Given modern manufacturing techniques, the two halves may well be welded
together ultrasonically.

Be advised that the car MIGHT not work if you do that. My little story
revolves around a late model VW, Alfas may be different.

When I took possession of my 2003 VW GTI 1.8ti, it was missing the
second "switch-blade" key (the VW uses the same type of key as do modern
Alfas. It even is made by the same company) but did have a conventional
-looking key called a "valet key". The dealership made me a new second
"switch-blade" key and gave it to me. I didn't have an opportunity to
use it until almost a year later when my primary key fell out of my
pocket and landed on the floor at a friend's house (it also had my latch
key on the same fob). I was driving my Alfetta GTV-6 that day, so I
didn't notice that my VW key was missing until I got home and tried to
unlock my door. Luckily, I have a spare latch key hidden outside on the
premises, and was able to get in. The next day, I got the spare
"switch-blade" key out of the drawer where I keep it and went out to
start my VW to run some errands. The car would catch with the spare key,
I.E. it fit the ignition lock and would turn it, and the car would
crank. But it would die again as soon as it caught. At first I thought
there was something amiss with the VW, but since I had never tried this
second key before, I was suspicious. I went back in the house and
retrieved the valet key and it started the car and it ran fine. I drove
over to my friends house (who had found my keys on his floor) and
retrieved my main keys.

Monday, I called the VW dealership and talked to the service technician
who duplicates keys for them. He said that the ignition switch doesn't
just rely on the physical key, but rather it uses a small transmitter in
the ignition lock which sends out a signal when the lock is turned to
the "start" position. A small coil of wire in the fob acts as an antenna
and a circuit inside called a transponder rebroadcasts the signal back
to the car's electronics but with a digital code now embedded in it. If
the code in the key and the code in the car's ignition switch don't
match, the car will quit immediately. Apparently this so called "valet
key" also has this circuitry in it. Anyway, I took the "switch-blade"
key back to dealership and they found that they had inadvertently
reversed two numbers in the code.

So, you see, taking the flat blade out of your "switch-blade" key may
not work.