Science Questions

Are rare earth elements used in alloys?

Sat, 19th May 2012

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Question

Cedrick Meriman, SecondLife asked:

Do rare earth metals get used in alloys? Given their high price, Id assume not.

 

Answer

Nick -   Rare earth elements are just a certain part of the periodic table.  Its just a group of elements and some of them, such as Yttrium and Lanthanum, do find some small percentage uses in some modern alloys but as you say, there's no large scale use of them, just due to their high cost.

Ben -   Roger, when you're designing new alloys or when you're modelling them, do you work around the cost?  Are there ways that you can replace things that rare earth elements would otherwise do?

Roger -   Yes, its certainly true that we consider the cost because certain elements, like rhenium for example in turbine blade alloys, are now very expensive, several thousand pounds per kilogram.  When one is interested in building a jet engine with perhaps 100 blades per row then the cost can become significant quite quickly.  So certainly, there are calculations done to trade off the relative benefits of elements like rhenium and tungsten, and molybdenum and other refractory metals against their disadvantages which are then costs and also their scarcity.

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Gold has been used in alloys for eons.

The "Rare Earth Magnets" are an alloy too, for example NdFeB (Nd2Fe14B) magnets are a Neodymium alloy.

Good point about the strength and weight properties of many exotic alloys. 

Like the high melting point alloys used an aircraft engines, there are also low melting point alloys used in solders and heat detectors in sprinkler systems, using metals such as Antimony, Bismuth, Cadmium, Lead, Tin, Indium, Gallium, and Mercury.
CliffordK, Tue, 22nd May 2012

OK, so in a thread about the rare earth metals reference is made to about 16 elements of which just 3 are actually rare earth metals.

The rare earth metals are not  (as a group) all that rare.
Estimates vary
http://en.wikipedia.org/wiki/Abundances_of_the_elements_(data_page)
but (apart from the radioactively unstable one) they are all commoner than silver. The commonest  (cerium) is less rare than copper, zinc or nickel.
I'm fairly sure that they are seldom used as pure metals so, to they extent that the metals are used at all, they are used in alloys.

Probably the most widespread use is in the "flints" of cigarette lighters.
Bored chemist, Tue, 22nd May 2012

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