Liquid-metal thermal paste is a gallium-based thermal interface material (TIM) that can react with copper. In a two-year test by Roman Hartung (der8auer), the reaction formed solid CuGa2, according to Tom’s Hardware’s report published October 16, 2026. The reported result points to the cooler’s surface as an important part of the compatibility question.
What the two-year test observed
Tom’s Hardware reported that Hartung’s sample was liquid after one hour. At two months, no liquid was visible and crystals had formed; at two years, the observed condition had not changed further. Between examination sessions, the setup was stored in a vacuum or nitrogen-filled box to avoid oxidation. Those observations describe Hartung’s test, not a lifetime guarantee for every liquid-metal formula or cooler.
What happens when liquid metal meets copper
In the reported test, gallium reacted with copper to form CuGa2, a solid compound containing one copper atom for every two gallium atoms. The copper-gallium layer reportedly grew by about 1 micrometer per day, reaching roughly 50–100 micrometers depending on temperature and available gallium.
Tom’s Hardware gives the thermal conductivity of CuGa2 as about 100 W/mK and copper’s as roughly 400 W/mK. The 100 W/mK figure describes the reaction product, not liquid Conductonaut. In a separate demonstration, Hartung could not wipe the film from the tested copper cold plate with isopropyl alcohol or acetone after less than five minutes of contact.
Copper, nickel plating, and aluminum
| Cooler surface | Reported interaction |
| Bare copper | Gallium reacted with copper to form solid CuGa2. |
| Nickel-plated surface | Gallium formed NiGa5, a solid compound with one nickel atom for every five gallium atoms. The reported reaction layer was thinner than on copper. |
| Aluminum | In a separate demonstration, a 2 mm sheet swelled after about five minutes and became brittle within half an hour after its oxide layer was broken and gallium could interact with the metal. |
Thermal Grizzly describes Conductonaut as an electrically conductive eutectic alloy involving tin, gallium, and indium. The company recommends nickel-plated surfaces for Conductonaut’s best long-term performance and says not to use it with aluminum coolers. Those instructions apply to Conductonaut specifically.
