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1answer
2k views

What makes some aluminium alloys so strong while remaining light?

Compared to cast iron, for example, certain alloys of aluminum have both strength and weight advantages. How can aluminum be so strong while being so light?
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2answers
39 views

How to attract liquid metal with magnets

I would like to know if there is any way that I could make mercury or another liquid metal be attracted or repelled by magnets. Absolutely any solution would be okay with me. For example... can I ...
4
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2answers
274 views

Is there any relation between temperature dependence of resistance and fermi energy in metals?

Given that the resistance varies linearly with temperature in metals, is there any way we can calculate the Fermi energy from this information?
0
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0answers
23 views

absorption spectrum of aluminum

I am trying to find the absorption spectrum of aluminum but only can find reflectivity of it and other optical properties. It is easy to find absorption of aluminum oxide, foams etc. but not possible ...
10
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1answer
206 views

Third-order susceptibilities of metals?

Can anyone point me to a source for measurements of the third-order nonlinear electric susceptibilities $\chi^{(3)}$ of various metals? Specifically in relation to the AC Kerr effect, so measurements ...
0
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1answer
310 views

Malleability in metals

I am trying to understand malleability in metal as a result of the micro structure. I am focusing on the metals of antiquity (in order of decreased malleability): Gold, Silver, Copper, and Iron. While ...
0
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0answers
33 views

Model of the nucleus as fermi gas

I am taking an introductory course in modern physics, and am reviewing some of the exams from previous years. In our course, we studies the Fermi gas model for electrons in a metal. In one of the ...
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0answers
45 views

Can a magnetic field weaken aluminum?

I'm wondering if there is any reason to suspect that applying a magnetic field to a piece of solid aluminum would weaken it structurally in any way. The application is that I would like to put a stir ...
2
votes
2answers
207 views

Is this a correct description of bonding in a metal?

I am reading the paper "Twenty five years of Finnis-Sinclair potentials" by Graeme Ackland, Adrian Sutton, and Vasek Vitek, Philosophical Magazine 2009, 89, 3111-3116. It is a review-type article ...
3
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1answer
122 views

Do Shape Memory Alloys (SMA) work harden?

We had a piece of this thin Shape Memory Alloy in class, (I think it was called nitinol, but I think thats a brand name) the teacher showed how it is very flexible and springy, and will return to it's ...
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1answer
14k views

Dielectric constant or permittivity of metals

I'm wondering what the dielectric constant or permittivity of metals is --particularly copper. Do metals have an infinite permittivity?
3
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1answer
65 views

What happens to the electron density in a metal during an electric discharge?

Suppose we are able to see into a grain of metal at the boundary between the grain and air (perhaps along one of the faces of this cube): (Source: Wikimedia Commons.) This image does not show the ...
14
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2answers
576 views

Why would different metals glow red at different temperatures?

According to everything I've been taught about incandescence and black-body radiation, and some quick Googling to confirm I'm not crazy, just about everything, regardless of composition, should start ...
2
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0answers
162 views

Could a falling office tower cause the melting of its iron or steel support structure? [closed]

Discussion on META: Questions related to geopolitical events Suppose you have an office tower, weighing around 300,000 metric tons, and has a height of ...
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4answers
4k views

How does positive charge spread out in conductors?

I know that when there are excess positive charges in a conductor, for example, a metal sphere, the positive charges will spread out over its surface. However, I am confused about how this excess ...
2
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0answers
61 views

What is “Accumulated plastic strain rate” in Current yield Norton law?

I'm doing FEA of steel under high strain rates and using Elasto-ViscoPlastic material model, with Von-mises yield criterion along with Isotropic hardening. The strain rate sensitivity is addressed by ...
0
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0answers
10 views

Are magnets attracted to mu-metal?

Are magnets attracted to mu-metal? Be aware that when watching videos of mu-metal they may have metals that are attached to the mu-metal and are attacted to magnets. Please don't get them confused.
0
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1answer
46 views

Can a magnetic ball “diffract” around a metal object?

