Researchers from North Carolina State University and Qatar University have developed a new "high-entropy" metal alloy that has a higher strength-to-weight ratio than any other existing metal material...."The density is comparable to aluminum, but it is stronger than titanium alloys," says Dr. Carl Koch, Kobe Steel Distinguished Professor of Materials Science and Engineering at NC State and senior author of a paper on the work."It has a combination of high strength and low density that is, as far as we can tell, unmatched by any other metallic material. The strength-to-weight ratio is comparable to some ceramics, but we think it's tougher - less brittle - than ceramics."
Here's a report about the development of a new alloy which is supposedly as light as aluminum and at least as strong than titanium:http://www.spacedaily.com/reports/New_high_entropy_alloy_light_as_aluminum_as_strong_as_titanium_999.htmlHere's also an interesting article from The Economist talking about a new iron-aluminum-nickel alloy that is claimed to have comparable strength to titanium, but at a tenth the cost:http://www.economist.com/news/science-and-technology/21642107-alloy-iron-and-aluminium-good-titanium-tenthHow much scope is there for further improvements in alloy properties, and what are the best candidates?
Hanelyp has it right. There are other factors to consider. The primary property is strength to weight, but other properties can make our break its utility for a given application. Aluminum lithium alloys work well because they combine good strength to weight, good toughness, and are relatively easy to process (weldable, machinable, etc.)Titanium based alloys all suffer from being difficult/expensive to process. They absorb oxygen at elevated temps, and become brittle. The two you linked both seem to be sacrificing ductility for tensile strength, but there probably is some net benefit. If they have a fatigue limit, they could have one advantage over aluminum alloys.The cool thing about metallurgy is that an addition of just a few percent or a different heat treat can greatly change the properties of an alloy and fix a shortcoming. When there is a large financial incentive, more materials research is done, and they hone in on some ideal alloys (see nickel superalloys as an example).
BTW, an important property that aerospace designers optimize for is elastic modulus, i.e. stiffness. It is, however, inversely proportional to resilience (given the same strength) from a mathematical point of view. In other words, stiffer structures are more brittle. Personally, I think stiffness is over-rated (toughness is likewise under-rated), at least in aerospace, since it leads to operational and fabrication complexities. But of course, this strongly depends on your application.
Quote from: Robotbeat on 02/07/2015 04:19 pmBTW, an important property that aerospace designers optimize for is elastic modulus, i.e. stiffness. It is, however, inversely proportional to resilience (given the same strength) from a mathematical point of view. In other words, stiffer structures are more brittle. Personally, I think stiffness is over-rated (toughness is likewise under-rated), at least in aerospace, since it leads to operational and fabrication complexities. But of course, this strongly depends on your application.No, stiffness and resilience are only loosely related.Stiffness is the reaction of material to external forces, resilience is the capacity of material to absorb and dissipate great amount of energy before breakingThe complementary (inverse) of stiffness is flexibility
Unfortunately you are still wrong.The formula you show is valid only for the linear part of the stress-strain curve; from the Wikipedia article:The modulus of resilience is defined as the maximum energy that can be absorbed per unit volume without creating a permanent distortion. It can be calculated by integrating the stress-strain curve from zero to the elastic limit.Integrating the linear part you get that formula.But true resilient material can be recognized by the elastoplastic stress-strain curve (slope then a constant stress deformation) and here the formula has no validity.
I stress, stiffness and resilience are only loosely related.
Quote from: cambrianera on 02/07/2015 06:08 pmUnfortunately you are still wrong.The formula you show is valid only for the linear part of the stress-strain curve; from the Wikipedia article:The modulus of resilience is defined as the maximum energy that can be absorbed per unit volume without creating a permanent distortion. It can be calculated by integrating the stress-strain curve from zero to the elastic limit.Integrating the linear part you get that formula.But true resilient material can be recognized by the elastoplastic stress-strain curve (slope then a constant stress deformation) and here the formula has no validity.Nope! That's toughness, not resilience. Either use the industry standard, textbook definitions or don't go correcting people who do. By standard definitions, I'm clearly right and you're clearly wrong (in your contradiction). No shame in that, by the way.QuoteI stress, stiffness and resilience are only loosely related.Except they aren't "loosely related." Elastic modulus (i.e. stiffness) and resilience are inversely proportional, as any material science textbook would show you. There's no "loosely" in there, it flows directly from the definitions. Good pun, by the way!
