Elektron® RZ5

Elektron® RZ5 is a  proven magnesium casting alloy containing zinc, rare earths and zirconium. Used in the T5 condition, this high strength magnesium alloy is ideal for high integrity castings operating at ambient temperatures of up to 150˚C. In addition to displaying excellent casting characteristics, the alloy is both pressure tight and weldable.

The versatility of this alloy makes it of interest to a wide range of designers dealing with aerospace, automotive, military and electronic applications. Castings in Elektron® RZ5 are found in a wide range of applications including:

  • Helicopter gearboxes
  • Performance car components
  • Video cameras
  • Military equipment
  • Computer parts
  • Aircraft engines
  • Power tools
  • Vibration testing equipment
  • Aircraft components
  • Motorcycle wheels

ASTM B80 ZE41A-T5 AMS 4439
UNS M16410
BS2970 MAG5-TE AIR 3380 RZ5
AFNOR G-Z4TR DIN 1729 3.5101
Aircraft Number 3.6104 UNAVIA 816-02 EN 1753
EN MB 35110

Zinc:   3.5–5.0%
Rare earths:   0.8–1.7%
Zirconium:   0.4–1.0%
Magnesium:   Balance

Optimum properties are achieved in the T5 condition after 2 hours at 330˚C followed by 10–16 hours at 170–180˚C. Water quenching is not required. Satisfactory properties may be obtained from 1–6 hours at 325–360˚C. Water quenching is not required.

Specific gravity:   1.84
Coefficient of thermal expansion:   27.1x 10-6K-1
Thermal conductivity:   109 Wm-1K-1
Specific heat:   960 Jkg-1K-1
Electrical resistivity:   68 nΩm
Modulus of elasticity:   44.1 GPa
Poissons ratio:   0.35
Melting range:   510–640˚C
Damping index:   1.0
Brinell hardness:   55–70

Minimum specification tensile properties
BS 2L.128
0.2% proof stress:   135 MPa
Tensile strength:   200 MPa


Good. Castings will contain minimal microporosity and the tendency to hot cracking is low. Castings are pressure tight and may be welded.

Pattern makers shrinkage factor



Weldable by the tungsten arc inert gas process (TIG) with a filler rod of a similar composition. Castings should be heat treated after welding.


Elektron® RZ5 castings, like all magnesium alloy castings, machine faster than any other metal. Providing the geometry of the part allows, the limiting factor is the power and speed of the machine rather than the quality of the tool material. The power required per cubic centimetre of metal removed varies from 9 to 14 watts per minute depending on the operation.

Surface treatment

All the normal chromating, anodising and finishing treatments are applicable.

Corrosion resistance

ASTM B117 Salt spray test
Corrosion rate:   4–6mg/cm2/day

Low temperature properties

Mechanical properties at -196˚C:
Elongation:   0.5%
Ultimate tensile strength:   245MPa
Impact value (unnotched):   0.7j

Typical tensile properties

0.2% proof stress:   148 MPa
Tensile strength:   218 MPa
Elongation:   4.5%

Typical compressive properties

0.2% proof stress:   130–150 MPa
Ultimate strength:   330–365 MPa

Typical shear properties

Ultimate stress:   138 MPa

Fracture toughness

KIC:   15.1–16.3 MPa m1/2

Fatigue properties

Figure 1. Rotating bending fatigue tests on sand castings.

Figure 2. Fatigue crack growth.

Typical tensile properties

Figure 3. Effect of temperature on tensile properties.

Creep properties

Figure 4. Stress / time relationship for specified creep strains at 100˚C.

Figure 5. Stress / time relationship for specified creep strains at 150˚C

Fatigue properties

Figure 6. Rotating bending fatigue tests.

Table 1. Cut up properties on samples taken from actual castings.

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Ross Baird

Sector Manager Aerospace Advanced Castings