Causes of Premature Alternator Failure

I bought my car brand-new a few years ago, with only 50 miles on it when it came off the lot. It's perfectly stock - no modifications made, though some parts have been replaced for repair purposes.

Because I have a long commute, I blew past the mileage cap for the manufacturer's bumper-to-bumper warranty long before I hit the time limit. Even so, I'm now just a bit outside of what would have been the time limit on that warranty coverage anyway.

Now, with just over 74,000 miles on the car, I'm being told my alternator is making noise and may fail soon. It hasn't been giving me problems in terms of power delivery yet, but the diagnosis does explain some other minor symptoms I've noticed. This was discovered while I had it in the shop for some unrelated issues.

The real kicker though, is that this is already my second alternator. The first failed somewhere around 40,000 miles (outside of warranty due to mileage alone, at the time). That time, it did reach the point of having substantially reduced performance before I realized there was a problem and replaced it.

So now, on a car bought brand-new, I've had two alternators either fail or show indications of imminent failure within around 40,000 miles or less.

All of the vehicles I've owned before this one were bought with at least 90,000 miles on the odometer. For each of those cars, I put at least 100,000 of my own miles on them and only (if ever) had to replace their alternators once.

The first alternator on my current car obviously came straight from the manufacturer. (Again, car was bought brand-new.) The second may have been re-manfactured (I don't recall off the top of my head - will be contacting the shop that did the work when they're open again). Regardless, it seems unusual to me that both should fail so early and both around the same time.

What could be causing this?

Vehicle details:

2012 Dodge Avenger SXT
2.4 L GEMA I4 DOHC 16V Dual VVT 6-speed automatic, FWD