Ultrasonic etching delineates microstructural features not discernible in specimens prepared for metallographic analysis by standard chemical etching procedures. Cavitation bubbles in ultrasonically excited water produce preferential damage /etching/ of metallurgical phases or grain boundaries, depending on hardness of metal specimens

Young, S. G.

English

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Ma\ 1971	 Brief 71-10099 
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Ultrasonic Metal Etching for Metallographic Analysis 
Experiments have indicated that selective metal 
etching for metallographic analysis may be achieved 
by an ultrasonic etching method. The ultrasonic 
etch delineates microstructural feature's which may 
not be discernible in specimens prepared for metal-
lographic analysis by standard chemical etching pro-
cedures. 
A magnetostrictive transducer was used to generate 
ultrasonic vibrations which were transmitted to a
layer of distilled water separating the transducer 
head from the metal specimen. Cavitation bubbles in 
the ultrasonically excited water produced preferential 
damage (etching) of the metallurgical phases or 
grain boundaries, depending on the hardness and 
toughness of the phase or structure of the metal 
specimens. The materials studied were the unalloyed 
metals, zinc, nickel 270, iron, and tantalum, and the 
nickel-base alloy Udimet 700. 
An electron microscope replica of the surface of 
the latter, which was subjected to cavitation in water 
at room temperature for two hours, is shown in 
the illustration. 
Notes: 
1. Etched particles may readily be recovered from 
the water (or other liquid) for further analysis. 
2. The following documentation may be obtained 
from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA-TN-D-6014 (N70-38568), Study of 
Cavitation Damage to High-Purity Metals 
and a Nickel-Base Superalloy in Water 
3. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B71-10099
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https://ntrs.nasa.gov/search.jsp?R=19710000098 2020-03-17T02:23:31+00:00Z
Patent status: 
No patent action is contemplated by NASA. 	 S 
Source: S. G. Young
Lewis Research Center 
(LEW-1 1230)
S 
Brief 71-10099	 Category 04


Ultrasonic metal etching for metallographic analysis

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