Author Topic: Physicists Combine Gold with Titanium And Quadruple Its Strength  (Read 2922 times)

Offline Space Ghost 1962

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Offline IanThePineapple

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Tell Elon, I think we have some new gridfin materials
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Online Lar

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making gold stronger with titanium is not surprising. Other way round is. The headline has an imprecise referent.. The article is talking about 3:1 Ti:Au (so mostly Ti) alloy that is stronger than pure Ti.

The heat reistance properties are also important, not just strength....
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Offline Nomadd

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 That's not what the article says. The alloy is harder. Not the same thing as stronger.

Offline rpapo

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That's not what the article says. The alloy is harder. Not the same thing as stronger.
In normal metallurgy, harder -> less tough, more brittle.  There is a time and place for harder, and a time and place for tougher.  Brittle is never a good thing.
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Offline Space Ghost 1962

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This material itself may/may not be interesting.

The way the alloy works, as a means to use bonds as like Penrose tiling with valences, is the very interesting part.

Means you can make a variety of new materials with titanium/aluminum/magnesium/nickle. Some with increased tensile strength, some with elastic properties, some less reactive, some with extreme melting point.

These might be desirable for aerospace use.

Online Lar

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That's not what the article says. The alloy is harder. Not the same thing as stronger.

We have a bad thread title then... thanks Nomadd...

Agree with the ghost that if this is a new kind of tiling, it might have far reaching applications...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Tetrakis

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This is not a new tiling, or more precisely a new space group. Furthermore, it is not a "penrose tiling". That term only applies to quasicrystals, which this is not. This is a fairly normal intermetallic compound with some interesting properties, mostly intended for biological implant purposes.  This topic does not belong in "New physics for space technology".

Also its an open access article. When posting to a popular press article about science, its a good idea to post a link to the paper itself.
http://advances.sciencemag.org/content/2/7/e1600319

Offline Space Ghost 1962

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Not like a crystal but more like a glass. Metal alloys have interesting properties that follow amorphous, semiregular patterns like Penrose tiling. So you entirely miss the point.

Which may be why such materials as this have not been found til now. Too rigid and narrow thinking.

Offline Tetrakis

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I did not miss the point. I am a working chemist with experience in inorganic solid state materials.

You are correct that less crystalline materials can be "tougher" and less prone to fracture; this has been known in materials chemistry for decades. But your comment is irrelevant to this paper. They found that the ▀-AuTi3 component of the material is responsible for its high hardness and do not comment on its toughness. Studies of the material surface and bulk composition show that this crystalline material represents the bulk of the compound.

Really this is very well known material science, not new physics. The unexpected hardness is really due to the improved chemical bonding environment in the ▀AuTi3 crystalline phase providing greater than expected improvement. I'll also mention this due to some earlier discussion in the thread: the new material has a much lower melting point than pure titanium despite high hardness.

It really is good work and will certainly be useful, but there is no way that this is "new physics for space technology". More like "New materials for bioimplant technology".

On another note, please familiarize yourself with quasicrystals. They really do mirror "penrose tilings" but are not related to this paper and I think you would find them quite interesting. Unfortuantely, most quasicrystalline materials have worse materials properties than existing substances and have not found much of a niche in applied work.
« Last Edit: 07/09/2017 08:38 PM by Tetrakis »

Online Lar

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(mod)
If someone has a better section to suggest, feel free to PM me or do a report to mod and we'll consider moving the thread. It kinda feels like it fits here more than elsewhere but I agree it's not exactly physics...

And, ghost, don't bite the other forum participants quite so hard, thanks.
« Last Edit: 07/09/2017 08:47 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Space Ghost 1962

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I did not miss the point. I am a working chemist with experience in inorganic solid state materials.

You are correct that less crystalline materials can be "tougher" and less prone to fracture; this has been known in materials chemistry for decades. But your comment is irrelevant to this paper. They found that the ▀-AuTi3 component of the material is responsible for its high hardness and do not comment on its toughness. Studies of the material surface and bulk composition show that this crystalline material represents the bulk of the compound.

The first work with metal enhanced ceramics followed the same pattern. Then they refined processes to allow for more uniform distribution, where the materials had less brittle properties.

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Really this is very well known material science, not new physics. The unexpected hardness is really due to the improved chemical bonding environment in the ▀AuTi3 crystalline phase providing greater than expected improvement.

The new physics part I'm referring to is the nature of the bonds in terms of valence grouping. Which follows other patterns in the peculiarities of titanium alloys.

