohol by
platinum-rhodium thermocouple wire to the sample.
volume to make a 10 % HCl-methanol solution. For alloys
4.3.2 If the weld is not immersed, non-inert wire may be
containing W, Nb, Ta, or Hf, add one part by weight tartaric or
substituted; for example, chromel, nichrome, 300 series stain-
citric acid to 100 parts by volume HCl-methanol to make an
less steel, etc. Stop-off lacquer should be used below the
approximately 1 % tartaric or citric acid solution. All reagents
meniscus to maintain constant electrolyte level. This also
should be of at least ACS reagent grade quality.
eliminates formation of insoluble deposits immediately above
5.1.1 Warning—Add hydrochloric acid to absolute methyl
the meniscus and prevents arcing.
alcohol slowly and with constant stirring; otherwise sufficient
4.3.2.1 Warning—Care must be taken to prevent arcing
heat is generated to cause a hazardous condition. Mixing must
between anode and cathode which could ignite the methanol.
be done in an exhaust hood, because the fumes are toxic.
4.4 Power Supply—A variable dc power supply capable of
5.2 Sample and Residue Rinse—Absolute methyl alcohol is
providing 0 to 5 V is needed to obtain currents from 0 to 1.2A
to be used.
depending on total surface area of the sample. For example, a
sample with total surface area of 15 cm , electrolyzed at a
6. Procedure
current density of 0.1 A/cm , requires:
6.1 Sample Size and Geometry—A cube, cylinder, or rect-
2 2
15 cm 30.1 A/cm 5 1.2 A (1)
angular prism is preferred. Ideally, constant density should be
4.4.1 Current and voltage fluctuation should be no more maintained during electrolysis. Flattened samples, especially
than 65%. A 65 % current fluctuation represents a current thin sheet, will experience considerable shrinkage due to edge
E963 − 95 (2017)
effects and current density increase as the electrolysis pro- thewel
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