Consider a magnetic ball falling through a copper pipe. It falls slower than it would if it wasn't near any copper. We can use this to determine that the closer a magnetic ball is to copper, the ...
2
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0answers
35 views

What kind of cheap, available, magnetic metal could I use for my boardgame? [closed]

My question revolves around my need to snap plaster walls to plaster dungeon floors for a boardgame called Dungeons & Dragons. My intention is to glue and paint over metallic strips under the ...
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0answers
11 views

Is it posssible to numerically simulate a metal layer the same way as a semiconductor one

I need to simulate a schottky junction device. Unfortunately, the software for simulation (AFORS-HET) doesn't allow adding metal (I need to simulate aluminum contact) layers (but it allows to add ...
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4answers
345 views

Measuring electric conductivity

My daughter is doing a science experiment on which metal (e.g., copper, silver, aluminum, iron) has maximum electric conductivity. We are assuming we can accomplish this by using different metal, 3 to ...
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6answers
16k views

Why are most metals gray/silver?

Why do most metals (iron, tin, aluminum, lead, zinc, tungsten, nickel, etc.) appear silver or gray in color? (What atomic characteristics determine the color?) What makes copper and gold have ...
0
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2answers
33 views

Enhancing of EM waves through a materal or waveguide

I'm wondering whether there are materials for which an incident EM wave would behave as $\vec E(z,t)=\vec E_0 e^{\kappa z}e^{i(kz-\omega t)}$ where z describes how far from the surface the fields are ...
0
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1answer
10 views

Passive cathodic protection

Trying to understand what is happening when we need protect peace of Fe by placing on it more active metal (for example Zn) like ...
2
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2answers
75 views

Why doesn't dielectric materials have coloured reflections like conductors?

I'm a 3D artist trying to learn the basic (or perhaps even intermediate) level of physics of photorealistic rendering. But most artist and tutorials on the internet have little to no clue of the ...
0
votes
1answer
41 views

crystal structure of metals

I am studying solid state physics and I'm a complete newbie in that sense. I know that semiconductors and group IV elements bond themselves in the FCC structure with covalent bonds which satiate the ...
2
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2answers
78 views

Do metals *really* conduct at zero temperature?

The questions is mostly in the title, but might expose another of my misunderstanding of the band structure of solids and how that leads to metals and insulators. If we have a solid, and the fermi ...
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2answers
263 views

Can metal rods detect underground wires?

Until not long ago, I was working in the drilling and infrastructure business. Some people I was working with used metal rods as a "quick and dirty" method of detecting underground wiring, before ...
0
votes
1answer
116 views

How quickly does a small piece of molten steel cool at room temperatures?

Say I have a $(\frac{1}{2}D)^2 \pi \times \ell = (.05)^2 \pi \times .03 \approx 0.000236 \ \text{mm}^3$ piece of molten steel freshly spewed out of a hot nozzle. Now assuming the nozzle moves away ...
3
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2answers
22k views

Why is stainless steel a poor conductor of electricity?

I recently had a metal plate put in my shoulder and was wondering why stainless steel isn't a good conductor (At least I hope it isn't). Does the alloy just lack free electrons? Why is that?
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0answers
31 views

Why can we treat (most) metals classically at room temperature?

When we consider how light and metals interact with each other at room temperature, the Drude model, which is a classical theory, is usually and successfully used. My lecturer explained something ...
0
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2answers
65 views

What is a simple calculation to figure out how many watts needed to maintain a hot piece of tungsten?

The specific heat of tungsten is $.13 (\text{kJ /(kg K)})$. 1 cubic cm of tungsten is .0193 kg And the melting point of stainless steel is $1900 \deg \text{K}$ conservatively (giving it plenty of ...
2
votes
1answer
65 views

What determines the rate of vibration decay of a metal?

