Questions tagged [metals]
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Voids in steel?
I have found black areas in the the surface of some steel. Are these voids from the original manufacure or are they created by corrosion?
This one is approx 1mm x 0.5mm.
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1answer
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Help with deriving simple heat equation [closed]
$$j^{q}=\frac{1}{2} n v[\varepsilon(T[x-v \tau])-\varepsilon(T[x+v \tau])]$$
To this:
$$j^{q}=n v^{2} \tau \frac{d \varepsilon}{d T}\left(-\frac{d T}{d x}\right)$$
At first I was thinking of using ...
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0answers
24 views
Drude model electronic drift momentum rigorously derived
Specifically I'm referring to the equation below which I took from wikipedia.
The derivation of this equation based on the Drude model seems to somewhat standard as all the resources I've looked at ...
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1answer
31 views
Why are experimentally obtained specific heat values for different metals higher than the theoretical values?
I have just performed an experimental measurement of the specific heat of various metals by introducing an electrically heated probe and measuring mass and temperature difference with respect to the ...
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1answer
57 views
What are physical obstacles for rare earth metal synthesis in nuclear reactors in industrial scale? [closed]
Diminishing availability of rare earth metals prohibits expansion of traditional and quantum computing and low temperature technologies. So - my question is about artificial synthesis of rare earth ...
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1answer
24 views
How to determine whether an alloy is single or multi phase
I would like to know what methods would be suitable to determine if an alloy of 2 elements is a single phase or two phase alloy.
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11answers
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Are there physical properties that can be used to differentiate stainless steel from copper in a home environment? [closed]
So the backstory is that I purchased a reusable drinking straw that is copper coloured, but is advertised to be stainless steel. That got me thinking about whether I could be sure it was one or the ...
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0answers
40 views
What is the difference between metallicity and semimetallicity?
I am looking for a definition of semimetallicity from an experimental point of view ( $\rho(T)$, carrier density, mean free path, scattering time, etc.) and from a theoretical point of view. Can ...
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0answers
37 views
InterAtomic Distance between atoms of a molten metal
I was figuring out and researching on interatomic/internuclear distance of metals (particularly Aluminium), but then I started wondering on the difference between magnitudes of interatomic distances ...
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0answers
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Vertical vs. lateral malleability of copper plate in fine art etching [closed]
The malleability of copper has, in part, contributed to the viability of copper plate etching in fine art through the ages, by offering the ability to “erase” or flatten inadvertently placed or too ...
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1answer
38 views
Is rust a good thermal insulator as opposed to bare steel or hardened clay?
I have no idea if this is the correct site to find an answer on this topic but considering it's a question of physical interactions I wanna give it a shot. I am in no way a physicist, just a hobbyist ...
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0answers
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Inverse work function?
The work function is the "work necessary to get the electron out of the metal" [Millikan] and plays an important role in the photoelectric effect.
I assume that the "work gained by absorbing an ...
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1answer
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Polarization density inside perfect conductor placed in an external electric field
I've stumbled about the following problem that I do not understand:
The polarization density P is defined such that its divergence gives the charge density due to bound (immobile) charges in a ...
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1answer
31 views
Does “charge density” account for all charges, or only negative charges, and do opposite charges cancel each other or add?
if I had 10 electrons and 8 protons in a meter cubed would the charge density be 2 or 10 or 18? I suspect 10, but I don't see why charge density only takes into account the negative charges.
another ...
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2answers
59 views
How is the a Fermi surface different from a Fermi sphere?
How is a Fermi surface (a surface in reciprocal space separating the occupied electron states from unoccupied states at $T=0$) different from a Fermi sphere? Is Fermi sphere a special case of Fermi ...
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1answer
37 views
Carbide machining inserts are supposedly extremely brittle but they don't break when machining why?
So everywhere I read I hear that carbide inserts for metal machining are extremely brittle and they will break very easily if you say drop them. However, you put them in your tool holder and spin up ...
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1answer
37 views
What is the term for the light-sensitive metals in the photoelectric effect?
Can anyone please tell me the term used to refer to metals such as those used in photoelectric effect which can generate a current from light?
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3answers
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Ray sun heating
I recently got a curious question about the sun rays. Is there a material that can absorbs most of them and turn it into pure heat?
For example, we all know that dark material (black t-shirts) get ...
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2answers
114 views
Star Trek - Transparent Metals Possible?
Is the concept of transparent metals (like the transparent aluminum in Star Trek IV - Voyage Home) a real-life concept? Or is it far-fetched movie fiction?
Thus my main question then is: could we ...
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0answers
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Can any element be a metal?
I was reading that hydrogen can become a metal in some cases, like in Jupiter, and the same for helium. Is this true for all non-metals?
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1answer
51 views
Why is the residual-resistance ratio (RRR) a measure of good crystalline quality?
I am currently revising a paper on a few parameters of metallic Al, and it indicates that a higher RRR is a measure of good crystalline quality. My question is why would this be the case, if having a ...
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1answer
37 views
Where is the data for work functions of simple metals?
I am looking for actual, published data on the work function of metals (Al, Au, Cu) that I can analyze by myself using Matlab. Google Scholar only offers published articles on the utilization of the ...
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0answers
143 views
Reason for gold being the most malleable and ductile of metals
I understand how fcc structure enables plastic deformation in metals, but why is gold, in particular, the most malleable and ductile of fcc metals? Is there something about the electronic structure ...
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1answer
65 views
Can I trap mosquitos with Coulomb's force? [closed]
Can I fill a metallic conductor with a very large positive charge, attach it with a insulator to a wall, put it near a window under the sun (visible light and UV in order to cause it to expell ...
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3answers
176 views
Why do metals have high optical reflectivity?
