Naked Science Forum

Non Life Sciences => Technology => Topic started by: thedoc on 22/05/2012 18:04:50

Title: Are rare earth elements used in alloys?
Post by: thedoc on 22/05/2012 18:04:50

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

Asked by Cedrick Meriman, SecondLife


                                        Visit the webpage for the podcast in which this question is answered. (http://www.thenakedscientists.com/HTML/podcasts/show/20120520/)

 

Title: Are rare earth elements used in alloys?
Post by: thedoc on 22/05/2012 18:04:50

We answered this question on the show...



Nick -   Rare earth elements are just a certain part of the periodic table.  It’s 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, it’s 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.

Title: Re: Are rare earth elements used in alloys?
Post by: CliffordK on 22/05/2012 20:42:13

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.

Title: Re: Are rare earth elements used in alloys?
Post by: Bored chemist on 22/05/2012 21:15:47

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) (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.