A company called Modumetal has come out with a new nano-laminated metal process which apparently increases strength tenfold and can also be used to increase corrosion resistance:http://www.technologyreview.com/news/534796/nano-manufacturing-makes-steel-10-times-stronger/Hmm, I wonder if this process is compatible with 3D printing? Maybe the increased corrosion resistance could be useful for an RD-180 style of closed-cycle engine.
I thought electroforming is already the method of choice for fabricating regenerative cooling channels.
The reason why I mentioned 3D printing, is because this technique of varying the voltage as you go could then be used to manipulate the material properties on the small scale, across the printing process.
There has already been research into electroforming as a 3d printing technique, using lasers to thermally catalyze where the deposition occurs.
it may not be the strongest but this is cool stuff:http://phys.org/news/2015-05-metal-composite-literally-boat.html
The cool thing about metallurgy is that an addition of just a few percent or a different heat treat can greatly change the properties of an alloy and fix a shortcoming.
If heat treatment is important, how is that affected when materials are welded?
I'm thinking if there are remnants of neutron stars in your back yard, you iz a lucky ducky!http://www.sciencedaily.com/releases/2009/05/090506110202.htm
Squeezed together by gravitational force, the crust can withstand a breaking strain 10 billion times the pressure it would take to snap steel.
The only things more dense are black holes, as a teaspoonful of neutron star matter would weigh about 100 million tons.
High strength is what is sought after, not just absolute strength.
There are some next to fantasy prospects that could be possible in the future: Atoms made with substitutes for the regular protons and neutrons and even electrons. Because these would be tiny compared to normal atoms (as much as 2000 times smaller) the bonding strength would be exponentially greater than the electronic and nuclear bonding strength of regular matter.
Referring to my previous post; what would be the density of stuff made out of these brave new mini-atoms?
The smallest magatoms have diameters of 3E-19 m, 300 million times smaller than an atom of conventional matter. As a typical magatom is 10,000 times heavier than a typical conventional atom, magmatter’s typical density is 1E33 kg/m3. Since force is energy per unit distance, the force needed to break a magchemical bond is larger than that needed to break an electronic chemical bond by a factor of the energy scaling (300 GeV / 13.7 eV) divided by the length scaling, or 7 million trillion (7E18). The strength of a material is usually defined as the force per unit area required to make the material fail. Since each magchemical bond can withstand 7E18 times greater force, and there are (300 million)2 times more bonds per unit area, the strength of magmatter is about 8E35 times greater than that of its normal matter equivalent.
Quote from: R7 on 05/16/2015 08:29 amHigh strength is what is sought after, not just absolute strength.Excellent point.This is a very important factor for flight. It's why Magnesium (poor absolute strength) is good (and was used on some early US rocket stages, usually with storable propellants). The lightness counteracts the weakness. As always in design it was good enough to get the job done, which is what counts. But it's ability to burn quite well has always made rocket engineers nervous. Interestingly in similar test Aluminum does not work out much better in LOX, the re forming oxide layer seems to keep people happy to use it.BTW on welding heat treated alloys we probably should mention diffusion bonding, another non melting process. Works great with Titanium, as the oxide dissolves in the metal. Sadly that does not work with Aluminum, although Aluminum DB does seem to have been extensively researched I can't find anyone who uses it. Car radiators seem to use vacuum brazing with an intermediate layer instead.
I would also guess that monopole matter would have no unstable elements or isotopes in it's periodic table. E.G; elements above Monopole Bismuth would be completely stable. Monopole matter decay uses a different process than w bosons or meson mediated decay. I think it would be mediated by certain species of monopole or by mono-antiparticle annihilation.
But has anyone seen a monopole in the wild yet?
Quote from: Stormbringer on 05/17/2015 10:56 pmI would also guess that monopole matter would have no unstable elements or isotopes in it's periodic table. E.G; elements above Monopole Bismuth would be completely stable. Monopole matter decay uses a different process than w bosons or meson mediated decay. I think it would be mediated by certain species of monopole or by mono-antiparticle annihilation.But has anyone seen a monopole in the wild yet?
monopoles are real? or is this just another example of emergent monopole like behavior?https://phys.org/news/2018-06-quantum-gas-reveals-path-bending-monopole.htmlIf it is yet another emergent monopole the cosmos is getting crowded with them... This would be like the third one I have read about that appears under different circumstances than the first two examples.