What's the reason behind metals' high optical reflectivity?
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0answers
32 views
Why does nickel permeability decreases past 250 KHz?
I found this graph of nickel magnetic permeability vs frequency,it start to drop at around 250 KHz.Why isnt the permeability constant at all frequencies?
Can that frequency curve somehow be ...
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0answers
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Why do both these molten metals round in a crucible?
In one of my classes this past semester, we did a casting lab. In this lab we used an induction furnace which uses a coil to generate heat within the material. One of the things that I noticed, was ...
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1answer
263 views
Even/odd number of electrons per primitive cell and conductivity
In this pdf it says
Because the number of electron states in a Brillouin zone is twice the number of primitive cells in a Bravais lattice (the factor two comes from spin), the zone can be ...
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1answer
60 views
Why are powdered silver and powdered platinum black?
The quantum-mechanical (relativistic) explanations for the observed colours of copper, silver & gold don't appear to explain the black colours of powdered silver (& powdered platinum). Can ...
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1answer
64 views
Why do thermal hotspots in a metallic nanoparticle do not match it's optical hotspots?
I am a little bit confused here. When a metallic nanoparticle is impinged with light at its resonance, the electric field is greatly enhanced at the surface along the polarisation of the wave(suppose ...
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2answers
69 views
What is the significance of the time $\hbar/E_F$ where $E_F$ is the Fermi energy?
For free electrons in a metal, the Fermi energy $E_F$ (defined as the highest filled energy level at $T=0$). It represents a characteristic energy scale of the system as well as the energy of the ...
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2answers
95 views
Why the electric field inside a metal sphere carrying a charge Q is zero?
I was solving some problem regarding the polarization during this I came across an example 4.5 in Griffith's where it is written that the Electric field inside the metal sphere carrying a charge Q is ...
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0answers
36 views
Equation of state for liquid metals (CFD Application)
I am currently looking for the Equation of state used for metals (fluid state) for CFD Application on metallurgy.
Do you know a book where I can find them?
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1answer
55 views
Does corrosion of metals depend on electron degeneracy pressure?
Corrosion is about losing electrons for the corroded metal and gaining electrons for the oxidising substance.
Is it correct to assume that what controls this process is the electron degeneracy ...
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0answers
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raman tensor of graphène and its polarisability
I want ask about the raman tensor of graphene
all that I know, the raman spectrum of graphene has 2 main peak G and 2D.
but what about its tensor raman.
I know that the metals materials don't have ...
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2answers
215 views
Is there a way to make infrared pass through metals?
I am curious to know a way that will make infrared pass through metals. Metals are good reflectors of infrared,can we manipulate the wave in order to make them pass through metals?.
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1answer
44 views
How do liquid metals work?
So in solid metals they atoms give off electrons, which are delocalised and hold together all the metal atoms. But that's not the case in liquid metals, right? What holds together the individual atoms ...
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2answers
776 views
What is the source for Osmium's colour?
The majority of metals are known for appearing grey to our eyes, cf. e.g. Why are most metals gray/silver? But the main exceptions to this are the "famous" group eleven metals, where their distinctive ...
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1answer
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How do electrons in a conductor physically respond to radio waves?
If a radio wave hits a thick piece of metal, it's my understanding that the metal will for the most part reflect the wave. What I'm unclear about is how the electrons flow in a metal that's being ...
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1answer
1k views
Can you make a metal denser by melting it and make it cool down under high pressure?
The answer is probably no. But can you make a metal denser by melting it and make it cool down under high pressure? Or would it just crack under internal stress when it returns to a solid? I'm going ...
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1answer
252 views
Is metal electrical conductivity correlated with optical reflectivity?
Silver is metal with highest electrical conductivity.I read that it have highest optical reflectivity,that it shines most from all metals.
Is there link between conductivity and how shiny the metal ...
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1answer
414 views
What is the complex conductivity of a metal?
I was told that it is possible to describe frequency dependent properties of metals in terms of the equations of motions of the charge carriers. In order to do so the Drude model can be exploited and ...
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0answers
146 views
Is it true that metallic rod serves as a shortcut for the electric field?
Let's suppose that we placed a charge nearby one of the end of the long metallic rod (the length of the rod is $L$). Without rod, an electric field will decrease as an inverse square of the distance ...
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0answers
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What's the transition from “metal” to “electron-degenerate matter” look like?
Question: Say that we had metallic water and compressed it until it qualitatively resembled the state of matter in a white dwarf: what would that transition look like?
Background (revised to be ...
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0answers
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Why spin-orbit coupling difference is smaller in TiO2 than Ti metal?
Why spin-orbit coupling difference is smaller in TiO2 than Ti metal?
Like in the figure
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0answers
26 views
Liquid galium speed of sound
What is speed of sound in liquid galium? I see water have speed 1400 m/s,and ice 4000 m/s so the change is very big in solid/liquid phase change,I assume same is true for pure metal like galium.There ...
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3answers
87 views
Gold forensics - can gold's source mine be determined? [closed]
A lot of gold was moved from it source in the west to Europe and other world powers in the 16th and following centuries and I was curious if such gold artifacts could be tied to their source or not.
...
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1answer
51 views
How to see s, p, d, and other band in the band diagram? Is it possible?
I am reading this book, to understand magnetism in material.
It is stated there that the d-bands overlap the next higher s-band.
I am aware about Hund's rule.
How to see that in the band diagram? ...
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1answer
132 views
What is the name of metal-metal junction?
When two different metals come in contact, a junction at their contact is created.
What is the name of that junction?
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29 views
Growth of iron crystals
What determines how large a crystal of iron will grow when heat and pressure are applied?
I was thinking about the Earth's core. Some have postulated that a large iron crystal is at the center of the ...
