Some plates are not microwave safe as they can heat up and could melt, crack, burn your hands or the plates may also have some metal inside them as decoration which could spark.
Aluminum foil can safely go in a regular oven.
However you should not use aluminum foil in a microwave oven as it could spark, create a fire or damage your microwave.
It's best to avoid use of any metal trays or foil in a microwave although foil plates and aluminum foil pans are considered safe to microwave when used properly.
However with a regular oven the aluminum or aluminum foil is not a problem.
A foil plate is considered safe to use in a microwave as long as the foil plate does not touch the sides of the microwave.
It's also recommended to cover the foil plate with some plastic to help deflect the microwaves away from the foil.
The foil plate or even foil tray when used properly in the microwave should not spark but if it does you should turn the microwave off immediately to avoid any damage.
It is actually safe to microwave aluminum trays in the microwave assuming that the tray does not touch the side of the microwave, you use only one tray at a time and that your food is not completely covered by aluminum.
Aluminum trays can be used in the traditional oven and in the microwave.
A study by the Fraunhofer Institute (IVV) in Freising, Germany established that aluminum foil packaging can be safely used in microwave ovens.
The FDA reiterates that food completely covered in aluminum foil should not be put in the microwave here .
The electric fields in microwaves cause charges to flow through metal.
Thin pieces of metal like aluminum foil are overwhelmed by these currents, causing them to heat up so quickly that they can ignite.