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3
votes
1answer
108 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 ...
1
vote
0answers
15 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 ...
2
votes
1answer
175 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 ...
0
votes
0answers
13 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
votes
0answers
10 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 ...
4
votes
1answer
76 views

What is the fastest way to heat up a piece of metal at home?

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 ...
8
votes
1answer
161 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 ...
1
vote
3answers
146 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 ...
-2
votes
0answers
31 views

Conduction band in solid material

In an any solid material like metal or nonmetal, the atoms are closely placed. There are two important band in metals and nonmetals called the conduction band, and the valence band. We know that ...
2
votes
2answers
98 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
votes
1answer
43 views

When metal solidified, why is its surface not flat like polished?

I expect that what one can see on the outside of a just solidified piece of metal is just the "raw" surface of the inner stucture. Solidifying metals or alloys arranges in partial christal latices ...
6
votes
3answers
24k views

In electrostatics, why the electric field inside a conductor is zero?

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero. I ...
0
votes
1answer
182 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 ...
4
votes
1answer
376 views

Impurity scattering temperature dependence

Is there any temperature dependence of relaxation time in impurity scattering of conducting electrons? It seems to me that there is none. But, some people claim that there is. So if you could ...
3
votes
1answer
32 views

Reflection, Transmission, and Plasma Frequency

Does anyone have a good, clear explanation of why and how this works? I don't understand the following. Say you have a piece of metal with a plasma frequency $\omega_p$. This is like a resonant ...
0
votes
1answer
28 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
votes
0answers
15 views

What is an isostatic gas?

I'm learning about Hot Isostatic Pressing (HIP), but I don't understand what an isostatic gas is. Can someone help me?
1
vote
1answer
71 views

Can lightning actually weld fillings in your teeth?

So, I remember sometime in my childhood, someone was teaching me about lightning safety, and they explained that it was important to crouch low but keep as little contact with the ground as possible, ...
0
votes
0answers
11 views

Does wetting of fabric surfaces depend on the microscopic surface structure?

I am trying to coat a polymer fabric with a metal alloy by dipping it into the molten metal. (For example a polyamide like Nylon in eutectic Bi/Sn alloy at 138°C , as in Wetting the surface for ...
0
votes
0answers
36 views

Wetting the surface for soaking Nylon fabric in metal

I'm trying to create metal covered lace. My sister would use it as an artistic material. An interesting material A relevant point is that the mechanical rigidity of the metal is used, so it is not ...
2
votes
1answer
56 views

How is spring steel so hard?

The mechanical properties of a steel object are influenced by the metal composition, the manufacturing process, and the final heat treatment of the object. Spring steel is a steel that was heat ...
2
votes
1answer
65 views

The outside of a steel teapot is hot to touch. Does this mean that the water inside is necessarily at least as hot?

Some teapots, like this one Are made from thin steel which conducts the heat of the teapot quite well, meaning that you can't comfortable hold the sides while they're full of hot water. Tonight I ...
5
votes
3answers
633 views

How hot can metal get in sunlight? [closed]

I will make some 5mm blackened steel letters for a building. Now, in the sunlight in summer, how hot can they get? EDIT: i want to place some LEDs on the back of the letters. now the question is if ...
0
votes
2answers
34 views

Does the Photoelectric Effect cause any kind of decay?

From my understanding, the Photoelectric Effect knocks electrons off of some metal using photons. Since electrons are being thrown out of the metal, does this cause some kind of decay?
1
vote
1answer
77 views

What actually happens when electrons 'collide' with other electrons in a conductor to produce heat in an electrical circuit?

Textbooks describe resistance as involving electrons colliding with other ions in metals, resulting in a heating effect, though how exactly is this achieved? Although I am not required to learn the ...
51
votes
6answers
11k 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 ...
4
votes
1answer
38 views

Temperature effects on lead against radiation

I would like to know if bringing lead to near absolute zero temperatures would have any affects on how resistive it is against gamma radiation. It takes 40 centimeters of lead to reduce gamma ...
9
votes
3answers
273 views

Why are permanent magnets permanent?

Let me see if I get it right. When an iron bar is attracted by a permanent magnet it becomes a magnet itself because all of its magnetic domains start to point in the same direction. When the iron bar ...
2
votes
1answer
108 views

Cold welding of a metallic surface

I have heard of cold welding, it's said that it's only possible if the surface is very clean. Can cold welding be accomplished by shearing a metal object and then immediately touching the newly ...
0
votes
1answer
39 views

Electrical conductivity of metals on heating

What effect does heating have on metals (to be specific, on the electrical conductivity) ? And why does it have that effect?
2
votes
3answers
353 views

How does the number of electrons and protons determine the melting point and hardness of a solid?