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I'll also mention this due to some earlier discussion in the thread: the new material has a much lower melting point than pure titanium despite high hardness.

Titanium alloys can be made where depending on the processes used to create them, can have higher/lower melting point, different hardness and durability. Even with similar components.

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It really is good work and will certainly be useful, but there is no way that this is "new physics for space technology". More like "New materials for bioimplant technology".

Where we differ is in the nature of the work. You are looking at it from an "end product", while I notice the ongoing aspect.

Now here's the specific matter for space launch systems - Al-Li alloys have reached limits in how far you can take them. Looking at the mathematical physics for how transitory valence states might allow for enhanced materials out of these existing metals is one way out that is being examined.

Carbon fiber and ways of using metals with it are another, which also has problems, especially with cryogens.

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On another note, please familiarize yourself with quasicrystals. They really do mirror "penrose tilings" but are not related to this paper and I think you would find them quite interesting. Unfortuantely, most quasicrystalline materials have worse materials properties than existing substances and have not found much of a niche in applied work.

Thanks, we agree on them. In fact, its the combination of this with what I'm talking about that may stabilize such.

When I refer to Penrose tiling, am generalizing for a wider audience here a wider case of ordered arrangement, which isn't strictly geometrical, but takes into account bond valance and quantum mechanics (in this case angular momentum of certain filled / unfilled states).

You're welcome to become more specific and assert domain specific terms, but realize that you may step out of one dilemma and into an entirely different one without knowing it.

My interest is in the group theory (mathematics) of the bond structure as a quantum mechanical version of a "ring oscillator". So-called "dynamic stability".

Want more?
[/quote]

Offline Tetrakis

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Single crystals are by definition extremely pure and homogeneous samples. The paper measures the properties of ▀-Ti3Au, a crystalline material, and used microtribology, XRD, and computational tools to probe its properties. By definition, materials measurements of single crystals do not depend on experimental factors like preparation method. Two single crystals of a compound will have identical properties, so long as they share the same crystal structure, regardless of how you got them. 

Hardness is an intrinsic property of covalent crystalline materials, as laid out in reference 23 of the paper under discussion, arising from the net strength of the covalent bonds between atoms in a crystal lattice. From a physical standpoint, a single crystal is an infinitely repeating spacial tiling of a defined unit cell. In the paper, there is a lot of talk about valence electron density. I think you are misunderstanding this term. It is just the total number of valence shell electrons per volume; when considered in combination with the band gap one can estimate the strength of the chemical bonds in a covalent crystal and, with some assumptions and approximation, an estimate of the hardness. This work has nothing to do with defect density, higher-dimensional symmetry as found in quasicrystals, or "transitory valence states" (do you mean transition states?). Also I would say that the new physics you see in "valence grouping" has another name: century old types of chemical bonds, analyzed through a century old technique (x-ray crystallography).

I guess this boils down to the topic of this paper. Its the discovery of a new crystalline material that has high hardness due to efficient chemical bonding. Its not about alloys, blended composites, (both decidedly not new physics) or "transitory valence states/valence grouping".

There is definitely interesting new physics to be found in crystalline materials, for example the root cause of Type II superconductivity. If we knew how that worked we would have room temperature superconductors cracked by now. Unfortunately, that topic is outside the scope of my knowledge (and this paper) and I can't productively engage in a discussion about it. It can be fun to think about sometimes, though.

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My interest is in the group theory (mathematics) of the bond structure as a quantum mechanical version of a "ring oscillator". So-called "dynamic stability".

Can you elaborate on this?
« Last Edit: 07/10/2017 09:39 PM by Tetrakis »

Offline Space Ghost 1962

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Single crystals are by definition extremely pure and homogeneous samples. The paper measures the properties of ▀-Ti3Au, a crystalline material, and used microtribology, XRD, and computational tools to probe its properties. By definition, materials measurements of single crystals do not depend on experimental factors like preparation method. Two single crystals of a compound will have identical properties, so long as they share the same crystal structure, regardless of how you got them.

Actual fabrication processes are more nonuniform. Also, as with inclusion in other materials such as ceramics or glasses, where the quasi-crystalline borders are important to the way the material resists heat flux without mechanical degradation, irregularities become the site of the materials flaws. A practical consideration for aerospace use.

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Hardness is an intrinsic property of covalent crystalline materials, as laid out in reference 23 of the paper under discussion, arising from the net strength of the covalent bonds between atoms in a crystal lattice.
Indeed. It is precisely that where the physics focus comes from here.

