
On Friday, I wrote about the development of amorphous or “glassy” metal alloys, in which the atoms are packed together with no regular crystal structure. At the microscopic level, almost all metals are made of crystal grains, which can be bigger or smaller depending on how the metal has been heat treated. Amorphous alloys, recall, are extremely unusual among metals because they can be cast without forming crystal grains at all.
At the opposite end of the spectrum are single crystal (SC or SX) alloys, which are mixtures of metals that can be cast in such a way that the entire object is essentially a single giant “grain,” i.e. one continuous crystal. Among minerals like quartz, large objects composed of a single crystal are fairly common; you also may have seen the large ingots of artificially-grown single-crystal silicon, known as “boules,” from which wafers are cut to make microchips and other semiconductor devices.
But when it comes to metals, single-crystal objects are outside of most people’s experience. Forming single-crystal metal objects requires both special alloys and special casting techniques. The alloys are almost always nickel-based, with as many as nine minor metal components including five or more percent chromium, cobalt, tungsten, tantalum, aluminum, and/or rhenium. The casting method is known as “directional solidification,” and involves carefully cooling a cast metal part starting at one end to guarantee a particular orientation of its crystal structure. That orientation is chosen, naturally, based on expected stresses in the finished part.
The primary application for single crystal superalloys is the manufacture of jet engine turbine blades, which must endure tremendous forces at extremely high temperatures for prolonged periods of time. Under such conditions, metals with a grain structure tend to “creep,” or slowly deform, along grain boundaries. Because single-crystal alloy parts have no grain boundaries, however, they are highly resistant to this kind of wear.
If you’re interested in reading more, check out the excellent online primer on nickel-based superalloy technology maintained by The University of Cambridge’s Dr. Harry Bhadeshia.
25 thoughts on “Single Crystal Superalloys”
Comments are closed.
Someday, I want to be SMR smrt…
I was actually given one of these turbine blades when I was visiting an air-force base (it was a “dead” one, removed from an engine during overhaul). The tech’s spent a wee while explaining the process in creating them, and that they are single-cyrtal metals…
Fascinating stuff, and I have a piece of single-crystal metal as a souvenir! I’d almost forgotten about it until I saw that previous post and dug it out…
I don’t know, it’s probably a burden being that smart. You have to suffer the likes of dumb guys like us.
[…] MAKE | Single Crystal Superalloys At the opposite end of the spectrum are single crystal (SC or SX) alloys , which are mixtures of metals that can be cast in such a way that the entire object is essentially a single giant “grain,” i.e. one continuous crystal. […]
[…] Single Crystal Superalloys […]
[…] Single Crystal Superalloys […]
titanium oxides is only malleable,when it’s free of oxygen.
testme
[…]here are some links to sites that we link to simply because we consider they may be really worth visiting[…]
testhim
[…]we prefer to honor quite a few other world wide web internet sites around the internet, even when they arent linked to us, by linking to them. Underneath are some webpages really worth checking out[…]
findme
[…]please go to the web sites we adhere to, like this a single, as it represents our picks from the web[…]
israel trip
[…]Every as soon as in a whilst we pick blogs that we read. Listed below are the most current websites that we pick […]
FCATalk
[…]below you?ll discover the link to some internet sites that we feel you need to visit[…]
oxandrolone
[…]Here are a few of the web-sites we advise for our visitors[…]
Professional ghostwriter
[…]here are some hyperlinks to web pages that we link to for the reason that we believe they may be worth visiting[…]
torticollis treatment at home
[…]always a significant fan of linking to bloggers that I adore but do not get a lot of link adore from[…]
Promote skin products online
[…]Sites of interest we have a link to[…]
protect
[…]one of our guests lately encouraged the following website[…]
123employee
[…]Every when in a although we pick out blogs that we study. Listed below are the latest web sites that we pick out […]
Hooke
[…]The information and facts talked about inside the report are several of the best obtainable […]
avocat drept comercial iasi
[…]the time to study or visit the subject material or web sites we have linked to below the[…]
Joseph Ioia
[…]always a major fan of linking to bloggers that I enjoy but don?t get a lot of link enjoy from[…]
home computer repairs
[…]we like to honor quite a few other world wide web sites around the net, even if they aren?t linked to us, by linking to them. Underneath are some webpages really worth checking out[…]
[…] EDF’s gas turbine during production in Belfort. Above: Blades made from superalloy monocrystals help the HA turbine manage temperatures as high as 2,900 degrees Fahrenheit and extract more […]
[…] EDF’s gas turbine during production in Belfort. Above: Blades made from superalloy monocrystals help the HA turbine manage temperatures as high as 2,900 degrees Fahrenheit and extract more […]
[…] has turbine blades made from superalloy monocrystals to manage temperatures as high as 2,900 degrees Fahrenheit. It also has variable stator vanes (the […]