Separating intermediate phases from zinc-base alloys

Metallography

107

Separating

Intermediate

Phases from

L. NEUMEIER

AND

Zinc-Base Alloys

J. RISBECK

U. S. Department of the Interior, Bureau of Mines, Rolla Metallurgy Research Center, Rolla, Missouri 65401

During copper

research

on wrought

or titanium

or both,

extracting

intermediate-phase

the creep diffraction

and other analysis

zinc-base

a simple

alloys

procedure

particles

containing

small

was devised

from the alloys.

additions

of

for electrolytically

These

phases

influence

properties of the alloys, and they were extracted for x-ray in conjuction with optical microscopy and microprobe

analysis. The particles Examples Fig.

1. The

contained

ranged

from fine to relatively

of the size and distribution extraction

technique

to more than

worked

3 wt o/o-copper

(4

coarse,

of the particles well

often in the same specimen. in rolled alloys are shown

for the

alloys

alloys.

(A) Zn-0.75%

(0 CU; (B) Zn-0.12%

Ti;

Metallography, Copyright

0

in

which

and 1 wt o/o titanium.

(B)

FIG. 1. Cold-rolled Cu-0.36% Ti. 750 x .

studied,

1969 by American

Elsevier

Publishing

and (C) Zn-1.0%

2 (1969)

107-108

Company,

Inc.

108

L. Neumeia and J. R&beck

The specimen is made the anode in a cell with a stainless-steel electrolyte

consisting

cathode and an

of about 10 g of CrO, per 100 ml of water. With about

40 volts dc applied, the zinc solid-solution matrix is selectively dissolved, and the insoluble particles settle to the bottom of the cell. Finer particles may require a day or so to settle completely.

The residue is collected, washed with water or

alcohol, and dried. The matrix of a half-inch

cubic specimen can be completely

dissolved in about an hour. During preparation of a sample, the cathode should be removed several times to wash away decomposed electrolyte. This film formation on the cathode may be minimized by immersing the cell in an ice bath and reducing the voltage, with some sacrifice in dissolution rate. The technique

was devised by J. Fore and M. Adam of the metallography

laboratory at the Rolla (Missouri) Metallurgy Research Center, Bureau of Mines, U.S. Department of the Interior.

Accepted February 20, 1969