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OrbitalPete t1_iyvuj3a wrote

As you heat metal it becomes much weaker to resisting volumetric change and shear stresses (the bulk modulus (K) and shear modulus (mu) both reduce). Density (rho) reduces very slightly. You will be reducing the speed of sound (P wave velocity, Vp) substantially.

Vp = SqRt((K×4/3mu)/rho)

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MostCuriousExplorer t1_iyw1b09 wrote

Casual physics reader here.

If we’re assuming the baseline to be room temperature, would that mean that colder temperatures increase the rate at which sound travels?

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OrbitalPete t1_iyw2ogc wrote

It's not straightforward, but in general yes

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MostCuriousExplorer t1_iyw4tpd wrote

This opens up a whole slew of new questions for me.

-would each metal would have different thresholds for the rates at which speed could travel through it? (Assuming no sound is held at boiling point due to a change in state)

-would it have different rates of travel as a liquid than a solid, or would we expect a similar waveform?

-is Freezing point the upward maximum for cold? (Because there’s still technically space between atoms at freezing point) if not, how would the rate of travel be predicted to react to drops in temperature past the freezing point (until there’s minimum/no space between atoms)?

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OrbitalPete t1_iyw606j wrote

Sound can travel through any medium except vacuum. Temperature is only enforcing a control because it changes other physical and mechanical properties of a material. Its better to think about those different parameters individually, because the temperature effects are non linear, and vary by material.

Remember- freezing point is simply the point at which a liquid becomes solid (typically we talk about this for water, which occurs at 0 centigrade at standard pressure). We can still transfer pressure waves, the state of matter will change the speed though.

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MostCuriousExplorer t1_iyw6d6k wrote

Do you know if there’s any research/reading material available that shows the differences by metal?

Sorry, don’t wanna bog you down with questions lol.

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OrbitalPete t1_iyw9f9q wrote

I only really deal with it in rocks. The same physics applies to all metals (and other materials!). There's a huge amount of metallurgy research though - look for stuff on young's modulus, bulk modulus and shear modulus. P wave velocities (sound wave, acoustic wave, compression wave - all mean the same thing) aren't used as much in metal analysis, but they are used. You can use the moduli and density data to work out how P wave will respond though.

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