> Ballistic grade aluminum armor plate...

That's from the same marketing phrase-book as 'aircraft-grade aluminium'.

Lightweight armour ( e.g. personal protection ) uses ceramic plates.

Heavy armour ( e.g. tanks ) still uses steel alloys with composite and plastic layers. There were a few AFVs with aluminium armour, such as the M113 and Sheridan, but ballistic protection was restricted to small-arms and light shrapnel. A Sheridan could be ripped apart by a 12.7mm DhSK.