Limit to the strength, the hardness, and the density of a material?

[Researcher X]

Is there a limit to how strong a material we can create? Does yield strength have an upper bound, and how high is that upper bound above materials created today? What about hardness? Is Diamond the limit?

Could we ever make a machine that could survive the pressures and temperature found in the Earth's core?

I'm also wondering whether it's possible to create a stable material denser than Osmium? Density is distinct from strength, I know, but it's also something I've been wondering.

 

[mgb_phys]

Is there a limit to how strong a material we can create? Does yield strength have an upper bound, and how high is that upper bound above materials created today? What about hardness? Is Diamond the limit?

There is an upper limit which is the strength of the molecular or atomic bond inside the material.
Most real materials fail below this limit due to imperfections, scratches etc. It is possible to make small samples with no flaws that reach the atomic limit. I don't know if diamond is exactly the limit - but it will be something close.

Could we ever make a machine that could survive the pressures and temperature found in the Earth's core?

Not quite, carbon and tungsten melt at around 4500C, the Earth's core is a bit more than that. There is also an issue with the mechanical strength of many materials near their melting point.

I'm also wondering whether it's possible to create a stable material denser than Osmium? Density is distinct from strength, I know, but it's also something I've been wondering.

If any of the very heavy atoms Z>118 turn out to be stable, they will have a higher density. but other than temporarily producing higher densities under very high pressure, or counting collapsed matter in neutron stars or white dwarfs - no Osmium is probably the densest 'real' material.

 

[Researcher X]

Sounds like we're stuck with what we've got then when it comes to those properties.

 

[negitron]

...Osmium is probably the densest 'real' material.

Or tungsten, depending upon who you ask. There is no consensus on this point.

 

[mgb_phys]

Or tungsten, depending upon who you ask. There is no consensus on this point.

Really? I though tungsten was about the same density as gold.

 

[Mapes]

Or tungsten, depending upon who you ask. There is no consensus on this point.

Surely you're thinking of iridium, which has a similar density to osmium? (Tungsten's density is about 10% lower and is similar to gold, as mgb_phys states.)

 

[Borek]

NITS lists osmium as slightly denser (22.57 vs 22.42 g/cm³):

http://physics.nist.gov/cgi-bin/Star/compos.pl?matno=076

http://physics.nist.gov/cgi-bin/Star/compos.pl?matno=077