It also says:
Compact Composites: military and authority vessels. That's a tough order, unfortunately. You'll have to find a USS which has a shredded low level mil/auth vessel. I'd have expected in this case that you might have more luck in a combat zone, but harvesting materials in a CZ is a bit hairy.
Filament Composites: Same, but slightly higher ship level
Question is, though, what do you want them for? Those are not used in any Engineer blueprint currently stored on Inara.
Thermic Alloys: shredded combat ships or mission rewards. You may have to do some shredding yourself.
Proto Radiolic Alloys: High Grade USS in boom systems. To find a High Grade USS, get off the beaten path (i.e. your scanner on the left side should state "Deep Space", throttle back and wait. Another thread is currently hotly debating whether you should be 1000 ls from the star or 100,000 ls
As for blowing ships up: they have to be the right type and grade. I'd expect to get Compact Composites occasionally (problem is, they're RNG, and there are many, many Very Common materials) from System Security Sideys and Eagles.
The Thermic Alloys are Rare Combat ship salvage - Federal coffins, FdL and above should occasionally drop them.
Good Luck
