ALLIAGE DE MAGNESIUM RESISTANT AU FLUAGE

CREEP-RESISTANT MAGNESIUM ALLOY

Abrégé anglais

The present invention relates to a magnesium aluminum alloy with enhanced
creep resistance.
The alloy contains barium and calcium in low proportions, and possesses a
higher creep
resistance in comparison to alloys containing rare earth elements. The alloy
may additionally
include zinc, tin, lithium, manganese, yttrium, neodymium, cerium and/or
praseodymium in
proportions of up to 7 % by weight, respectively.

Revendications

WE CLAIM:
1. Magnesium alloy, containing the following ingredients, based on total
weight of the alloy:
1 to 9 % by weight of aluminum
0.5 to 5 % by weight of barium
0.5 to 5 % by weight of calcium and
the balance being magnesium.
2. The magnesium alloy according to claim 1, characterized in that it
additionally includes
zinc, tin, lithium, manganese, yttrium, neodymium, cerium and/or praseodymium
in proportions
of up to 7 % by weight, respectively.
3. The magnesium alloy according to claim 1 or 2, characterized in that the
proportion of
aluminum is 2 to 7 % by weight, preferably 3 to 6 % by weight.
4. The magnesium alloy according to any one of claims 1 to 3, characterized in
that the
proportion of barium is 1 to 4 % by weight, preferably 1.5 to 3 % by weight.
5. The magnesium alloy according to any one of claims 1 to 4, characterized in
that the
proportion of calcium is 1 to 4 % by weight, preferably 1.5 to 3 % by weight.
6. Use of a magnesium alloy according to any one of claims 1 to 5 in the
production of
components of automotives, vessels and/or aeroplanes.
7. Use of a magnesium alloy according to any one of claims 1 to 5 in the
production of
power trains or components thereof.
4

Description

CA 02675863 2009-08-18
Agent Ref: 71404/00005
1 CREEP-RESISTANT MAGNESIUM ALLOY
2
3 FIELD OF THE INVENTION
4 The present invention relates to a creep-resistant magnesium alloy.
6 BACKGROUND OF THE INVENTION
7 Metal alloys containing magnesium are used extensively in the automotive
industry,
8 electronic industry, aerospace industry and several other technical areas.
Those alloys are
9 especially advantageous, which are high temperature creep-resistant and
therefore usable in a
high temperature environment.
11
12 Several different magnesium alloys have been developed and standardized,
such as the
13 magnesium alloys JIS H 5203 (MC1-MC10) and JIS H 5303 (MDC1A, MDC1B). Alloy
A having
14 the composition Mg-4%AI-2%RE (RE = rare earth elements), which has been
developed by the
company Dow Chemical, is also well known for high temperature use.
16
17 However, such heat-resistant magnesium alloys are quite inapplicable in
casting,
18 wherein the metal object must be cooled rapidly after shaping.
19
DE 44 46 898 Al discloses creep-resistant magnesium alloys, containing: 1.5 to
10 % by
21 weight of aluminum (Al), less than 2 % by weight of rare earth elements
(RE), 0.25 to 5.5 % by
22 weight of calcium (Ca), the balance being magnesium. In addition, the alloy
may contain 0.2 to
23 2.5 % by weight of copper and/or zinc.
24
The rare earth elements contained in such alloys, however, increase the costs
of the
26 alloy.
27
28 DE 22 01 460 Al also discloses creep-resistant magnesium alloys containing
aluminum
29 and optionally an additional element selected from calcium, zirconium,
titanium, silicon,
strontium, yttrium, cerium or barium. Barium and calcium in combination are
not disclosed as
31 additional elements.
32
1
21912040.1

CA 02675863 2009-08-18
Agent Ref: 71404/00005
1 SUMMARY OF THE INVENTION
2 It is therefore the object of the present invention to provide a magnesium
alloy, which is
3 able to overcome the above mentioned disadvantages of the state of the art
and, moreover, has
4 a higher creep resistance.
6 In one aspect, the invention provides a magnesium alloy, containing the
following
7 ingredients, based on total weight of the alloy: 1 to 9 % by weight of
aluminum; 0.5 to 5 % by
8 weight of barium; 0.5 to 5 % by weight of calcium; and with the balance
being magnesium.
9
BRIEF DESCRIPTION OF THE FIGURE
11 Figure 1 illustrates creep deformation as a function of time.
12
13 DETAILED DESCRIPTION OF THE INVENTION
14 The object is solved by a metal alloy containing magnesium or magnesium
alloy,
containing 1 to 9 % by weight of aluminum (AI), 0.5 to 5 % by weight of barium
(Ba), 0.5 to 5 %
16 by weight of calcium (Ca), the balance being magnesium (Mg) and inevitable
production-related
17 impurities, based on the total weight of the alloy. Preferably, the
inevitable production-related
18 impurities amount in total to no more than 2 % by weight, based on the
total weight of the alloy.
19 The proportion of aluminum is preferably 2 to 7 % by weight, more
preferably 3 to 6 % by
weight. The proportion of barium is preferably 1 to 4 % by weight, more
preferably 1.5 to 3 % by
21 weight. The proportion of calcium is preferably 1 to 4 % by weight, more
preferably 1.5 to 3 %
22 by weight.
23
24 The magnesium alloy of the invention may additionally include zinc, tin,
lithium,
manganese, yttrium, neodymium, cerium and/or praseodymium in proportions of up
to 7 % by
26 weight, respectively.
27
28 The magnesium alloy of the invention may be used in a multiplicity of
application areas;
29 preferably it is used in the production of components for automotives,
vessels and/or
aeroplanes, more preferably in the production of power trains and components
thereof.
31
32 The invention is further illustrated with reference to the attached figure.
In figure 1, the
33 creep deformation as a function of time with an applied strain of 80 MPa
and a temperature of
34 200 C of two inventive magnesium alloys (referred to as "ABC alloys", or
aluminum, barium and
21912040.1 2

CA 02675863 2009-08-18
Agent Ref: 71404/00005
1 calcium alloys) containing about 4 % by weight of aluminum, about 2 % by
weight of barium and
2 about 1 % by weight of calcium ("ABC421 ") and about 4 % by weight of
aluminum, about 2 % by
3 weight barium and about 2 % by weight of calcium ("ABC422"), respectively,
is shown in
4 comparison to a conventional alloy AE42, wherein E denotes rare earth
elements, and an alloy
produced by the company Dead Sea Magnesium under the name of MRI230D, which
contains
6 rare earth elements in addition to aluminum and calcium.
7
8 The inventive alloys have a considerably lower creep deformation than the
respective
9 comparison alloys. This leads to the conclusion that, with constant strain,
the temperature may
be increased even further, or that a component may be strained for
considerably prolonged
11 times.
12
13 Although the invention has been described with reference to certain
specific
14 embodiments, various modifications thereof will be apparent to those
skilled in the art without
departing from the purpose and scope of the invention as outlined in the
claims appended
16 hereto. Any examples provided herein are included solely for the purpose of
illustrating the
17 invention and are not intended to limit the invention in any way. Any
drawings provided herein
18 are solely for the purpose of illustrating various aspects of the invention
and are not intended to
19 limit the invention in any way.
21912040.1 3