MG · magnesium
Magnesium Alloy Elektron 21 (Mg-Nd-Gd-Zn-Zr)
A rare-earth magnesium alloy for high-temperature service: around 200 °C where the conventional AZ and AM grades have long since crept. Harder than the common grades and slower to machine.
Quoting this material
- Typical lead time
- 25–40 working days
- Condition
- Sand cast or wrought, T6 (solution treated and aged)
- Achievable finish
- Ra 3.2 µm (as cast) typical · Ra 0.8 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
A rare-earth magnesium alloy for high-temperature service: around 200 °C where the conventional AZ and AM grades have long since crept. Harder than the common grades and slower to machine.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength (T6) | 280–300 | MPa |
| Yield strength (T6) | 190–200 | MPa |
| Elongation (T6) | 2–4 | % |
| Service temperature | To 200 | °C |
| Hardness | 75–85 | HB |
| Modulus of elasticity | 45 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Sand cast or wrought, T6 (solution treated and aged)
Heat treatment
Age hardened (T6) to develop the strength and the creep resistance. The rare-earth additions form stable precipitates that resist coarsening at temperature - which is exactly what the conventional magnesium grades cannot do.
Achievable surface finish
Ra 3.2 µm (as cast)
Ra 0.8 µm
Corrosion resistance is better than the AZ grades but a coating system is still standard practice.
Tooling and cutting parameters
Cutting speed
- 200–500 m/min (sharp uncoated carbide)
Feed
- 0.08–0.25 mm/rev turning · 0.06–0.20 mm/tooth milling
Tooling
- Sharp uncoated carbide with generous clearance
Coolant
- Mineral-oil mist or dry
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Aerospace gearbox housings
- Engine and transmission castings
- High-temperature aerospace components
- Defence and missile hardware
- Racing driveline components
DFM notes for this grade
- It is chosen where weight and temperature meet: above about 150 °C the conventional magnesium grades creep, and Elektron 21 holds its shape
- It is typically a sand casting followed by a T6 treatment: the casting route allows the complex housings this material is used for
- The rare-earth content makes it considerably more expensive than AZ91 - specify it for the temperature, not as a general upgrade
Questions buyers ask
- Why does Elektron 21 exist when other magnesium alloys are cheaper?
- Temperature. The common magnesium alloys start creeping at 100–150 °C, so a gearbox housing or an engine casting loses its bolt preload and its geometry. The rare-earth additions hold the structure to around 200 °C, which is what makes a magnesium part viable there at all.
- Is it a casting or a wrought material?
- Primarily cast - sand cast and then T6 treated. That suits the complex housings it is used for, and it means the machining is a finishing operation on a near-net shape rather than a part cut from bar.
Grades we would quote instead
ZK60A
7/10A zirconium-containing magnesium alloy with the highest strength of the conventional grades.
AZ80A
8/10A wrought magnesium alloy with the highest strength of the common AZ grades: it machines like a harder aluminium and holds a better finished surface than the casting grades.
AZ91E
8/10The sand-casting version of AZ91 with a high-purity specification: lower strength than the die-cast grade but a far lower casting cost for low volumes, and it machines the same way.