What happens to a softer material hitting a harder material at high speeds?

I'm going to think that the soft material is so soft that it is something like a gas, I'm also gong to assume that the harder material is fixed in place, so it cannot move after the impact. If the softer material goes fast enough it will definitely cause some damage to the harder one, its kinetic energy must overcome the cohesive energy of the solid at the impact zone.

Note. I'm not 100% sure about this answer, I wish it was a comment instead. Can a mod or someone put it as a comment. Thx.

Soft means that the material is more easily compressed. This would mean that the collision time of impact is greater. Since change in momentum is $Ft$, and $t$ increases, it would mean force decreases. So if you want to use a soft material to smash a wall, two things too take note are, of course the high velocity, and also the high coefficient of restitution. This makes a rubber ball highly ideal.

This is dependent on the elastic property of the material like the maximum stress generated during the collision. If the stress generated is high enough to exceed the materials fracture point (it first have to exceed the yield strength for such to occur). Since stress is dependent on the speed of the particle colliding therefore yes it is possible to do so. But the act of collision not only generates stress in the wall but in the softer body. Therefore you have to keep this fact in mind that the stress in the soft body doesn't exceed it's fracture point but exceeds for the wall.