Suppose we have a tuning fork in a vacuum and strike it. Is there anything in the theory of metals that would predict that the tuning fork's vibration amplitude would decrease with time. Put another ...
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vote
3answers
61 views

How to measure thickness of an ultra-thin metal layer?

I have a sample of a metal (aluminum/oxide) layer with a gradual thickness ranging from monolayer to 100nm. This layer is deposited on a transparent substrate, like glass. How can I measure this ...
0
votes
1answer
26 views

Does a crucible need to be fired in a kiln before use?

Say I made a crucible out of aluminum oxide primarily. Won't it be fired by normal use of it or do you have to pre-fire it? I understand they do that to get a consistent mass measurement. But does ...
2
votes
1answer
103 views

Why is communication lost in lifts?

Why is communication lost in lifts and cellars? For example, If I want to phone to someone, there is no signal communication in lift. Who may explain it?
2
votes
1answer
67 views

Why titanium “writes” on glass , meanwhile don't scratching it?

It is possible to "write" on a piece of glass with a bar of titanium without scratching the glass. I think the explanation is that molecular connections in glass are stronger than in titanium and ...
0
votes
1answer
46 views

Effect of frequency on magnitude of photo current

In a photoelectric experiment, if the frequency of incident light is slightly raised while holding intensity constant, I understand that the number of incident photons decreases. This in turn results ...
2
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1answer
129 views

How can metals absorb light?

We're told that semiconductors have a bandgap and photons of an energy greater than the bandgap can be absorbed, exciting electrons from the valence band to conduction band. This therefore defines ...
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2answers
82 views

Does hardening reduce the ductility of a metal?

Is hardening equivalent with reducing the ductility of a metal and improving the yield strength of it?
0
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1answer
84 views

What makes metal change its color during heating?

What happens on atomic and molecular level? Is this true also for non-metals and metalloids?
0
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3answers
77 views

How can electrons still occupy orbitals in metals if they are delocalised?

I was reading about why most metals are gray/silvery in colour and it said something about d orbital electrons transitioning to s orbitals and the visible spectrum not having sufficient energy to ...
44
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2answers
6k views

Why are gold mirrors yellow?

Why are golden mirrors yellow? Do they add a yellow component to the spectrum or absorb non-yellow components? If they absorb, then why are they used in telescopes being imperfect? If they add a ...
5
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3answers
500 views

Why do magnets silence anvils?

Today I've been to a forge. The blacksmith demonstrated that if he beats the anvil without a magnet attached, it make horrible noises. As soon as he reattached it, the sound of the anvil was way more ...
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0answers
83 views

Exact expression for the coefficient in Bloch-Grüneisen (BG) formula?

In most representations of the BG formula, there is a coefficient (usually left vague as an experimental parameter, but sometimes written out "analytically") in front of the integral: $$\rho=\rho_0 +A ...
4
votes
2answers
214 views

What is the most efficient way to use a blow torch?

Let's start with a torch and a piece of titanium. What is the fastest way to get the titanium up to red hot? Whenever I ask my science-y friends they like to point out that the bright blue tip is ...
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0answers
197 views

Why don't HCP metals have a brittle-to-ductile temperature transition?

I thought it had to do with the amount of slip systems...because BCC doesn't have as many slip planes, it cracks at low temperatures, while FCC has enough slip planes that it is not dependent upon ...
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0answers
27 views

Why do we use the Einstein Solid for the heat capacity of metals at high T?

I am not sure how to best formulate this question, but see the title? What physical reason (or what equation can I look at) to see that, at high temperatures, all the electrons will oscillate with the ...
0
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0answers
18 views

Wave propagation in 2D metal cavity

I would like to know there is an analytic solution for the propagation of electromagnetic waves in metals in a 2D case. The 1D case is well known to lead to a traveling wave with exponential decay ...
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3answers
486 views

Is there any material that is NOT conductive and IS magnetically attractive?

Is there any material which is NOT conductive and IS magnetically attractive? I am in need of a material which I can shape and use within a machine. It must be very attracted to magnets similarly to ...