The thermal conductivity of aluminium at cryogenic temperatures varies by many orders of magnitude. Values for different alloys vary by about a factor of ten, while those for pure aluminium of different purities vary by more than three orders of magnitude. It is therefore not possible to give a single set of recommended conductivity values for aluminium.
However, a set of equations have been created which can extrapolate the thermal
conductivity of aluminium from a measurement at a single temperature
to the entire temperature range from the superconducting transition
(about 1 K) to 300 K. Equivalently, an electrical resistitivity or RRR
value may be used.
These equations apply to both pure aluminium
and aluminium alloys.
The figure below shows conductivity values for various aluminium alloys, produced by using these equations to extrapolate the results of measurements in the literature taken over restricted temperature ranges. For clarity, some types with similar values have been grouped together. For various reasons, including sample to sample variations, these values should be taken as an indication only. More information is given here, with a more detailed explanation in reference , from which the figure below was taken.
These links provide tabulated conductivity values for the alloys shown above: 2014 (T651) 2024 (O) 2024 (T4) 2024 (T6) 2024 (T86) 2219 (T81) 3003 (F) 5052 (O) 5083 (O) 5086 (F) 5154 (O) 6061 (T6) 6063 (T5) 6082 (T6) 7039 (T61) 7075 (T6) 7075 (T73) The advanced aluminium thermal conductivity calculator can be used to produce values for other alloys, if you know the electrical or thermal conductivity at 4 K.
For pure aluminium, the best that can be done is to offer a range of likely values for a given nominal purity. These are shown below for annealed aluminium with 4N (99.99%) to 6N (99.9999%) purity. The dashed lines show values for 5N purity copper, with and without oxygen annealing, for comparison. The graph is taken from reference , which gives more detail.
These links provide tabulated conductivity values for the ranges shown above: 4N - lower limit 4N - upper limit 5N - lower limit 5N - upper limit 6N - lower limit 6N - upper limit. Values for arbitrary RRR (or 4 K conductivity values) can be produced using the advanced aluminium thermal conductivity calculator.
This page is currently in an experimental state. Although the results have been checked, if you are using them for anything important, please check them yourselves (perhaps using the references below).
I would appreciate reports of any problems (contact details given here.)
 J. G. Hust and A. B. Lankford, "Thermal conductivity of aluminium,
copper, iron and tungsten from 1 K to the melting point",
National Bureau of Standards, Boulder, Colorado, 1984. NBSIR 84-3007.
 A. Woodcraft, "Predicting the thermal conductivity of aluminium alloys in the cryogenic to room temperature range", Cryogenics 45(6): 421-432, 2005.
 A. Woodcraft "Recommended values for the thermal conductivity of aluminium of different purities in the cryogenic to room temperature range, and a comparison with copper" Cryogenics 45(9):626-636, 2005.