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Super-hard metal 'four times tougher than titanium'
- tsomctl 10y ago> Titanium is one of the few metals that human bone is able to grow around firmly, allowing it to be used widely in medicine and dentistry. How good are we at concentration gradients in alloys? For a replacement joint, say, could the part that the bone bonds to be mostly titanium, and then the bearing portion be this new alloy?
- GarrisonPrime 10y agoAlthough I've only spent a few weeks in an ortho rotation in med school, I think pretty good. Many implants are coated with silver to help prevent infections. I've never heard of such silver layers ever "peeling off" or somesuch, so it seems the silver/titanium mix is effective.
- Roboprog 10y agoThe silver oxidizes and disappears after a while (few weeks?) though, right? (probably by design)
- maxerickson 10y agoThe article says the material has better biocompatibility than currently used alloys, so biocompatibility wouldn't be a motivation to do that. Still have to think about other measures of strength and the processes required to make parts out of it. More: The paper mentions bonding the material to the surface of ceramic materials to save weight.
- clinth 10y agoIt's been quite a long time since I studied this, but the primary problem with materials in implants is the quality of being bioinert. Many titanium alloys are not bioinert. Any combination would have to be tested separately.
- lj3 10y agoThis. Anytime you have metal in the body, you want to make sure it's not going to leach into the bloodstream and cause heavy metal toxicity, like mercury or amalgam fillings do.
- pkroll 10y agoGonna need a link for that. Here's one: http://www.quackwatch.com/01QuackeryRelatedTopics/mercury.html http://www.quackwatch.com/01QuackeryRelatedTopics/mercury.ht...
- clinth 10y agoMercury/amalgram fillings isn't the best example, but biocompatibility is still the primary constraint. Mayo clinic has a good overview and timeline regarding the discovery process for cobalt-chromium, which was previously thought to be a good all-around implant material: https://medlineplus.gov/ency/article/002495.htm https://medlineplus.gov/ency/article/002495.htm
- woliveirajr 10y agoNot only leach. Even titanium alloys used in implants have narrow specifications. For example, the Ti6Al4V that is used in implants differs from the used in airplanes by the amount of Iron on it. From 0.05% to 0.5% makes your body react to it and reject the implant.
- valarauca1 10y agoLink to paper http://advances.sciencemag.org/content/2/7/e1600319 http://advances.sciencemag.org/content/2/7/e1600319 Link to PDF of paper http://advances.sciencemag.org/content/advances/2/7/e1600319.full.pdf http://advances.sciencemag.org/content/advances/2/7/e1600319...
- amluto 10y agoThe BBC article heavily confuses hardness and toughness. The researchers seem to care about hardness here. The actual paper (http://advances.sciencemag.org/content/2/7/e1600319.full http://advances.sciencemag.org/content/2/7/e1600319.full) is much better and is free.
- pcl 10y agoToughness is a new term for me. From [1]: Hardness is a characteristic of a solid material expressing its resistance to permanent deformation. The Rockwell or Vickers hardness scales are most commonly used in the industrial blade industry. Toughness on the other hand is the maximum amount of energy a material can absorb before fracturing, which is different than the amount of force that can be applied. Toughness tends to be small for brittle materials, because it is elastic and plastic deformations that allow materials to absorb large amounts of energy. [1] http://americancuttingedge.com/hardness-vs-toughness/ http://americancuttingedge.com/hardness-vs-toughness/
- dexwiz 10y agoThere are several material property terms that get mixed around when converting to layman's. Toughness and hardness are two of them. Another set is Plasticity and Elasticity which measure tension properties. Elasticity is how much you can deform (stretch) an object, before the deformation is no longer reversible. Think of a rubber band, you can stretch it a little, and it returns to its original shape. Stretch it a lot, and it breaks down and does not return to its original shape. Plasticity is how much you can deform an object before it breaks. This is the snapping point in the rubber band, where it completely breaks. These two properties are different, and have to do with how the material is deforming on an atomic level. During elastic deformation, the individual bonds stretch. During plastic deformation, regions, layers, or fibers of the material slip. The relationship is best described by the stress-strain curve [1]. This plots deformation versus the pressure required. Hardness and Toughness are the compression version of Elasticity and Plasticity. These properties are often found experimentally, because they are a summation of many different atomic level interactions. Infact most materials are anisotropic, meaning if I measured the toughness of a material along two axises, I would get two different values. [1] https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve
- mbrumlow 10y agoI was a bit frustrated by this title.
