# Patent

## Title
Aluminum alloy

## Abstract

The invention relates to an aluminum alloy having good electrical conductivity and good thermal conductivity for producing die-cast components, containing: 8.0 to 9.0 wt % silicon, 0.5 to 0.7 wt % iron, max. 0.010 wt % copper, max. 0.010 wt % magnesium, max. 0.010 wt % manganese, max. 0.001 wt % chromium, max. 0.020 wt % titanium, max. 0.020 wt % vanadium, max. 0.05 wt % zinc, 0.010 to 0.030 wt % strontium, and aluminum as the rest, with further elements and manufacturing-caused impurities individually max. 0.05 wt %, in total max. 0.2 wt %. The alloy is suited in particular for producing components having good electrical conductivity and good thermal conductivity in the die casting process.

## Background
The invention relates to an aluminum alloy having good electrical conductivity and good thermal conductivity for producing die-cast components.
The standardized alloy LM 6 in accordance with BS 1490 (AC 47000, AlSi12(Cu)) is routinely used for components having good electrical conductivity and good thermal conductivity produced by die casting, for example as cooling elements used as covering for the electronics in automobiles.
It is an object of the invention to provide an aluminum alloy which is suitable for die casting and has an improved electrical conductivity and thermal conductivity compared to the alloys known from the prior art.


The object of the invention is achieved by the alloy containing
from 8.0 to 9.0% by weight of silicon
from 0.5 to 0.7% by weight of iron
not more than 0.010% by weight of copper
not more than 0.010% by weight of magnesium
not more than 0.010% by weight of manganese
not more than 0.001% by weight of chromium
not more than 0.020% by weight of titanium
not more than 0.020% by weight of vanadium
not more than 0.05% by weight of zinc
from 0.010 to 0.030% by weight of strontium
and aluminum as balance with further elements and production-related impurities of not more than 0.05% by weight each, in total not more than 0.2% by weight.
In a preferred variant of the alloy of the invention, the sum of the elements manganese, titanium, vanadium and chromium is ≦0.02% by weight.
A preferred field of application for the aluminum alloy of the invention is the production of components having good electrical conductivity and good thermal conductivity, for example cooling elements for electronic components, by die casting.
Further advantages, features and details of the invention are indicated in the following description of a preferred example and with the aid of two comparative examples.
The alloy A according to the invention and two comparative alloys B and C having the compositions indicated in Table 1 were cast by die casting starting from a melt temperature of 660° C. at a mold temperature of 150° C. to produce cooling elements for electronic components having a weight of 2.2 kg. After removal from the die casting mold, the specimens were cooled in static air.
The electrical conductivity was measured at two different measurement points M1 and M2 on the die-cast components. The results shown in Table 2 demonstrate the superiority of the alloy A according to the invention over the comparative alloys B and the registered standard alloy C (LM6 in accordance with BS 1490, AC 47000, AlSi12(Cu)). The comparative alloy B differs from the alloy A according to the invention essentially in that the silicon content is higher.
Table 3 shows the results of thermal conductivity measurements on the die-cast components made of the alloy A according to the invention and the comparative alloy C. Compared to the comparative alloy C, the alloy
A according to the invention displays a thermal conductivity which is from 30 to 40% higher.







TABLE 1







Chemical composition of the alloys in % by


weight
















Al-











loy
Si
Fe
Cu
Mg
Mn
Cr
Ti
V
Sr



















A
8.66
0.60
0.006
0.001
0.005
0.001
0.008
0.006
0.012


B
9.40
0.63
0.008
0.001
0.006
0.001
0.008
0.006
0.008


C
10.0-13.0
0.6
0.1
0.10
0.5
—
0.2
—
—
















TABLE 2







Electrical conductivity










Measurement point
Measurement point


Alloy
M1 [m/Ωmm2]
M2 [m/Ωmm2]





A
26.06
24.48


B
24.35
23.09


C
22.08
21.21
















TABLE 3







Thermal conductivity














Specimen
Thermal



Number of
Temperature
thickness
conductivity


Alloy
measurements
[° C.]
[mm]
[W/mK]





A
5
23
5.76
169.4


C
5
23
3.96
119.1

## Claims

1. An aluminum alloy having electrical conductivity and thermal conductivity that are greater than the electrical conductivity and thermal conductivity of LM6 in accordance with BS 1490, for producing die-cast components, characterized in that the alloy contains
from 8.0 to 9.0% by weight of silicon
from 0.5 to 0.7% by weight of iron
not more than 0.010% by weight of copper
not more than 0.010% by weight of magnesium
not more than 0.010% by weight of manganese
not more than 0.001% by weight of chromium
not more than 0.020% by weight of titanium
not more than 0.020% by weight of vanadium
from 0.010 to 0.030% by weight of strontium and aluminum as balance with further elements and production-related impurities of not more than 0.05% by weight each, in total not more than 0.2% by weight.

2. The aluminum alloy as claimed in claim 1, characterized in that the sum of the elements manganese, titanium, vanadium and chromium is ≦0.02 by weight.

3. A die-cast component composed of an aluminum alloy as claimed in any of claims 1 to 2.

4. The component of claim 3, wherein the component is a cooling element for electronic components.