Aluminium vs Iron
Aluminium and Iron are genuine alternatives to one another — a choice somebody actually makes — and differ on 6 measured properties, density most clearly.
Aluminium vs Iron
Aluminium
Al
The most abundant metal in the Earth's crust, and until the 1880s more valuable than gold because nobody could extract it cheaply.
| Property | Aluminium | Iron |
|---|---|---|
| Atomic number | 13 | 26 higher |
| Density | 2.7 g/cm³ | 7.874 g/cm³ higher |
| Electrical conductivity | 37.7 MS/m higher | 10 MS/m |
| Melting point | 660.32 °C | 1538 °C higher |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | about 2.75 | about 4 higher |
| Molar mass | 26.982 g/mol | 55.845 g/mol higher |
| Tensile strength Only one of the two has a figure we can stand behind, so there is nothing to compare. | 70–130 MPa | Not known |
| Thermal conductivity Only one of the two has a figure we can stand behind, so there is nothing to compare. | 237 W/(m·K) | Not known |
Choosing between them
Iron is recorded as a substitute for Aluminium — cheaper, stronger.
What it gives up: Rusts, and does so progressively rather than self-limiting the way aluminium's oxide does.
In this application, on the evidence cited above.