ASTM E963-95(2000)
(Practice)Standard Practice for Electrolytic Extraction of Phases from Ni and Ni-Fe Base Superalloys Using a Hydrochloric-Methanol Electrolyte
Standard Practice for Electrolytic Extraction of Phases from Ni and Ni-Fe Base Superalloys Using a Hydrochloric-Methanol Electrolyte
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 and health practices and determine the applicability of regulatory limitations prior to use. (See 3.3.2.1 and 4.1.1.)
Note 1--Ni3 Ti (eta phase) has been found to be soluble in the electrolyte for some alloys.
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Designation: E 963 – 95 (Reapproved 2000)
Standard Practice for
Electrolytic Extraction of Phases from Ni and Ni-Fe Base
1
Superalloys Using a Hydrochloric-Methanol Electrolyte
This standard is issued under the fixed designation E 963; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
1.1 This practice covers a procedure for the isolation of 3.1 This practice can be used to extract carbides, borides,
carbides, borides, TCP (topologically close-packed), and GCP TCP and GCP phases, which can then be qualitatively or
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(geometrically close-packed) phases (Note 1) in nickel and quantitatively analyzed by X-ray diffraction or microanalysis.
nickel-iron base gamma prime strengthened alloys. Contami- 3.2 Careful control of parameters is necessary for reproduc-
nation of the extracted residue by coarse matrix (gamma) or ible quantitative results. Within a given laboratory, such results
gamma prime particles, or both, reflects the condition of the can be obtained routinely; however, caution must be exercised
alloy rather than the techniques mentioned in this procedure. when comparing quantitative results from different laborato-
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1.2 This standard does not purport to address all of the ries.
safety concerns, if any, associated with its use. It is the 3.3 Comparable qualitative results can be obtained routinely
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responsibility of the user of this standard to establish appro- among different laboratories using this procedure.
priate safety and health practices and determine the applica-
4. Apparatus
bility of regulatory limitations prior to use. (See 3.3.2.1 and
4.1.1.) 4.1 Cell or Container for Electrolyte— A glass vessel of
about 400-mL capacity is recommended. For the sample size
NOTE 1—Ni Ti (eta phase) has been found to be soluble in the
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and current density recommended later in this procedure,
electrolyte for some alloys.
electrolysis can proceed up to about 4 h, and up to about4gof
2. Terminology alloy can be dissolved in 250 mL of electrolyte without
exceeding a metallic ion concentration of 16 g/L. Above this
2.1 Definitions:
concentration, cathode plating has been observed to be more
2.1.1 extraction cell—laboratory apparatus consisting of a
likely to occur. A mechanism for cooling the electrolyte is
beaker to contain the electrolyte, a dc power supply, a noble
recommended. For example, an ice water bath or water-
metal sheet or screen cathode and a noble metal wire basket or
jacketed cell may be used to keep the electrolyte between 0°
wire to affix to the sample (anode).
and 30°C.
2.1.2 geometrically close-packed (GCP) phases—
4.2 Cathode—Material must be inert during electrolysis.
precipitated phases found in nickel-base alloys that have the
Tantalum and platinum sheet or mesh are known to meet this
form A B, where B is a smaller atom than A. In superalloys,
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requirement. Use of a single wire is to be avoided, since
these are the common FCC Ni (Al, Ti) or occasionally found
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cathode surface area should be larger than that of sample.
HCP Ni Ti.
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Distance between sample and cathode should be as great as
2.1.3 topologically close-packed (TCP) phases— precipi-
possible, within the size of cell chosen. For example, a sample
tated phases in nickel-base alloys, characterized as composed
2
with a surface area of 15 cm should have no side closer than
of close-packed layers of atoms forming in basket weave nets
1.2 cm to the cathode. If the cell is cylindrical, as for the case
aligned with the octahedral planes of the FCC g matrix. These
of a beaker or the upper part of a separatory funnel, the cathode
generally detrimental phases appear as thin plates, often
could be curved to fit the inner cell wall to facilitate correct
nucleating on grain-boundary carbides. TCP phases commonly
found in nickel alloys are s, μ , and Laves.
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Donachie, M. J. Jr., and Kriege, O. H., “Phase Extraction and Analysis in
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This practice is under the jurisdiction of ASTM Committee E04 on Metallog- Superalloys—Summary of Investigations by ASTM Committee E-4 Task Group I,”
raphy and is the direct responsibility of Subcommittee E04.11 on X-Ray and Journal of Materials, Vol 7, 1972, pp. 269–278.
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Electron Metallography. Donachie, M. J. Jr., “Phase Extraction and Analysis in Superalloys—Second
Current edition approved Jan. 15, 1995. Published March 1995. Originally Summary of Investigations by ASTM Subcommittee E04.91,” Journal of Testing
published as E 963 – 83. Last previous edition E963 – 83 (1989). and Evaluation, Vol 6, No. 3, 1978, pp. 189–195.
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