Is the qr1 made of plastic

That depends. Your question was not 100% clear since there are multiple QR1 products.
Let me explain:

• The (normal/standard) QR1 Wheel-Side is made from metal

• The QR1 Lite Wheel-Side is made from carbon fibre-reinforced plastic

• The QR1 Base-Side variants are (and have always been) made from metal. This goes back from the original ClubSport Wheel (V1) to the GT DD and CSL DD Wheel Base Series.