4 ms·

It is probably very brittle. Diamond is a brittle material and this is basically a 'disordered' diamond. It is quite unlikely that any mechanisms of ductile def

by blix 5y ago

It is probably very brittle. Diamond is a brittle material and this is basically a 'disordered' diamond. It is quite unlikely that any mechanisms of ductile deformation would be active in this material.

sulam 5y ago
Hmm, not a materials scientist here, but wouldn't some of diamond's brittleness derive from its crystalline structure, ie that it's easy for it to sheer along a plane? Whereas this material, being "disordered", to use your term, won't have the same sheer planes and therefore potentially be much less brittle?
- bodhiandphysics 5y ago
  In general disordered materials are more brittle... think glasses, because cracks can propagate in any direction instead of just along crystal faces
- lcvw 5y ago
  In general if a material is shearing along crystal plains the material is breaking apart. Also I am pretty sure that diamonds are polycrystalline meaning that the a diamond is composed of many crystals with different orientations, so it is generally going to break on the boundaries between those crystals not the crystalline bonds themselves. For an example think of a polycrystal like steel (which I’m a little more familiar with), the atoms in the crystal lattice can be displaced a little (elastic deformation) or the crystalline grains can move or change shape (plastic deformation). Once the crystals (grains) themselves shear that means you’ve applied enough stress to break the crystal’s bonds and the material is going to break. Some materials are different though, and sometimes crystals can slip across grain boundaries. But the bonds between the crystals are generally weaker and more prone to move/change, generally polychrystals break along those boundaries first, before the crystals themselves break apart. This is probably very brittle (and hard) not because there are no shear plains, but because there are no mechanisms for the atoms to move around without breaking chemical bonds.
  - scns 5y ago
    Makes sense, turbine blades are nowadays a single "crystal" with no seams. The work on it started in te 60s. First application was in the SR-71 Blackbird, nowadays even blades for generators are made like this.

by blix 5y ago

sulam 5y ago

Hmm, not a materials scientist here, but wouldn't some of diamond's brittleness derive from its crystalline structure, ie that it's easy for it to sheer along a plane? Whereas this material, being "disordered", to use your term, won't have the same sheer planes and therefore potentially be much less brittle?

bodhiandphysics 5y ago
In general disordered materials are more brittle... think glasses, because cracks can propagate in any direction instead of just along crystal faces
lcvw 5y ago
In general if a material is shearing along crystal plains the material is breaking apart. Also I am pretty sure that diamonds are polycrystalline meaning that the a diamond is composed of many crystals with different orientations, so it is generally going to break on the boundaries between those crystals not the crystalline bonds themselves. For an example think of a polycrystal like steel (which I’m a little more familiar with), the atoms in the crystal lattice can be displaced a little (elastic deformation) or the crystalline grains can move or change shape (plastic deformation). Once the crystals (grains) themselves shear that means you’ve applied enough stress to break the crystal’s bonds and the material is going to break. Some materials are different though, and sometimes crystals can slip across grain boundaries. But the bonds between the crystals are generally weaker and more prone to move/change, generally polychrystals break along those boundaries first, before the crystals themselves break apart. This is probably very brittle (and hard) not because there are no shear plains, but because there are no mechanisms for the atoms to move around without breaking chemical bonds.
- scns 5y ago
  Makes sense, turbine blades are nowadays a single "crystal" with no seams. The work on it started in te 60s. First application was in the SR-71 Blackbird, nowadays even blades for generators are made like this.