The study of how the properties of matter arise from its structure at all scales and of how processing can be used to modify those properties (often in pursuit of a specific application).

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173
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11answers
36k views

Why don't metals bond when touched together?

It is my understanding that metals are a crystal lattice of ions, held together by delocalized electrons, which move freely through the lattice (and conduct electricity, heat, etc.). If two pieces ...
0
votes
0answers
4 views

How to calculate a Mooney-Rivlin material

Well, I'm working on a fsi (fluid-solid/structure interaction) model. I've got ready the fluid part, now I need to get ready the solid part. Since I'm working with tissues, I need to use an ...
1
vote
2answers
42 views

Does induced current affect the permeability of a material?

For electromagnetic wave propagation, we can typically characterize a medium by conductivity $\sigma$, permeability $\mu$, and permittivity $\epsilon$. Consider if this material had current passing ...
5
votes
0answers
71 views

Tensorial version of Hooke's law

It is well known that $${\boldsymbol F} = k {\boldsymbol x}$$ for isotropic media. Also, according to Wikipedia $$F_k = k_{jk} x_j$$ for some elastic tensor $k_{jk}$. I'm a bit confused as to how ...
29
votes
2answers
4k views

Is ice a type of glass?

It's kind of a tricky concept I assume, on one side you got those neat shared vertices of SiO2, on the other (water) you don't really have shared vertices, only kinda (but they still want to align ...
0
votes
1answer
46 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. ...
0
votes
1answer
24 views

Why do we have Indirect bandgap semiconductor?

If the energy of an electron is proportional to square of the momentum k, how come we have a Indirect Bandgap material in which the minimum of the energy in conduction band is not at k not zero. P.S. ...
1
vote
0answers
12 views

Does there exists a flexible supermaterial with which you can write a “thermal image” instead of a visible light image [closed]

I'm thinking a mesh of copper that some how heats up at the touching points and you address each point with rapid switching. Would that not work? Also, what do you suggest as a heater at each of ...
95
votes
3answers
7k views

How does a knife cut things at the atomic level?

As the title says. It is common sense that sharp things cut, but how do they work at the atomical level?
1
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3answers
1k views

Liquid crystal shutter with >90% transmission?

Today's liquid crystal shutter glasses, when in the "transparent" state, exhibit only 40% light transmission. They work using two polarizer layers, one which is liquid crystal and goes {vertical ...
0
votes
1answer
17 views

How can I get some conductive polymer (silicone like), with 1 Ohm/cm resistance? [closed]

I'm looking for a silicone-like (flexible, stretchable) conductive polymer with 1 ohm/cm resistance. Does anyone happen to know where/how can I acquire some? Thank you very much for your time.
3
votes
1answer
285 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
0
votes
1answer
30 views

Why do pores make ceramic opaque?

I want to know how a ceramic transparency is mostly affected by the pores, grain boundary, second phases etc. present inside of it, but the major contribution is due to the pores. Let's consider the ...
0
votes
1answer
623 views

Stress due to the mismatch of thermal expansion coefficients of two different attached materials

I'm simulating the thermo-electro-mechanical behavior of a copper wire which is surrounded by silicon dioxide. In other words, the wire segments is under mechanical and thermal loads and at the same ...
0
votes
1answer
96 views

Melting and Boiling Points of Odd Materials

In Chemistry, I was taught that there are three main states of matter: solid, liquid, and gas, and that heat and pressure determine that state. For some substances, the line is blurry between them. ...
5
votes
1answer
136 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
1
vote
1answer
52 views

What factors cause the velocity saturation to occur at different electric fields for different materials?

In semiconductors the velocity of carriers gets saturated after a certain value of electric field. In silicon it occurs at around $10^4 kV/cm$ and in GaAs at some other value. What factors are ...
2
votes
1answer
78 views

Is it possible that a battery goes flat faster in a cold environment?

I own an old iPod Classic with original lithium-ion polymer battery and I use it primarily while running. Recently I discovered that when a temperature outside is low, usually below 5 C degrees, the ...
0
votes
1answer
45 views

Martian space elevator from the vulcano Olympus Mon to the moon Phobos?

In my fascinating imagination, I am seeing a space elevator from the vulcano Olympus Mon to the moon Phobos. Phobos also seems to keep spaceships - while a smaller shuttle attaches itself to the ...
3
votes
3answers
2k views

Space Elevator on Mars with Today's Technology Possible?

I know it's not possible with Earth today, but With today's level of material science technology, would it be possible to make cable strong and light enough to make a space elevator system connecting ...
1
vote
1answer
18 views

Software for analysing SEM or TEM images

I am looking for a software to analyse SEM and TEM images of some PLD experiments because I want to characterize the samples, like calculate the concentration of nanoparticles, size, and do some ...
3
votes
7answers
176 views

Is it possible to cut harder material with a less hard material?

Is it possible to cut harder material with a less hard material - for example cut a steel rod with iron blade ?
5
votes
2answers
479 views

What properties would the ideal material for spacecraft construction possess?

Assuming we develop the capability to send a robot to study Gliese 518, or any of the Earth-like planets discovered in the neighbourhood; the spacecraft would need to travel through the Solar System ...
1
vote
1answer
42 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 ...
5
votes
3answers
143 views

Are there materials that get softer with temperature decrease?