How does the number of electrons, neutrons and protons determine the melting point and hardness of a solid/metal? And is it possible to create custom elements which is very strong and have very high ...
5
votes
1answer
90 views

Why does aluminium-on-glass mirror work without distortion?

I have read an article about glass (zerodur) with low thermal expansion coefficient. It is mentioned that large casts of such glass are covered with reflective layer of Aluminium and used as mirrors ...
4
votes
4answers
10k views

Why is the conductor an equipotential surface in electrostatics?

Since the electric field inside a conductor is zero that means the potential is constant inside a conductor, which means the "inside" of a conductor is an equal potential region. Why do books also ...
0
votes
0answers
25 views

What is the work-function of a monolayer metal on a substrate with charge redistribution at the interface?

The work-function on subsrate/metal with nm thick (or above) metal layer generally reveal the intrinsic work-funtion of bulk metal. But what if there is a monolayer thick metal, and there is charge ...
0
votes
1answer
62 views

If we hit an electron will it go to an excited state?

For example i have a block of silicon doped with phosphorous and i hit it hard with a hammer will the energy get transfered to the block and make the electrons excited?
2
votes
2answers
14k 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?
1
vote
1answer
90 views

Why does Ohm's law ignore the Lorentz force?

For example, the usual derivation of the complex dielectric constant of metals (using the Drude model) makes use of the Ohm's law in the Maxwell's equations, but what is never mentioned is why they ...
1
vote
1answer
172 views

Grain boundary sliding in creep

To prevent grain boundary sliding so that creep is less likely to occur, usually engineers would design components of larger grains or have columnar grain structure to prevent grain-boundary sliding. ...
1
vote
1answer
40 views

Why metals fused in vacuum? [duplicate]

On Earth when two pieces of metal comes into direct contact with each other, nothing amazing happens. In a complete vacuum condition the two metals fused permanently, how and why?
0
votes
1answer
38 views

How does the Hutchinson Effect work? [closed]

I have seen pictures online of metal ripped apart and metal completely messed up due to the Hutchinson Effect. How does this effect work and what are the other principles behind it?
2
votes
2answers
3k views

Properties to select suitable materials for making permanent magnets

I have read that soft iron is suitable for making a permanent magnet. Because it is required for permanent magnet to have high coercivity and high retentivity. Same text also said earlier that soft ...
0
votes
0answers
16 views

relation between chemically activity and work function and fermi level

I am trying to connect the following concepts together : "being chemically active", "work function" and "fermi level" I want to know if for a metal, "being chemically active" is equivalent to "its ...
0
votes
1answer
29 views

currents in an isolated metal exposed to an alternating uniform electric field

For example, let's look at a metal sphere between a capacitor's (infinite) plates. Let's run an AC current through the capacitor, resulting in an oscillating electric field. The charges will move in ...
1
vote
0answers
28 views

Lindhard function for surface plasmon

Is there anybody that knows how to calculate the Lindhard function for the surface plasmon (between the surface of two metals of different dielectrics)? What I'm looking for is to find this function ...
5
votes
2answers
15k views

Why does magnet attract iron but not other metals?

While searching, i found this page: http://timesofindia.indiatimes.com/home/stoi/Why-does-a-magnet-attract-iron/articleshow/4298171.cms but it does not have full explanation. So Please tell full ...
14
votes
1answer
3k views

When heat is applied to the top of a stack of pennies, why does the bottom penny melt first?

I just watched this video where a blow torch is used on the top of a stack of pennies. I'd like to know why the bottom penny melted first.
1
vote
1answer
173 views

Semiclassical description of EM waves reflection from metallic surfaces

Imagine an EM wave impinging on a metal. Fresnel's formulas tell us that no wave can propagate through the metal, or that the transmitted field is an evascent wave with some penetration depth ...
8
votes
2answers
611 views

Why does Platinum evaporate if left long enough?

I have been reading into research relating to the redefining the 1 kg weight as the current Platinum-Iridium is becoming smaller. In this article, here, it mentions that the original metal weight ...
2
votes
2answers
97 views

Can work hardening of a metal be avoided?

My left earbud recently broke mid-wire: the bit that I like to fiddle with and bend. I fixed it, but I was wondering whether there are metals that don't work harden, or resistant to it? Is there a ...
5
votes
1answer
1k views

Why does a gold leaf appear blue if made very thin?

Is this to do with excitation of electrons and emission of photons? Or is it more to do with the structure of the gold I.e. Only small wavelengths being able to pass through gaps between atoms? EDIT: ...