Hydronalium is a family ofaluminium-magnesium alloys. It is analloy predominantly ofaluminium, with between 1%-12% ofmagnesium as the primary alloying ingredient. It also includes a secondary addition ofmanganese, usually between 0.4%-1%.
The Hydronalium alloys originated in Germany in the 1930s[1][2] and are best known, at least by that name, in Eastern Europe. They were widely used for shipbuilding in Poland.
There are many alloys within this family, one standard reference listing over twenty.[3]
| Alloy | Hardening | Tensile strength | Yield strength | Elongation (%) | Hardness (Brinell) |
|---|---|---|---|---|---|
| Hydronalium 2[3] | Soft | 193 MPa (28,000 psi) | 90 MPa (13,000 psi) | 30 | 47 |
| Hard | 290 MPa (42,000 psi) | 255 MPa (37,000 psi) | 8 | 77 |
The alloy family is noted for its resistance toseawater corrosion.[3] As such it is used in sheet form for boatbuilding and light shipbuilding. As castings it is used for marine fittings. The reliable strength of some grades is sufficient foraerospace use and so they are used for wetted components ofseaplane aircraft, such as floats[2] and propellers, where marine corrosion resistance is also needed.
Some variants of the alloy are ductile enough to be drawn into wire. This, combined with their resistance to corrosion by saltysweat, has led to an application forviolinstrings as an alternative to silver.[4]