Through adding solid FeS2 in a sealed melting furnace for magnesium alloy

effects of FeS2 addition

melting temperature and holding time on protective role of AZ91D magnesium alloy melt were analyzed at air containing FeS2 atmosphere

and morphology

constituent and phase composition of oxidized film were observed by SEM （scanning electron microscope）

EDS（energy dispersive spectrometer） and XRD （X-ray diffraction）. The results show that the acceptable protective effects can be obtained with melting temperature below 760 ℃. Melted at 730 ℃ for 30min

the protective effect is dissatisfied with 1g FeS2 addition

while it is satisfied with 2 g FeS2 and 5g FeS2 addition

however

it is turned bad with FeS2 addition increased to 10 g in the sealed melting furnace with 13 L in volume. Melted at 730 ℃ for 60min

the protective effect is bad with 2g FeS2 addition while it is desirable with 5g FeS2 addition. With melting temperature increased to 800 ℃ for 30 min

the protective effect on AZ91D magnesium alloy is worse that with 2 g FeS2 addiiton. The surface film formed on the magnesium alloy at air containing FeS2 is composed of MgS and MgO phase with compact structure. And the thickness of the film formed is increased with increasing in holding time in range of 1.0

2

.0 μm.