Effect of Adding Rare Earth on Cast Magnesium Alloy
by Julissa G. Content generatorThe application of Magnesium Alloy has
been rapidly developed since 1950s when rare earth metals were used as alloying
addictives. The addition of rare earth metals in magnesium alloys greatly improves
the creep resistance, the strength properties both at room temperatures and
elevated temperatures and the castability of Magnesium Alloy.
Below are three types of magnesium alloys
containing rare earth metals:
1.
Mg-RE-Zr
Alloy
Mg-RE-Zr (Mg-3RE-0.1Zr) Alloy
is widely used in aero-engines due to its high strength properties and good
creep resistance at 205℃.
2. RE
Mg-Zn-Zr Alloy
ZK51 (Mg-4.5Zn-0.6Zr) has a tensile strength
of 280MPa, but its castability is poor. However, the addition of RE will
greatly improve the castability because the Mg-Zn-RE compounds which appear
after adding RE will be distributed over the grain boundary in
the form of divorced eutectic.
ZE63A (Zn-6wt%, RE-2.5wt%, Zr-0.6wt%) has
been applied in the thrust reversal of RB211 engine for years. It has a tensile
strength of 276MPa, a yield strength of 186MPa and a ductility of 5%.
3.
Y-Mg
Alloy
Yttrium has a good solution strengthening
effect on Magnesium Alloy, which results from the blocking of yttrium solution
by heat-resistant compounds in matrix and grain boundary. Therefore, Y-Mg Alloy
has good thermal strength properties and even has the same elevated temperature
property as Thorium-Magnesium alloys. Moreover, Yttrium-Magnesium Alloy also
possesses excellent high temperature oxidation
resistance. Magnesium Alloy containing 9 wt% Yttrium only gained
a weight of 1 mg after being heated to 510℃in moist air and
kept for 98 hours while Thorium-Magnesium Alloy gained a weight of 15 mg.
Information provided by Stanford Advanced Materials.
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Created on Jun 11th 2019 03:50. Viewed 499 times.