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A super-hard metal has been made in the laboratory by melting together titanium and gold.
The alloy is the hardest known metallic substance compatible with living tissues, say US physicists.
The material is four times harder than pure titanium and has applications in making longer-lasting medical implants, they say.
Conventional knee and hip implants have to be replaced after about 10 years due to wear and tear.
Details of the new metal - an alloy of gold and titanium - are revealed in the journal, Science Advances.
Prof Emilia Morosan, of Rice University, Houston, said her team had made the discovery while working on unconventional magnets made from titanium and gold.
The new materials needed to be made into powders to check their purity, but beta-Ti3Au, as it is known, was too tough to be ground in a diamond-coated mortar and pestle.
The material "showed the highest hardness of all Ti-Au [titanium-gold] alloys and compounds, but also compared to many other engineering alloys", said Prof Morosan.
She said the hardness of the substance, together with its higher biocompatibility, made it a "next generation compound for substantively extending the lifetime of dental implants and replacement joints".
Source: http://www.bbc.com/news/science-environment-36855705
(Score: 4, Informative) by richtopia on Monday July 25 2016, @05:57PM
I'm jealous that you were given that titanium. If anyone wants some experience working with titanium, you can buy small sheets on ebay. A bit too expensive for much more than specialized parts.
http://www.ebay.com/itm/3mm-Thick-Titanium-6al-4v-Sheet-125-x-6-x-6-Grade-5-Plate-Ti-Gr5-Metal-/221999403553?hash=item33b0321221:g:iRUAAOSwqYBWnf8d [ebay.com]
If you have a laser etcher titanium is fun to mark.
In regards to the USSR, yes, there was a lot of titanium. The CIA had to form a bunch of shell companies to buy enough titanium for the SR71. And the Guggenheim Museum Bilbao was clad in titanium only because it was built in 1991 - the titanium market was flooded with metal from Russia then.
(Score: 5, Informative) by DECbot on Monday July 25 2016, @06:49PM
Also to note, if you're welding titanium, it must be done in an inert atmosphere (100% argon, no humidity). Additionally, you need to reduce the heat input as the heat affected zone around the weld will become very brittle. That pretty much leaves you with TIG, Plasma, or specialty MIG processes like CMT. As for laser, I'm not so sure as there's lots of heat input, but the heat affect zone is typically smaller.
cats~$ sudo chown -R us /home/base
(Score: 3, Interesting) by DECbot on Tuesday July 26 2016, @12:26AM
I thought on this a little more.... By no means am I a weld engineer or materials engineer, but I did some quick references to see the feasibility of welding this new alloy. Gold has a melting point of 1064°C and a boiling point of 2700°C while titanium melts at 1668°C and boils and temperatures higher than I care about for this thought problem (in excess of 5900°C for those curious folks). When welding this alloy, you're likely to hit the boiling point of the gold during the weld and due to the low melting point of the gold. This will result in gold vapor escaping from the base material and cause expulsions, spatter, and porosity in the weld. AKA a really bad weld. Imagine making a knee replacement, and right where the tendon goes over the weldment, there is a tiny 0.5mm ball of spatter rubbing against the tendon than no regular grinding disk could remove. You would essentially feel a tiny knife slowly cutting your tendon every time it moves over this spatter ball. So the process window for welding is very tiny and the process to remove spatter and bad welds very expensive. Now the article [sciencemag.org] does mention that the intermetallic TiAu alloys have lower melting point than Ti, but no details were listed in the article and I wasn't bothered to look up the referred article (footnote 64 [sciencemag.org] for those with more determination than I). Perhaps the process window is greater than I'm imagining. However, if your goal in life is to avoid the spatter completely, you could try brazing--where you melt the gold to your filler metal, but never melt the titanium. This will make a strong bond, but it won't be as strong as the base material. Here at least the spatter would be cheap to remove (well, as cheap as grinding gold away--I mean what's the inherent value of gold dust?) and the brazes easy to cut out if needed. In regards to melting, the only thing I saw the article suggest is casting, frankly due to the machining costs. Less face it, machining something harder than most industrial grinding an milling tools and the value of the dust is likely worth more per pound than the person machining the final product really detracts from the possibility of becoming a viable industrial process.
