Dispersion strengthened alloys having the required properties are produced by a process in which the refractory particles are less than 100 to 500 A thick. These are fine enough to ensure the strength characteristics without appreciable degradation of other characteristics. The alloy consists of a matrix metal and a dispersoid metal

Grant, N. J.

Schilling, W. F.

English

NASA Technical Reports Server

October 1969	 Brief 69-10536 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information-,Springfield, Virginia 2215L, 
Improved Method of Producing Oxide-Dispersion-Strengthened Alloys 
S
The problem: 
To develop an improved method for producing 
wrought alloys consisting of one or more ductile matrix 
metals (e.g., copper) and a uniformly dispersed phase 
of a refractory metal oxide, or oxides (e.g., Al203). 
Since the introduction of the SAP (dispersion-strength-
ened, sintered aluminum powder) method in 1948, 
considerable effort has been expended to produce 
other dispersion-strengthened alloys incorporating a 
ductile metal as a matrix. The dispersed refractory 
oxide generally tends to improve the mechanical pro-
perties of the matrix metal with respect to resistance 
to creep, yield strength, and high-temperature stabil-
ity. In previous methods of preparing alloys of this 
type, however, it was difficult to obtain uniform 
dispersions of sufficiently small-sized particles of the 
refractory oxide in the matrix metal. As a consequence, 
some of the favorable properties (e.g., electrical con-
ductivity and ductility) of the matrix metal would be 
degraded when the alloys were prepared by these 
methods. 
The solution: 
Dispersion-strengthened alloys having the required 
properties are produced by a process in which the 
refractory particles (dispersoid) are reduced in size 
below that of the particles previously obtainable 
economically on a commercial scale. The refractory 
particles which appear in the wrought alloys are in 
the form of flakes less than 100 to 500 angstroms 
thick. These are fine enough to ensure the desired 
strength characteristics without appreciable degrada-
tion of the other characteristics of the alloys. The 
components used to make the alloys consist of a 
matrix metal (such as one of the following: copper, 
nickel, cobalt, iron, molybdenum, tungsten, titanium,
zirconium, niobium, tantalum, or any of their alloys) 
and a dispersoid metal, which has a greater affinity 
for oxygen than the particular matrix metal chosen for 
the alloy. Examples of appropriate dispersoid metals 
are aluminum, beryllium, thorium, titanium, zirconium, 
hafnium, yttrium, and chromium. It is important to 
note that a given metal can function either as a matrix 
metal or a dispersoid metal, depending on the other 
metal used inthe combination. Furthermore, the di-
spersoid metal must be soluble to the extent of at 
least 0.5 atom percent in the matrix metal at loom 
temperature. 
How it's done: 
An example of an alloy produced by the improved 
method is one containing copper as the matrix metal 
and aluminum oxide (Al203 ) as the dispersoid. The 
powder used to make the wrought alloy consists of 
copper and aluminum in solution. This alloy powder 
contains 2.5 to 16.0 atom percent of aluminum (which 
is to be converted in part to the refractory Al203 
dispersoid) and a balance of copper, which serves as 
the matrix metal. This powder is suspended in ethanol, 
and the suspension is subjected to comminution at 
room temperature to convert the powdered material 
to flakes having a thickness preferably no greater than 
0.5 micron and length and width dimensions of 1 to 10 
microns. In the comminution process, the powder 
particles are oxidized to provide flakes consisting of 
aluminum oxide film patches surrounded by copper 
oxide regions in a copper matrix. The flakes, after 
separation from the ethanol and drying, are placed 
in a container which can either be evacuated or filled 
with an inert gas. The temperature of the container is 
raised to about 600° to 850°C, and the flakes are kept 
in this environment to allow the copper oxides to dis-
(continued overleaf) 
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solve and react with the dissolved aluminum in the 
flakes. In this step of the process, the oxygen released 
from the copper oxides is diffused in depth to effect 
internal oxidation of the aluminum. This step can be 
completed in less than 1 hour, depending on the tem-
perature control, to ensure that the matrix copper is 
entirely free of oxygen. The resultant product, con-
taining a fine dispersion of the hard refractory alumi-
num oxide in a ductile copper matrix, is compacted 
and heated to a working temperature in the inert 
environment. The compact may then be extruded or 
otherwise hot-worked to a wrought alloy form. 
Notes: 
1. In one modification of the method, the flakes (from 
the comminution step) are, placed in a reducing 
atmosphere, e.g., hydrogen, to free the matrix 
copper oxide of oxygen, thus eliminating the in-
ternal oxidation step (release of oxygen from the 
copper oxide to convert a chemically equivalent 
amount of aluminum to aluminum oxide).
2. A further advantage of the alloys produced by this 
• method is that a significant amount of the reducing 
metal (aluminum cited in the example) is left in 
solution, thereby increasing the corrosion resistance 
of the alloys. 
3. Inquiries may be directed to: 
Technology Utilization Officer 
NASA Headquarters 
Washington, D.C. 20546 
Reference: B69-10536 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
42 U.S.C. 2457 (f), to the Massachusetts Institute 
of Technology, Cambridge, Mass. 02139. 
Source: N. J. Grant and W. F. Schilling of

Massachusetts Institute of Technology

under contract to

NASA Headquarters
(HQN- 10461)
. 
. 
Brief 69-10536	 Category 03


Improved method of producing oxide-dispersion-strengthened alloys

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