High speed, automated system accurately measures to approximately one percent in three minutes. System identifies materials having constant thermal or electric conductivity, predicts new material properties, develops alloys in accordance with desired specifications, and develops nondestructive devices for measuring precipitation hardening

Childs, G. E.

Clark, A. F.

Wallace, G. H.

English

NASA Technical Reports Server

May 1971	 Brief 71-10104 
AEC-NASA TECH BRIEF 
Space Nuclear Systems Office 
NASA Tech Briefs announce new technology derived from the US. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech.Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Metal Alloy Resistivity Measurements. at Very Low Temperatures 
A new, high speed, automated system accurately 
measures resistivity characteristics of alloys at low 
temperatures (to 4°K). Measurements are accurate to
urements were obtained in less than half a day 
(exclusive of setup time). Aside from providing a 
rich source of new data, these measurements alsO 
Precision 
Automatic-Current I	 Resistor 
Reversing 
Switch
II	 --	 —	 — 
Floating	 — 
Constant	 Automatic Scanne 
Current	 Digital Voltmeter 
Supply	 Printer	
- 
approximately 1%, and can be taken in three minutes, 
where previous manual systems required an hour or 
more, exclusive of setup time. 
An automatic-scanner digital-voltmeter combination 
(see fig.) reads the voltages across the sample 
potential leads and across the precision resistor po-
tential leads, to give an indication of current. The 
scanner then trips the automatic current reversing 
switch, and repeats the sequence every 10 seconds 
for 19 successive readings. The averaging method thus 
obtained eliminates the effects of spurious ther-
moelectric voltages. A simple dip-probe, designed 
specifically for this system, is used to hold the 
sample in place. 
The system was used to take resistivity measure-
ments on 65 different alloys of aluminum, nickel, 
copper, titanium, and iron, at five different tempera-
tures ranging from 273°K to 4°K. Eighty-one meas-
Cryogen *SampIe 
Storage 
Dewar 
*Hold in Dip-Probe, not shown 
produced a broader base for understanding the be-
havior of alloys. For example, thermal conductivity 
can be predicted from the more easily measured 
electrical resistivity and Lorenz ratio for a given 
class of similar alloys; low temperature electrical re-
sistivity of an alloy within a given class can be 
reliably predicted from a room temperature meas-
urement; the degree of precipitation hardening can be 
directly correlated to electrical resistivity; and, the 
(continued overleal) 
- This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000103 2020-03-17T02:23:24+00:00Z
resistivity of an unknown alloy can be calculated 
from the specific resistivities of known alloys, if 
one impurity is dominant, or if the total impurity 
content is less than approximately 5%. 
Because of its versatility, the system can be used 
to identify known or new materials having a con-
stant thermal or electrical conductivity, to predict 
properties of new materials, to develop alloys in 
accordance with desired specifications, and to develop 
nondestructive devices for measuring precipitation 
hardening. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
AEC-NASA Space Nuclear Systems Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545 
Reference: B71-10104
Patent status: 
No patent action is contemplated by AEC or NASA. 
Source: A. F. Clark, G. H. Wallace, and
G. E. Childs of
National Bureau of Standards 
under contract to
AEC-NASA Space Nuclear Systems Office 
(NUC- 10557)
. 
S 
Brief 71-10104	 Category 01,04


Metal alloy resistivity measurements at very low temperatures

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