I'm experimenting with induction heating, and made a simple ~100W device. Royer oscillator type, 200kHz frequency. It readily heats a steel blade to the point of incandescence. However, a piece of aluminium of a similar size doesn't even get warm. I understand that magnetic hysteresis helps a lot in iron and other magnetic materials, but i thought eddy currents do their job too, so zero result on aluminium seems just wrong. Is that normal? I've seen videos of 2kW units melting aluminium, how is that possible if at 20 times less it's not even heating up? Also, With big steel piece the coil is hot and MOSFETs are getting hot. With small steel piece the coil stays warm, but transistors still heat up. But, with aluminium the coil is getting hot rather quickly, and the transistors stay completely cold. When empty, it behaves like with aluminium. Oscillations are going in all cases. How does that happen (coil hot, transistors cold)?