- tomrod 10y agoI'm always interested in feedback about titles because I feel I do them poorly (I'm not OP). What do you find frustrating about the title?
- DanBC 10y agoI read it and I didn't know if BBC meant "hard but brittle" or something else.
- honkhonkpants 10y agoProbably that it uses the common definition of toughness an article about metallurgy while metallurgy has a special definition of that word.
- VLM 10y agoEven worse, using real metallurgy words, titanium is really strong per volume and doesn't care about high heat and is practically corrosion proof and a couple other weird properties... ironically what its NOT known for is its rather pedestrian hardness and toughness specs. There's a lot of reasons to talk up titanium and they carefully sidestepped around each of them LOL in favor of talking up two things titanium is fairly worthless at (at least worthless at per dollar or whatever). If you want something tough that can absorb surprising amounts of energy without breaking there are exotic nickel steels that require exotic heat treatment, or maybe some of the military armor plates from the old days (before HEAT rounds forced other criteria as a figure of merit). Maybe a chunk of battleship armor plate or maybe the crankshaft from an old diesel ship engine. If you want something hard there are some oxidized titanium coatings that are somewhat hard and industrially useful but nothing unusual or worth writing home about. Besides that's cheating because its a titanium containing compound, kinda like saying coal cures scurvy because vit C is merely a peculiar arrangement of carbon atoms much like coal. Industrial diamonds are not going to be replaced by titanium rod anytime soon...
- ftwtitanium 10y agoAn alloy of gold and titanium? Iron Man anyone?
- sevenless 10y agoWith the bio-compatibility, it'd work better for Wolverine.
- Roboprog 10y agoWell, titanium has a a lot of strength relative to its weight, but I think you might need some kind of tungsten alloy for your budding weapon X program :-) I have no idea how toxic tungsten is, buy hey, it's Wolverine, right?
- andrewflnr 10y agoSeriously wondering if I'm still in the real world.
- deleted 10y ago[deleted]
- greydius 10y agoFinally, someone has found a good use for gold other than ridiculously overpriced a/v cables.
- jfoutz 10y agoAnd processor interconnects.
- avs733 10y agoand reflective heat coatings (...and jewelry)
- stephengillie 10y agoAnd plumbing.
- avs733 10y agoI forgot about trump...
- kragen 10y agoAnd corrosion-resistant contacts of all kinds, and soft and biocompatible and corrosion-resistant tooth fillings, and low-resistance conductors (e.g. for bond wires), and coating glass to get ultra-low-loss mirrors well into the infrared, and measuring electrical charge in electroscopes, and coloring glass deep red, and conductive sheets so thin they are transparent, and in anti-inflammatories for arthritis, and in immunogold labeling, and in making random things conductive and emit lots of secondary electrons so you can easily look at them in an electron microscope... This is why you're being downvoted. Check Wikipedia before commenting next time.
- greydius 10y agoIt was meant to be tongue-in-cheek. Gold has some nice useful properties, but it seems the properties that have mattered most to people throughout the millenia are 1) it has a pleasing color, and 2) it's hard to come by.
