Yes, and aluminium armour actually isn’t that unusual. The M113 (one of the most widely used AFVs in history) also had aluminium armour.
So does the M2/M3 Bradely (supplemented with other armour).
The design spec for the CVRT Scorpion called for it to be able to resist 14.5mm HMG hits to the front from 200m out. It could resist small arms fire and shell splinters all round. At the time, a 14.5mm HMG was the standard armament of Soviet APCs and recce vehicles (BTRs and BRDM-2s)
Yes, aluminium is softer than steel, but you can actually make it just as hard to penetrate as steel by using a thicker slab of it. It turns out that a piece of aluminium armour which offers the same protection as steel weighs less than the steel would. So an aluminium combat vehicle ends up being quite a bit lighter while offering the same protection.
So why aren’t all AFVs aluminium then? Ali is expensive and hard to work with (especially weld), and it burns at a lower temperature. There are a lot of things on the battlefield hot enough to make ali burn, so it’s always been a controversial choice for armour. But does it stop bullets? You bet!
Source: Andy Duffell (Quora)