Smashed Micro-Cubes for Bulletproof Vests & Vehicle Collision Protection

Rice University scientists have found that firing a tiny, nearly perfect cube of silver onto a hard target turns its single-crystal microstructure into a gradient-nano-grained (GNG) structure. The purpose of the experiment was to learn how materials deform under overwhelming stress, as might be experienced by a bulletproof vest or a spacecraft or other vehicle. The researchers believe creating a gradient nanostructure in materials by way of deformation will make them more ductile and therefore less likely to fail catastrophically when subsequently stressed. Ultimately, they want to develop nano-grained metals that are tougher and stronger than anything available today. The team used its advanced laser-induced projectile impact test (LIPIT) rig to shoot microcubes onto a silicon target. The mechanism allowed them to be sure the cube hit the target squarely.

Transcript

00:00:03 the experiment that we've been doing is to explore how taking this a cube this represents a cube of silver the actual cube is a micron not much much small in this micron is 150th the diameter of a human hair and we use a hard surface of silicon and we impact this cube onto the surface at different orientations the face orientation and edge orientation or corner orientation and then we study the

00:00:32 subsequent deformation of the cube and because we have this apparatus that has a laser to launch the micron size particles up to a kilometer per second so faster than bullets we can actually control and selectively choose which cubes you want to shoot and what velocities want to shoot to achieve that we're here now on a focused ion beam scanning electron microscope a nice

00:00:56 facility here that we have a trice that allows us to look at these cubes that are really quite small and see the details of the deformation this is a cube that was impacted in a 110 direction along an edge and you can see that this conference to some certain symmetry directions in the external side and also you can see the slip systems that are characteristic of the intrinsic

00:01:17 crystal structure so the crystal structure inside is a face centered cubic structure so that leads to this kind of slip system forming over there showing this very interesting deformation so this suggests some extreme events must have happened inside so you take a very thin cross-section about 100 nanometer and look at in the transmission electron microscope

00:01:38 basically what we see here is that solar atoms are rearranged and changes in order to accommodate such a huge deformation and by forming some dislocations many applications different kinds of defects that we can see it here also we can see it is here and the reason we're doing this is because we're trying to attempt to make a gradient nanostructure because we

00:02:03 believe that will improve mechanical properties and in mechanical properties of things most people care about our strength and toughness strength is you know the ability for the material with stance traffic stress and not to form toughness is the ability the material to absorb a lot of energy so it doesn't fracture right away and therefore you get a lot of protection like in a car

00:02:25 crash or bulletproof armor normally when you increase the strength the toughness goes down or when you increase the toughness the strength goes down and our approach here to make these gradient nanostructured materials is to be able to both increase the strength and simultaneously increase the toughness to make materials which are unprecedented in their mechanical properties