Again, I'm not an expert, but I happen to work with some experts. Correct me if you have insight that I may be ignorant of.
cats~$ sudo chown -R us /home/base
(Score: 2) by butthurt on Tuesday July 26 2016, @02:57AM
I don't know much about metallurgy, but I think sintering (fusing metallic powder) might lend itself to the manufacturing of implants. It allows creation of porous metal bodies. Living tissues could grow into the pores in an implant. I would assume people are using sintering for that purpose already.
https://en.wikipedia.org/wiki/Sintering [wikipedia.org]
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @07:38AM
Gold has a melting point of 1064°C and a boiling point of 2700°C while titanium melts at 1668°C and boils and temperatures ...
Oh come on, it's over 1000°C of margin for both of them to remain in liquid phase!
(Score: 2) by LoRdTAW on Tuesday July 26 2016, @01:36PM
We weld titanium all the time using pulsed NdYAG in an open air machine using nozzle delivered 100% argon shield gas. And yes, these are medical parts. However, we are running a job welding titanium heart pumps in a glove box. But only because the shape of the part makes nozzle delivered gas coverage difficult. Otherwise that would be welded in a standard open air machine.
Electron beam is another process we use for titanium. Mainly aerospace titanium parts are EB welded with some medical parts here and there with deep penetration requirements or some crazy engineer specs it out.
The biggest worry with titanium parts with a finish: fingerprints. They will never come out once imparted. So we must handle them with gloves.
(Score: 2) by DECbot on Tuesday July 26 2016, @03:16PM
Most of the Ti welding I've seen is aerospace. However I once saw a weld trial for golf clubs.
Anyway, how do you handle backside shielding for your open air application? Is it open root and you're getting enough argon to the backside or is it just partial penetration for something like a fillet weld?
cats~$ sudo chown -R us /home/base
(Score: 2) by LoRdTAW on Tuesday July 26 2016, @08:01PM
Just about all titanium medical device laser jobs are partial pen. Mainly butt and fillet type welds to secure pins or tool to a handle/shaft. Very easy to weld on an XY table or rotary. The heart pump job was an example of a partial pen job that has difficult geometry to easily shield. So we just stuck it in a glove box and called it a day.
The electron beam stuff is where the fun begins. Full pen welds up to two inches deep with a bead width of only ~0.2 inches. And since it's in a vacuum, shield gas is a non issue. Though only a hand full of our Ti medical jobs are EB. Usually you get an engineer from a med device company who hears about EB, gets all excited, and then learns the cost difference.
(Score: 2) by bzipitidoo on Monday July 25 2016, @08:21PM
I got a set of titanium eating utensils, partly out of curiosity and partly in hopes I could persuade my significant other to ditch the plastic she prefers over stainless steel. Quit wasting money on plastic. I wondered if her objection to stainless steel and love of plastic might be simply the weight. The latter hope was only partly realized.
They're very expensive, about $20 for one spoon, fork, and knife. Titanium makes for a good combination of lightweight yet strong, and corrosion resistant and non-toxic. Quite a few brands of titanium utensils. They make them for camping, going for the lightest possible weight. Designed them as slim as they could. I checked. There's a fair bit of variation, but a typical spoon is about 25g in stainless steel, 17g in titanium, and 6g in plastic.
One bad property is the marks the titanium knife leaves in ceramic plates if you aren't careful and saw at food a little too enthusiastically. While it doesn't make a scratch that can be felt, it leaves a silvery mark that just will not come out. Need a light touch to avoid that.
(Score: 2) by t-3 on Tuesday July 26 2016, @01:09AM
Personally, I hate the metal taste of steel silverware.
(Score: 0) by Anonymous Coward on Tuesday July 26 2016, @07:07AM
Have you tried to remove the marks with an acid?
(Score: 2) by Aiwendil on Tuesday July 26 2016, @08:01AM
Just thinking out of the box - but have you tried introducing her to chopsticks? (I prefer them over forks simply because they have a much nicer motion for the hand)
Or for that matter - tried utensils with a different material in the handle? I grew up with utensils with bakelite handles and still prefers them - unless the utensils are properly weighted. (When I switched to all steel utensils it took me feeling about 40 different designs before I found a comfortable set - I want my forks insanely light and my knives with their center of gravity outside the cutting area (my current knives naturally falls "backwards" when I relax my hands - thereby reducing effort to handle then))
Yes, I often eat western food with chopsticks and knife.