Adding gold vastly increases strength and hardness. I’d still prefer just regrowing the standard body parts, though.
I wonder what aerospace applications it might have?
24 thoughts on “A New Titanium Alloy”
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Adding gold vastly increases strength and hardness. I’d still prefer just regrowing the standard body parts, though.
I wonder what aerospace applications it might have?
Comments are closed.
Does it have good temperature resistance? Does not sound like it from the base materials but the crystalline form may dissipate heat better.
I guess you could use it for internal spaceship structures, not exposed to heat, much like they used Al in the Shuttle. Perhaps some fuel tanks as well? Those usually made with composites.
This looks like a possible replacement for composites.
Shuttle used a lot of aluminum, but primary structure (spar, keel) was titanium.
I didn’t know they used Titanium in the Shuttle. I think I read in some place that Titanium loses strength at relatively low temperatures so it isn’t good for high temperature applications either. So they used Aluminium because it was cheaper. Interesting to know. The article about Ti-3 mentions hardness, so perhaps it doesn’t have that much tensile strength though. It mentions nothing about that.
For fuel tanks and internal structures you would want tensile strength and some stiffness rather than hardness.
The spar and keel were never supposed to see high temperatures. They were protected by the tiles. In theory.
Titanium alloys we used in the A-12 / SR-71 specifically because of their favorable strength characteristics at elevated temps.
Yeah but that’s at Mach 3 not reentry speeds. Plus IIRC the SR-71 was full of fuel close to the skin of the plane.
I was rebutting your specific statement “…Titanium loses strength at relatively low temperatures…”. I fail to see how your reply to me is relevant to your original comment or my reply :-/
Godzilla, it’s not just the speed. Duration, heat shield, attached shock wave vs. detached, make a big difference for heat inflow to the structure.
And of course the highest reentry temperature parts of the Shuttle used LTV’s reinforced carbon-carbon as the thermal protection.
Actually, the shuttle has very little titanium – it’s really limited to the thrust structure. The major reason for this is to do with thermal conductivity. Titanium has high temperature capability but low thermal conductivity for a metal. Hot spots would have a tendency to concentrate and burn through, rather than an aluminum design, where they’d be more likely to spread out. The difference in weight, when this and other factors were considered, proved to be minimal.
Well, for a generous definition of “thrust structure.” My dim recollection, as a former employee of the prime contractor, was that it was primarily for keel and spar. Which is (I agree) pretty minimal use. OTOH, those were a key element of the “structural spares” that allowed Endeavour to be built after the loss of Challenger.
IIRC in the original Shuttle design proposals it was to be built of
rene 41/inconel/some other nickel-chromium super-alloy. I have heard the design was changed to aluminium structure and ceramic tiles later. The reasons why the design was changed were supposedly: a) the new design was cheaper, b) the reentry temperatures in the vehicle were higher than originally expected. I do not know the exact reason why the design was changed though.
Back when Shuttle was supposed to be a real TSTO:
http://www.pmview.com/spaceodysseytwo/spacelvs/sld029.htm
“IIRC in the original Shuttle design proposals it was to be built of
rene 41/inconel/some other nickel-chromium super-alloy. I have heard the design was changed to aluminium structure and ceramic tiles later.”
Your remarks remind me about the Rockwell X-30:
“Temperatures on the airframe were expected to be 980 °C (1800 °F) over a large part of the surface, with maxima of more than 1650 °C (3000 °F) on the leading edges and portions of the engine. This required the development of high temperature lightweight materials, including alloys of titanium and aluminum known as gamma and alpha titanium aluminide, advanced carbon/carbon composites, and titanium metal matrix composite (TMC) with silicon carbide fibers. Titanium matrix composites were used by McDonnell Douglas to create a representative fuselage section called “Task D”. The Task D test article was four feet high by eight feet wide by eight feet long. A carbon/epoxy cryogenic hydrogen tank was integrated with the fuselage section and the whole assembly, including volatile and combustible hydrogen, was successfully tested with mechanical loads and a temperature of 820 °C (1500 °F) in 1992, just before program cancellation”
https://en.wikipedia.org/wiki/Rockwell_X-30
Breaks my heart that it was cancelled; Oh well maybe it did continue as some kind of a black box project. Maybe the developed tech was rolled into the rumored Aurora spy plane.
https://en.wikipedia.org/wiki/Aurora_(aircraft)
AFAIK there were a lot of issues with the metal matrix composites kind of akin to the issues they had with the XB-70 Valkyrie.
The materials weren’t quite there yet and a more conservative design back then would have probably been a better idea.