Could be there material that begins melting/softening when it's temperature is lowered? I would say no, but I've seen enough physics to know that not always life is so easy. Moreover I think I've ...
3
votes
1answer
54 views

How can one reasonably theoretically model polycrystalline materials?

Many techniques are taught in advanced solid state courses but they are almost all derived for perfectly crystalline materials. For example, band structure really only appears theoretically when you ...
12
votes
2answers
627 views

How is graphene a 2D substance?

How is graphene a 2D substance? It has length, width and some thickness to it, else it would be invisible. Why is it considered a 2D substance?
1
vote
0answers
13 views

What are the factors affecting transparency and color of a substance [duplicate]

What is the reason behind visual properties like color and transparency of different substances? I have always heard that the structure of the substance is responsible for these properties. I always ...
0
votes
2answers
54 views

What temperature will create amorphous TiSi?

At what temperature will create amorphous TiSi? I think it's around 500 Celsius but I'm not sure.
0
votes
1answer
17 views

Material for moisture moderation

Do you know of any material that can moderate the level of moisture of its local environment? Example: if the desired moisture level is 30% and the local environment of the material is at 6% the ...
0
votes
0answers
10 views

Material that can provide soft flexibility, while maintaining conduction “accuracy”

I hope material search may be valid here. Is there a material that can be shaped as a few millimeters thick sheet, that can be placed on top a touch surface (e.g. iOS/Android tablet, Wacom drawing ...
2
votes
2answers
66 views

Why is steel-reinforced concrete stronger than ordinary concrete?

Is it only because steel has higher elasticity? What other factors are involved?
2
votes
2answers
911 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 ...
1
vote
0answers
23 views

What is the yield strength of a bar of different cross sections?

Will the yield strength of the combination will be same as that of the rod of uniform cross section?
0
votes
0answers
12 views

What are some structures which minimize surface stress upon expansion

Intro I am currently researching into a problem involving the cyclical expansion and contraction of a 3 layered structure comprised of an internal metal encased by another metal encased in an outer ...
18
votes
1answer
182 views

How many molecules rub off when I press a key?

I have a lot of questions below but my overarching questions are: Do surfaces rubbing lightly together always strip molecules off of each other? and How can we model that? Clearly the answer to the ...
2
votes
1answer
44 views

Demagnetisation by throwing a magnet

I tried to answer this question in a book about electrodynamics: How to demagnetise a permanent magnet, ie. described by $ D_T$ change into described by (0,0) I figured out about heating it up ...
15
votes
4answers
2k views

Is one way glass possible?

I am not talking about mirrors, just a plain window made of glass like material. Would it be possible to allow light pass only in one direction but not the other?
4
votes
2answers
211 views

If atoms have specific energy levels, why do opaque solids absorb all visible light, not just some? [duplicate]

Here's my question: if atoms have well defined energy levels and those differences correspond to the frequencies of light that can be absorbed, how is it that opaque objects absorb all or most visible ...
0
votes
0answers
11 views

Pearlite or spheroidite?

If steel alloy having either pearlitic or bainitic microstructures is heated to, and left at, a temperature below the eutectoid for a sufficiently long period of time (e.g.24hr), spheroidite will ...
1
vote
0answers
43 views

How hard is ice? [closed]

I know that there are many different types of ice and many ways for ice to form but I want to know about ice that a human might typically encounter, i.e. from a freezer or a sub-zero environment ...
1
vote
1answer
126 views

Question about supercooling

During the cooling of a liquid, if no impurity of site of nuclearation, an appreciable solidification will begin only after the temperature has been lowered to below the equilibrium solidification (or ...
0
votes
0answers
40 views

How can a paper battery behave like a capacitor?

I was trying to understand how paper batteries work and came across some explanations saying that the paper battery can also behave like a supercapacitor on account of its ability to discharge and to ...
3
votes
4answers
125 views

Surface area of glass (or general material) and strength

How does the surface area of a piece of glass (or any general material; sapphire isn't technically glass) correlate with strength? Strength as in resistance to pressure concentrated at a small point? ...
0
votes
0answers
15 views

Color of cementite

I have a question about micrograph of steel. In eutectoid steel, the pearlite exists as grains, within each colony the layers are oriented in essentially the same direction, which varies from one ...
1
vote
1answer
76 views

Why can't a dislocation terminate in the bulk?

We are told that they can only terminate on surfaces, grain boundaries or other dislocations but we are not told why they can't terminate inside the crystal.
3
votes
0answers
74 views

A physicists perspective on a material science/engineering problem

I am looking into some research that involves engineering and material science. As a physicists I wondered what other physicists would think of this problem and how they would approach it. Much of the ...
0
votes
1answer
20 views

intermetallics and solid solution

For some systems, discrete intermediate compounds rather than solid solutions may be found on the phase diagram, and these compounds have distinct chemical formulas; for metal–metal systems, they are ...
1
vote
0answers
47 views

Graphene conductor? [closed]

I was thinking if we had a a busbar that can carry massive amounts of current(since its resistance is $0.9\, \mathrm{\mu \Omega}$), and it's weight is $15\, \mathrm{kg}$, I assume if graphene would be ...
13
votes
3answers
251 views

Does extreme cold make **everything** extremely brittle?

First of all, I'm genuinely sorry if this question isn't "serious" enough for this forum! A common cliche in movies and tv is that a very tough object (eg the villain) is frozen, and then hit with ...