LMAO imagine using experience playing tank video games to make arguments about hypervelocity physics. (this was made by the aerospace engineering gang)
I clearly stated that only a small fraction of the energy would need to be converted to heat to vaporize the object and I wasn't suggesting that anything like a 100% energy conversion would actually occur.
... even if a small fraction of the total energy were converted to thermal energy, aluminum would vaporize...
If as you stated, the velocity changed from 20 km/s to 19 km/s and
only 1% of the lost energy was converted into heat, aluminum would still reach 1.55 million degrees C (again using a bunch of bad assumptions, but the even if the order of magnitude is off by 2, it still proves the point). There's so much energy involved that if any noticeable amount is converted into heat, the object would vaporize.
Tank shells are fired at a small fraction of orbital velocities, and kinetic energy grows with velocity squared so the difference between a 1500 m/s armor penetrating round (
https://en.wikipedia.org/wiki/Armour-piercing_fin-stabilized_discarding_sabot) and 20000 m/s is a factor of 177 (i.e. 177 times as much energy). Tank shells are designed to work at specific velocities and with the material properties associated with impacts at those velocities. Arguing those principles extend to much higher velocities is ridiculous. Any chemically reactive material would undergo reaction on impact (i.e. explosives detonate on impact), and then the result would be a bunch of plasma (explosion + impact would definitely release enough energy for that) that could be redirected with magnetic fields. Would that actually work? Who knows, but trying to use modern military tank shells as evidence for the behavior of a 20 km/s projectile is nonsense. We have very little idea how those sorts of events would actually occur, because they've never happened where we can observe them to take measurements etc. We can't do much beyond computer simulations (based on our assumptions) of that sort of velocity on earth.
For reference, here is video of an impact experiment at 2 km/s
The aluminum sphere and impact area are clearly behaving as a fluid and that's only 2 km/s, slightly faster than the high velocity armor penetrating tank shells cited (you can find that information in the youtube description)
Also here is a paper studying some hypervelocity material properties through computer simulations
https://www.researchgate.net/publication/257657164_The_12_th_Hypervelocity_Impact_Symposium_Large-scale_Molecular_Simulations_of_Hypervelocity_Impact_of_MaterialsThere's some discussion of ionization so magnetic field based deflection approaches seem potentially plausible.
I found some other papers but I can't share them because I only have access through my university