The interplay between the covalent and band theory, where specific valence plays a  role.

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From a physical standpoint, a single crystal is an infinitely repeating spacial tiling of a defined unit cell.
Metals can be amorphous, crystalline, or various "hybrids" of both.

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In the paper, there is a lot of talk about valence electron density.
The paper does not speak to the physics of the bond, because the point is to communicate the nature of the material as for application.

The physics of the bond gives the use and nature of the materials as expressed in  "valence electron density".

In the physics of this bond, it is the application of band theory for Group IV metals (and an analogous case in Group III metals).

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I think you are misunderstanding this term. It is just the total number of valence shell electrons per volume; when considered in combination with the band gap one can estimate the strength of the chemical bonds in a covalent crystal and, with some assumptions and approximation, an estimate of the hardness.

My posts are intentionally abbreviated. They do not include definitions. Am using the term "valence" as it applies to band theory.

In this case with band theory it is referring to the specific quantum states of those valence shell electrons, not a total number of a volume. I am not dealing with a chemical situation but a quantum mechanical one.

In fact, it was the characteristics of the possibility of such bonds that allowed the exploration of this material as a material (chemical and materials engineering). The value of this find to condensed matter physicists (and materials engineers) means that they can apply / extend band theory into specific cases of overlapping and partially filled shells with unique angular momentum cases. These can only occur with specific materials. (Physics and chemisty reinforce, and often intertwine, as is the case here. However, they often butt heads over who's view dominates, the internal or the external. As appears to be the case here.)

Titanium has higher stability and lower density(45%) than   steel. Ti(z=22) with a partially filled 3d shell is in the d2s2 configuration and appears in five phases of α(hcp), ω(hexagonal), γ(distorted hcp), δ(distorted bcc) and β(bcc) [1, 2, 3] in which γ and δ are instable phases.

Phases α and ω are  at  room  temperature and atmospheric pressure and phase β is found to be up to 900C  and 8GPa. 

Because of the nature of this work in this paper, calculations show that ω phase is more stable than α phase at 0K. Observed x-ray diffraction have shown that the stability range of α phase varies  between room temperature to around 923K. More on why that matters is below.

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This work has nothing to do with defect density, higher-dimensional symmetry as found in quasicrystals, or "transitory valence states" (do you mean transition states?). Also I would say that the new physics you see in "valence grouping" has another name: century old types of chemical bonds, analyzed through a century old technique (x-ray crystallography).
No it doesn't. And I believe I've spotted the miscommunication - "chemical bonds".

Are you familiar with peculiarities of how high temperature coatings and alloys like mondaloy? That you can operate in extreme environments with them?

Are you also familiar with AMO work, and that with related semiconductor "chillers", that allow cancellation of thermal energy to achieve the localized effect of lower thermal lattice energies for constrained function?

The "new physics" aspects in condensed matter research focuses on using the above mentioned phases to achieve similar effects in materials like Ti, Al, and Mg.

Now we enter the proprietary area I won't descend further. The "hardness" evidenced by the above bonds in this material (and similar ones) can be used to absorb the lattice energies allowing such desirable materials.

So band theory is selectively extended to allow translation of angular momentum quantum states of mostly d orbital valences, only possible on certain covalent bond structures with metals with bands that work with slightly irregular (almost like a semiconductor) arrangement. The above mentioned phases of Ti occur as states to alternate through.

That is the point. Sorry if its not you "centuries old" use of chemical bond types. It's a necessary hybrid.

And its not pure chemistry, just like the other materials I've alluded to.

Sorry, am just a simple mathematician helping those awful condensed matter physicists to once again wreck the pristine, centuries old chemistry of common metals. Apologize for crossing disciplines again in pursuit of solving yet another applied math problem.

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My interest is in the group theory (mathematics) of the bond structure as a quantum mechanical version of a "ring oscillator". So-called "dynamic stability".

Can you elaborate on this?
Sure.

In group theory we have the concept of a "ring" - a cyclic state structure that repeats in successive order. In electronics, we can use this to make an oscillator that likewise sequences in a pattern that can be used to impart a phased arrangement of discrete energy packets (overtones in electronic music synthesizers, where they mimic certain musical instruments/bells).

You can do the same in condensed matter to evoke properties of the materials. The benefit is to stochastically exceed the static durability of a substance.

Offline sanman

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Tell T̶o̶n̶y̶ ̶S̶t̶a̶r̶k̶Elon to make his next (space)suit out of this stuff - it has a nice aesthetic look

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