Al-Li fuel tanks are for all intents and purposes good enough and proven to work. Carbon composite tanks can also work as long as you keep the design simple and have robust quality control. I think there’s room for further incremental improvements in propulsion technology but yeah someone needs to figure out how the structures once we move to full reusability so that the turn-around time is smaller. So far SpaceX hasn’t reused anything yet. Even if they managed to recover several vehicles by now. At least the recovered vehicles should be providing them with good data to design their next vehicles. Falcon-9 V1.2 supposedly already includes a lot of design changes.
My main problem with this stuff, at least with respect to aerospace applications, is its probable density. The article says the stuff is three parts titanium and one part gold. If you multiply the density of titanium by 3, add the density of gold and divide the whole thing by 4 you get a density figure roughly midway between that of iron and nickel or cobalt. Unless this stuff has some thermal or mechanical figure of merit that is way off the charts relative to existing titanium or ferrous superalloys, I don’t think aerospace is going to find any use for it at all. And that’s without even considering the cost.
For medical implant applications it may prove a game changer. Medical implants are tiny by the standards of aerospace structural parts and they don’t weigh very much either. Also, they are usually custom made and very pricey anyway. If this stuff allows fabrication of, say, artificial hip or knee joints with a multi-decade lifespan instead of the current 15 – 20 years, that would be a real step forward.
As a “wonder material” for aerospace applications, though, I’m very dubious.
The article gives the link to the full paper which is available for free by Open Access (which all academic papers SHOULD be by the way.)
The density with the addition of gold is about that of steel, twice what titanium alone is. But the article doesn’t give the yield strength.
But I found a paper on Arxiv by the same team which does give the yield strength:
Ti1−xAux Alloys: Hard Biocompatible Metals and Their Possible Applications.
“The search for new hard materials is often challenging from both theoretical and experimental points of view. Furthermore, using materials for biomedical applications calls for alloys with high biocompatibility which are even more sparse. The Ti1−xAux (0.22≤x≤0.8) exhibit extreme hardness and strength values, elevated melting temperatures (compared to those of constituent elements), reduced density compared to Au, high malleability, bulk metallicity, high biocompatibility, low wear, reduced friction, potentially high radio opacity, as well as osseointegration. All these properties render the Ti1−xAux alloys particularly useful for orthopedic, dental, and prosthetic applications, where they could be used as both permanent and temporary components. Additionally, the ability of Ti1−xAux alloys to adhere to ceramic parts could reduce the weight and cost of these components.”
https://arxiv.org/abs/1410.7308
It gives the yield strength as 2.65 GPa (gigapascals). This is better than standard stainless steel. But there are some specialized steel alloys at about this strength. As I recall these specialized grades have restrictions on them because their high strength allows their use in nuclear processing centrifuges.
Bob Clark
Gold titanium alloy? Tony Stark approves.
Thanks for the post, Rand. Our F-14 Tomcat had a titanium box linking the variable geometry wings. The Boeing SST was planned to be built of Ti. The movie’s IRON MAN was built of a gold-titanium alloy!
I am sad. 33% Gold? Too expensive and too heavy for bicycle components. Sigh. I am forced to stick with my clunky old carbon fiber and Ti parts.
(But I have visions of this alloy being the “new thing” for ultra upscale wristwatches, scuba dive knives, and iPad chassis.)
My old man test-flew Concorde for US certification. Later, when the B-1 was proposed, he claimed that all of the B-1 missions, except low-level supersonic penetration, could be flown with a Concorde-based design. And even THAT mission was flyable if you were willing to sacrifice the airframe (heat on aluminum) after one mission.
Never analysed this idea, but seemed intriguing.
(He loved Concorde. Of all the very many aircraft he flew, it was his favorite.)
I’m sure it was fun to fly, but it was not a practical aircraft for public transportation.
On reflection, I don’t think anything he flew was practical for public transport, with the DC-3 as the sole exception.
Just an engineering rule of thumb.
Ti has 80% strength at 400°F, and half strength at 1000°F.
Stainless has 80% strength at 800°F, and 50% at 1000°F
Al has 80% strength at 350°F, and half strength at 400°F.
In other words;
– If your heat loads are above 1000°F, you had best get a thermal engineer to hold your hand. You will probably need a super alloy, ceramic or ablative.
– Stainless is good for most hot things
– Ti light weight but you have to be careful what you are doing.
– Aluminum turns to playdough above about 350°F. If you have to think about thermal loads: Do NOT use unless your Thermal guy says it’s ok.
Take that with a gain of salt, as these alloys can vary a lot.
See also MMPDS-8 chapter 6 (the new Mil Handbook 5)
As was stated above. Density and cost kills it for aero use. We can already get a fairly high strength steel at those densities for cheaper. However it might be useful for the navy as it should be good in salt water environments. Maybe use for a bathysphere?