Phase transformations in Si-based alloy powder mixtures induced by microwave heating in a 2.45 GHz single-mode applicator

Microwave radiation was used to heat Si and Fe blend powders as well as Si-based alloy powders in a single-mode microwave applicator. The heating behavior and phase transformation of these powders in a separated electric (E)- and magnetic (H)-field were investigated. The increase of Fe content in the mixture of Si and Fe powder enhanced its microwave absorption capability in both the E- and H-fields. Si90Zr10 and Si95Y5 alloy powders could be heated up more easily in the H-field than E-field. Microwave heating of Si and Fe blend powders induced the formation of FeSi2 and FeSi phases in the E- and H-field under a flowing nitrogen gas. When Si70Fe30 blend powders were heated by microwaves in air, crystalline Fe3O4 phase could be detected. SiY phase was formed by microwave heating of Si95Y5 alloy powder in the H-field.