- scentoni 10y agoSince it's 58% gold by weight, just the raw materials cost is going to be high. I expect for most applications it will be used as a thin coating over titanium or some other material. I wonder if it's a good choice for jewelry. Phase diagram: http://www.himikatus.ru/art/phase-diagr1/Au-Ti.gif http://www.himikatus.ru/art/phase-diagr1/Au-Ti.gif
- avs733 10y agoAfter the long discussion in the 'alcohol causes cancer' thread I will admit to being a bit suspicious of science journalism.
- stephengillie 10y ago"Does the study have at least 10^4 subjects?" That's the first thing I check.
- Turing_Machine 10y agoJust now? :-) Seriously, science journalism is almost uniformly horrible (as is just about every other type of journalism -- google "Gell-Mann Amnesia Effect").
- avs733 10y agoI would disagree with the 'almost uniformly' but I understand your point. I would tend to exempt arstechnica for example. I feel like most of the issue comes when journalists comment or repurpose journal articles. What seems to get dropped is the background, the context, and the limitations that are often expressed in a nuanced language. In the end, as a scientist, I blame scientists...you created the knowledge, try and take some ownership of it (having been in the situation myself).
- andyidsinga 10y ago"Conventional knee and hip implants have to be replaced after about 10 years due to wear and tear." this is really amazing to me! you put metallic, designed-to-last object inside an organic blend of tissue and bone and human activity and in 10 years its worn out. So much opportunity in the area! Along the same lines, interesting how delicate our bodies are in the short term but rather durable in the long term.
- Aelinsaar 10y agoYour own body basically goes through a skeleton every 7 years, although it's a gradual procedure of course. Your bones are constantly being eaten away, and replaced as part of their maintenance. It's truly amazing, but the secret is definitely, "We can rebuild it" not "Unbreakable".
- andyidsinga 10y agoYes! .. i love thinking about things that way! Speaking about that mentality > the right to repair : https://news.ycombinator.com/item?id=12088631 https://news.ycombinator.com/item?id=12088631 ...raises the question about who can service and repair medical implants. I imagine pace makers would be an interesting case study.
- tunap 10y agoI imagine any inorganic implamt is going to degrade, and have proprietery patents included. Your last question reminded me of the Jarvik Heart, in particular. Interesting read on evolution of the permanent to impermanent artificial heart: http://mobile.nytimes.com/2016/03/21/us/artificial-hearts-ticking-along-decades-after-jarvik-7-debate.html?referer= http://mobile.nytimes.com/2016/03/21/us/artificial-hearts-ti...
- andyidsinga 10y agothat is a great read, thanks!
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- murbard2 10y agoSurely this can't be the firs time someone thinks of making a gold titanium alloy. What did the previous attempts miss?
- the8472 10y agoOther mixes of Au/Ti have been made and used. There is plenty of prior research which the paper also cites. The phase diagram posted in another comment shows that the region in which this particular phase exist is fairly small. Additionally the paper mentions that they had to add a few trace alloying components to stabilize it in that phase. I.e. it takes some effort to get to the point. And even if you can spot a trend by lining up properties of various alloys on the right diagram, investigating that trend may be out of scope for the research you're currently doing.
- taivare 10y agoThis should eventually be cheaper then gold for jewelry and castable an also it might be weldable or at least be able to braze ?
- Mizza 10y agoI bet we'll see this coating golf clubs and tennis rackets (for absolutely no reason) quite soon!
- Coincoin 10y agoNow 30% stronger. Same material as used in aeronautic and surgical field. Military grade!
- jonnathanson 10y agoSelling higher-margin luxury goods to rich people is always a good reason! It really is a fantastic business model.
- zeristor 10y agoHow does one recycle the gold once the patient has deceased? This has just raised what you can afford when you're paying with an arm and a leg.
- zeristor 10y agoThinking about this perhaps the Titanium gold would be a surface layer or coating over Titanium. No doubt there would be metallurgical issues with this. Funnily I had a pre-student job in a coatings company using detonation guns to fire tungsten carbide into metals in order to make them tougher. Could a similar treatment be used for Titanium hip replacements?
- fosco 10y agoReardon metal!